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Reported waterborne outbreaks of gastrointestinal disease in Australia are predominantly associated with recreational exposure
Abstract
To examine the frequency and circumstances of reported waterborne outbreaks of gastroenteritis in Australia.
Examination of data reported to OzFoodNet between 2001 and 2007.
During these seven years, 6,515 gastroenteritis outbreaks were reported to OzFoodNet, most of which were classified as being transmitted person-to-person or from an unknown source. Fifty-four (0.83%) outbreaks were classified as either 'waterborne' or 'suspected waterborne', of which 78% (42/54) were attributed to recreational water and 19% (10/54) to drinking water. Of the drinking water outbreaks, implicated pathogens were found on all but one occasion and included Salmonella sp. (five outbreaks), Campylobacter jejuni (three outbreaks) and Giardia (one outbreak).
There have been few waterborne outbreaks detected in Australia, and most of those reported have been associated with recreational exposure. However, there are difficulties in identifying and categorising gastroenteritis outbreaks, as well as in obtaining microbiological and epidemiological evidence, which can result in misclassification or underestimation of water-associated events.
Gastroenteritis surveillance data show that, among reported water-associated gastroenteritis outbreaks in Australia, recreational exposure is currently more common than a drinking water source. However, ongoing surveillance for waterborne outbreaks is important, especially as drought conditions may necessitate replacement of conventional drinking water supplies with alternative water sources, which could incur potential for new health risks.
... In Australia, 54 of 6,515 (0.83%) gastroenteritis disease outbreaks were classified as either 'waterborne' or 'suspected waterborne ' between 2001 and 2007, of which 10 (19%) were associated with drinking water (Dale et al. 2010). The implicated pathogens were found on all but one occasion and included Salmonella sp. ...
... The implicated pathogens were found on all but one occasion and included Salmonella sp. (five outbreaks), Campylobacter jejuni (three outbreaks) and Giardia (one outbreak) (Dale et al. 2010). These outbreaks were mainly due to contaminated tank and bore water, not reticulated public water supplies. ...
... These outbreaks were mainly due to contaminated tank and bore water, not reticulated public water supplies. This likely represents an underestimation of water-associated events due to difficulties in identifying, categorising and obtaining microbiological and epidemiological evidence of gastroenteritis outbreaks (Dale et al. 2010). ...
The objective of this study was to evaluate the effectiveness of drinking water quality verification monitoring as a means of improving preventive measures on drinking water quality management in regional New South Wales (NSW), Australia. Water sampling and E. coli detection data were obtained from the NSW Drinking Water Database. Statistical analysis was performed using Incidence Rate Ratios to compare the relationship between the proportion of samples collected to the tests allocated based on population served (sampling adequacy), E. coli detection and the relationship between sampling adequacy and E. coli detections over time. Sampling adequacy and E. coli detections significantly improved during the study period. Sampling adequacy was significantly lower in smaller populations (IRR = 0.83, p = 0.036). E. coli detections were significantly increased in smaller communities (IRR = 4.3, p = 0.01) and in summer (IRR = 2.7, p = < 0.001). There was a strong inverse correlation between improved sampling adequacy and decreased E. coli detections (Spearman’s rho = −0.821; p < 0.0001). This research has highlighted the value of continued assistance to water utilities in the implementation of drinking water management systems to improve drinking water safety.
... There are difficulties in identifying and categorising gastroenteritis outbreaks, and in obtaining microbiological and epidemiological evidence, which can result in misclassification or underestimation of water-associated events (Dale et al. 2010). Multiple factors contribute to the ability of health authorities to recognise, investigate, and report waterborne-disease outbreaks. ...
... Cretikos, Telfer, and McAnulty (2008) noted that the higher rates of disease outbreaks in NSW were reported by the Public Health Units (PHU) with resources dedicated to enteric disease surveillance and control. Thus it is difficult to precisely quantify the contributions of drinking water related disease in relation to food related or water hygiene related disease (Fewtrell et al. 2007;Dale et al. 2010). Reports of sporadic illnesses and outbreaks due to water of unknown intent or not intended for drinking in camping sites have been reported in the USA (Craun et al. 2010). ...
... Pathogenic microorganisms, including cyanobacteria, bacteria, protozoa and viruses can cause diarrhoeal disease. Despite the limitations of surveillance systems, there are a few documented waterborne gastroenteritis disease outbreaks in Australian recreational parks (Dale et al. 2010). NSW Health has recorded some outbreaks of waterborne gastroenteritis in rural caravan parks, school camps and holiday facilities with a private water supply. ...
Recreational parks in the Hunter New England region of New South Wales, Australia, are very popular. Ensuring drinking water safety in the parks requires the application of a considered risk management approach. The study evaluated the compliance of public recreational parks with the NSW Public Health Act 2010 and NSW Public Health Regulation 2012 requirements to implement Quality Assurance Programs. Between March and August 2016, drinking water supplies in 54 national and three state recreational sites in regional Hunter New England were surveyed to evaluate whether the recommendations from the initial survey of 2010–2011 were implemented. The results were compared to the first survey results. All recreational sites developed and implemented drinking water quality assurance programs, compared to four during the first survey. Fifty two of 57 (91%) sites had warning signs at water outlets compared to 34 (60%) during the first survey. There were statistically significant improvements in the provision of water quality warning signs and implementation of water quality assurance programs (p < 0.0001 McNemar Chi² Test) between the first and second surveys demonstrating a good example of beneficial policy change, with regulatory support. Further research is required to understand the ongoing challenges of drinking water management in recreational parks.
... Among the pathogenic bacteria, virulent Escherichia coli serotypes (e.g., O157:H7), Campylobacter spp., Legionella spp., Shigella spp., Salmonella spp., and Pseudomonas spp. were most commonly identified etiologic agents [28][29][30][31][32]. While other protozoan species are occasionally identified as the cause (e.g., Naegleria spp.), [27,30], Cryptosporidium spp., followed by Giardia spp. ...
... While other protozoan species are occasionally identified as the cause (e.g., Naegleria spp.), [27,30], Cryptosporidium spp., followed by Giardia spp. are etiological agents for the majority of recreational waterborne outbreaks [28,29,31,32]. Regarding viral pathogens, noroviruses and adenoviruses were most frequently identified as causative agents in outbreaks where etiology was confirmed [27,30,32,33]. ...
... In treated waters (e.g., swimming pools and spas), Cryptosporidium spp. are most often identified as etiological agents [30][31][32], although noroviruses and adenoviruses are becoming more frequently detected [33]. It is important to note that etiological agents in nearly 30% of outbreaks in the US alone remain unidentified [27], and that sporadic recreational waterborne illnesses not associated with outbreaks are excluded from this report. ...
Fecal pollution of recreational waters can cause scenic blight and pose a threat to public health, resulting in beach advisories and closures. Fecal indicator bacteria (total and fecal coliforms, Escherichia coli, and enterococci), and alternative indicators of fecal pollution (Clostridium perfringens and bacteriophages) are routinely used in the assessment of sanitary quality of recreational waters. However, fecal indicator bacteria (FIB), and alternative indicators are found in the gastrointestinal tract of humans, and many other animals and therefore are considered general indicators of fecal pollution. As such, there is room for improvement in terms of their use for informing risk assessment and remediation strategies. Microbial source tracking (MST) genetic markers are closely associated with animal hosts and are used to identify fecal pollution sources. In this review, we examine 73 papers generated over 40 years that reported the relationship between at least one indicator and one pathogen group or species. Nearly half of the reports did not include statistical analysis, while the remainder were almost equally split between those that observed statistically significant relationships and those that did not. Statistical significance was reported less frequently in marine and brackish waters compared to freshwater, and the number of statistically significant relationships was considerably higher in freshwater (p < 0.0001). Overall, significant relationships were more commonly reported between FIB and pathogenic bacteria or protozoa, compared to pathogenic viruses (p: 0.0022–0.0005), and this was more pronounced in freshwater compared to marine. Statistically significant relationships were typically noted following wet weather events and at sites known to be impacted by recent fecal pollution. Among the studies that reported frequency of detection, FIB were detected most consistently, followed by alternative indicators. MST markers and the three pathogen groups were detected least frequently. This trend was mirrored by reported concentrations for each group of organisms (FIB > alternative indicators > MST markers > pathogens). Thus, while FIB, alternative indicators, and MST markers continue to be suitable indicators of fecal pollution, their relationship with waterborne pathogens, particularly viruses, is tenuous at best and influenced by many different factors such as frequency of detection, variable shedding rates, differential fate and transport characteristics, as well as a broad range of site-specific factors such as the potential for the presence of a complex mixture of multiple sources of fecal contamination and pathogens.
... Cryptosporidiosis outbreaks in Australia have predominantly been attributed to contaminated recreational waters [1,[11][12][13][14][15][16][17][18] with one report of an outbreak due to contaminated milk [19], another outbreak linked to contact with animals at a nursery [20] and several others, for which the cause was unknown [21,22]. ...
... A previous investigation into the 2007 outbreak revealed that it was likely associated with swimming pools, with subsequent secondary person-to-person transmission [15,16]. The 2007 outbreak was also the most prolonged outbreak of the three, beginning in late spring (November 2006) and ending in late winter (August 2007). ...
... The 2007 outbreak was also the most prolonged outbreak of the three, beginning in late spring (November 2006) and ending in late winter (August 2007). Previous studies have shown that waterborne cryptosporidiosis outbreaks were more likely to occur during this period, as a result of an increase in recreational water activities [15,29]. The three outbreaks presented in the present study occurred during late spring/early summer periods, when there would have been an increase in recreational water activities such as swimming in swimming pools, water catchments and natural water holes. ...
Cryptosporidium is a protozoan parasite that causes the diarrhoeal disease, cryptosporidiosis. Although many species have been identified, the majority of human disease worldwide is caused by two species; Cryptosporidium parvum and Cryptosporidium hominis. In Australia, data from the National Notifiable Diseases Surveillance System (NNDSS) show that cryptosporidiosis outbreaks occur every few years. To better understand the transmission, trends and nature of cryptosporidiosis outbreaks in Western Australia, epidemiological and genomic data from three cryptosporidiosis outbreaks in 2003, 2007 and 2011 were reviewed. The 2007 outbreak was the largest ( n = 607) compared with the outbreaks in 2003 ( n = 404) and 2011 ( n = 355). All three outbreaks appeared to have occurred predominantly in the urban metropolitan area (Perth), which reported the highest number of case notifications; increases in case notifications were also observed in rural and remote areas. Children aged 0–4 years and non-Aboriginal people comprised the majority of notifications in all outbreaks. However, in the 2003 and 2007 outbreaks, a higher proportion of cases from Aboriginal people was observed in the remote areas. Molecular data were only available for the 2007 ( n = 126) and 2011 ( n = 42) outbreaks, with C. hominis the main species identified in both outbreaks. Subtyping at the glycoprotein 60 ( gp60 ) locus identified subtype IbA10G2 in 46.3% and 89.5% of C. hominis isolates typed, respectively, in the 2007 and 2011 outbreaks, with the IdA15G1 subtype was identified in 33.3% of C. hominis isolates typed in the 2007 outbreak. The clustering of cases with the IdA15G1 subtype in the remote areas suggests the occurrence of a concurrent outbreak in remote areas during the 2007 outbreak, which primarily affected Aboriginal people. Both the C. hominis IbA10G2 and IdA15G1 subtypes have been implicated in cryptosporidiosis outbreaks worldwide; its occurrence indicates that the mode of transmission in both the 2007 and 2011 outbreaks was anthroponotic. To better understand the epidemiology, sources and transmission of cryptosporidiosis in Australia, genotyping data should routinely be incorporated into national surveillance programmes.
... Cryptosporidium is a parasitic protozoan that is mainly transmitted via the faecal-oral route and is the leading etiological agent in many recreational water-associated outbreaks worldwide [1,2]. Cryptosporidiosis is a notifiable disease in Australia, and data indicate that aquatic facilities are a major source of cryptosporidiosis outbreaks [2][3][4][5][6][7][8]. ...
... Cryptosporidium is a parasitic protozoan that is mainly transmitted via the faecal-oral route and is the leading etiological agent in many recreational water-associated outbreaks worldwide [1,2]. Cryptosporidiosis is a notifiable disease in Australia, and data indicate that aquatic facilities are a major source of cryptosporidiosis outbreaks [2][3][4][5][6][7][8]. This is mainly due to the resistance of the parasite's environmental stage, the oocyst, to normal chlorine levels used to disinfect pools, its very low infectious dose (1-125 oocysts), and small size that render most pool filtration systems ineffective in removing oocysts and preventing outbreaks [9][10][11]. ...
PurposeThere is a dearth of research conducted on the Knowledge, Attitude and Practices (KAP) of swimming pool patrons and staff to determine their understanding of the importance of Cryptosporidium and its transmission in swimming pools.Methods
We conducted a KAP survey of public swimming pool patrons (n = 380) and staff (n = 40) attending five public swimming pools in Western Australia (WA).ResultsKnowledge, attitudes and practices (KAP) of Cryptosporidium varied between patrons and staff but were generally limited. Only 26.1% and 25.0% of patrons and staff had heard of Cryptosporidium, while 17.4% and 10.0% knew that it causes diarrhoea, respectively. Thirty-one percent of patrons were aware of their pool policy concerning gastroenteritis and Cryptosporidium, compared to 62.5% of staff. Less than 50% of patrons demonstrated awareness of how features within the pool environment were relevant to the control of Cryptosporidium. Only about a third of patrons (35%) and staff (37.5%) were aware that showering before swimming reduced the risk of gastroenteritis.Conclusion
Raising awareness about hygiene-related practices through the delivery of targeted health education messages to the general public is essential to reduce the burden of Cryptosporidium infections in aquatic environments.
... Salmonellosis affects 1.2 million Americans annually (Scallan et al. 2011), with tens of millions of cases worldwide each year (WHO 2013). Infections can be caused by consumption of contaminated seafood, meat, eggs, dairy, juice, fresh produce, or water (Dale et al. 2010;FDA 2012). Quality control plans, mandatory testing of eggs, and hazard analysis at critical control points (HACCP) are used to reduce the spread of Salmonella in the Unites States (US). ...
... Despite these efforts, persistence of Salmonella (SALM) in the farm environment continues to be a concern for dairy, livestock and poultry operations, and growers of vegetables and leafy greens (CDC 2010;Jacobsen and Bech 2012;Berghaus et al. 2013). Additionally, the risk of transport of manure-derived bacteria to surface and groundwater resources is a concern worldwide (Unc and Goss 2004;Dale et al. 2010;WHO 2012;USEPA 2013). ...
Minimizing the risks associated with manure-borne pathogenic microorganisms requires an understanding of microbial survival under realistic field conditions. The objective of this 3-year study was to assess the fate of Salmonella (SALM) and fecal indicator bacteria (FIB), E. coli (EC) and enterococci (ENT), in glacial till-derived soils, after application of poultry manure (PM) to cornfields under chisel-plowed (CP) or no-till (NT) management. From 2010 to 2012, soil samples were obtained each spring at 0–15- and 15–30-cm depths, to determine whether over-wintering of target bacteria had occurred. Sampling was followed by application of PM at low (PM1) and high (PM2) rates, based on nitrogen application goals. In 2012, soil samples were collected 21, 42, and 158 days after manure application (DAM), to assess the effects of time, application rates, and tillage on frequency of detection and concentrations of target bacteria. Despite dry conditions, all three target organisms were detected 158 DAM in 2012, and detection of these organisms in spring soil samples from manured plots in 2011 and 2012, nearly a full year after PM application, suggests that these organisms can persist in the soil environment long after application. The highest SALM concentration (790 cfu/g dry weight) and detection rate (25%) was found in PM2 plots 42 DAM. SALM were detected more frequently in CP plots (20%) compared to NT plots (5%). In contrast, tillage practices had no apparent effect on EC or ENT survival, as indicated by both soil, and decay rates estimated from tile-water bacteria concentrations. Decay rate constants (μ) ranged from 0.044 to 0.065 day⁻¹ for EC and 0.010 to 0.054 day⁻¹ for ENT. © 2018, Springer International Publishing AG, part of Springer Nature.
... Water sources New Zealand 14 [42] Swimming pool Victoria, Australia 30 [43] Drinking water New Hampshire, EU 31 [44] Water sources New York, EU 36 [45] Recreational water California, EU 50 [46] Water supply Izmir; Turkey 196 [47] Food/water Scotland 185 [35] Contaminated water Bergen, Norwegian 2500 [48] Foodborne/anthropogenic All states in EU 19,140 [49] (WHO) estimates that at least 10 9 cases of gastrointestinal diseases occur per year in one-third of the countries in the world, causing mortality of more than 5 × 10 6 persons at early age. The economic costs of diseases are alarming and cause financial losses. ...
... Climatic change is actually being considered as a triggering infection risk factor of zoonotic diseases because certain temperature conditions may increase the pathogens' infective capacity. In the case of Giardia cysts, the temperature may be a determining factor in its propagation because an increase in temperature may promote transmission although at low temperatures the cysts viability remains stable [33]; it may be due to increased intake of contaminated water either for drinking or using it for recreational activities [43]. ...
... However, these results indicate potential waterborne transmission of gastrointestinal pathogens in Australia, and occasional waterborne outbreaks have been reported. 10 The cases attributed to waterborne transmission included both drinking water and recreational water exposure meaning the WHO drinking water target cannot be directly applied to our DALY burden estimates for waterborne disease. A recent Canadian study estimated the proportion of waterborne cases attributable to recreational water exposure was 22.0% for campylobacteriosis, 18.7% for cryptosporidiosis, and 32.1% for giardiasis cases. ...
... 11 In contrast, of the 54 "waterborne" or "suspected waterborne" gastroenteritis outbreaks reported to Australia's OzFoodNet from 2001 to 2007 (all attributed to pathogens included in this study), 78% were attributed to recreational water and 19% to drinking water. 10 Significantly, six of the 10 drinking water outbreaks identified occurred at camps and one in a public rural bore water supply; these did not involve public reticulated water supplies. The large urban water supplies providing water to a high proportion of Australians recorded no outbreaks from 2000 to 2007. ...
Universal access to safe drinking water is a global priority. To estimate the annual disease burden of campylobacteriosis, nontyphoidal salmonellosis, cryptosporidiosis, giardiasis, and norovirus attributable to waterborne transmission in Australia, we multiplied regional World Health Organization (WHO) estimates of the proportion of cases attributable to waterborne transmission by estimates of all-source disease burden for each study pathogen. Norovirus was attributed as causing the most waterborne disease cases (479,632; 95% uncertainty interval [UI]: 0-1,111,874) followed by giardiasis and campylobacteriosis. The estimated waterborne disability-adjusted life year (DALY) burden for campylobacteriosis (2,004; 95% UI: 0-5,831) was 7-fold greater than other study pathogens and exceeded the WHO guidelines for drinking water quality (1 × 10-6 DALY per person per year) by 90-fold. However, these estimates include disease transmitted via either drinking or recreational water exposure. More precise country-specific and drinking water-specific attribution estimates would better define the health burden from drinking water and inform changes to treatment requirements. Copyright © 2017 by The American Society of Tropical Medicine and Hygiene.
... 14 In Australia, reports of waterborne gastroenteritis outbreaks are rare. 15 Most Australians are supplied with potable water by retail water corporations. This water is often disinfected, which, together with filtration, is credited with substantial reductions in waterborne disease. ...
Introduction:
Pathogens can enter the drinking water supply and cause gastroenteritis outbreaks. Such events can affect many people in a short time, making them a high risk for public health. In Australia, the Victoria State Government Department of Health is deploying a syndromic surveillance system for drinking water contamination events. We assessed the utility of segmented regression models for detecting such events and determined the number of excess presentations needed for such methods to signal a detection.
Methods:
The study involved an interrupted time series study of a past lapse in water treatment. The baseline period comprised the four weeks before the minimum incubation period of suspected pathogens, set at two days post-event. The surveillance period comprised the week after. We used segmented linear regression to compare the count of gastroenteritis presentations to public hospital emergency departments (EDs) between the surveillance and baseline periods. We then simulated events resulting in varying excess presentations. These were superimposed onto the ED data over fifty different dates across 2020. Using the same regression, we calculated the detection probability at p < 0.05 for each outbreak size.
Results:
In the retrospective analysis, there was strong evidence for an increase in presentations shortly after the event. In the simulations, with no excess presentations (i.e., with the ED data as is) the models signalled 8% probability of detection. The models returned 50% probability of detection with 28 excess presentations and 100% probability of detection with 78 excess presentations.
Conclusions:
The transient increase in presentations after the event may be attributed to microbiological hazards or increased health-seeking behaviour following the issuing of boil water advisories. The simulations demonstrated the ability for segmented regressions to signal a detection, even without a large excess in presentations. The approach also demonstrated high specificity and should be considered for informing Victoria's syndromic surveillance system.
... As is shown in Fig. 3, the upper bound of Salmonella risk for all the target groups exceeded the 0.05 level, suggesting high concentrations of Salmonella in our beaches would lead to estimated risks above the WHO benchmark. There are some reports of salmonellosis outbreaks associated with recreational waters around the world (Craun et al., 2005;Dale et al., 2010), highlighting the importance of monitoring this pathogenic microorganism in recreational waters. Purnell et al. (2020) reported that recreational activities in surface waters impacted by wastewater may pose a negligible risk of Salmonella and Cryptosporidium infections (<0.01). ...
The purpose of this study was to evaluate the microbial characteristics of coastal waters which are impacted by anthropogenic pollution as well as estimate the health risks associated with exposure to enteric and non-enteric microorganisms during swimming. Fecal indicator bacteria were highly detected in samples. Moreover, patho-genic and opportunistic microorganisms were found, with the highest frequency for Pseudomonas aeruginosa followed by Adenovirus 40/41, Acanthamoeba spp., Salmonella enterica, and Cryptosporidium parvum. The median risk of gastrointestinal illness through ingestion of water was estimated to be above the benchmark value of 0.05 per event recommended by WHO. Cryptosporidium followed by Adenovirus, showed higher illness risks than Salmonella. The potential risks of Acanthamoeba and P. aeruginosa were estimated to be low for both dermal and ocular exposure routes. However, there are uncertainties about the infectious fraction of pathogens existing in coastal waters and the delivered dose of microorganisms from dermal/ocular exposure during recreational activities.
... 5 In Australia, a survey reported 6515 cases of gastroenteritis outbreaks between 2001-2007, of which 0.83% were associated with waterborne (or suspected waterborne) diseases. 6 Rapid and reliable identification of contaminated water would dramatically reduce mortality and morbidity due to water-borne diseases. Contamination of environmental waterways with human faecal matter can occur both from direct deposits of sewage or faecal sludge from treatment plants under back pressure during flooding, resulting in sewage runoffs targeted to local waterways through emergency relief structures instead of flowing back to residential systems, and via more diffuse inputs from failing sewage infrastructure and poorly maintained septic systems. ...
Increasing human population growth worldwide continues to put pressure on waterway quality. Timely diagnosis of human faecal contamination of water remains a major challenge in protecting water quality across the globe. Currently, methods of pathogen-detection in environmental waters – including culturing and polymerase chain reaction (PCR) – are relatively time-consuming, expensive, and complicated, often requiring technical expertise in a centralised laboratory. The risks to human health and the high economic impact of human faecal pollution drive the need for rapid and reliable detection methods: a field- deployable method to detect the presence of human faecal matter has the potential to dramatically streamline on-site spill-management processes. To meet this need, we optimised an in-field loop- mediated isothermal amplification assay (LAMP) based on the detection of the human-associated Bacteroides 16s rRNA marker, HF183, to specifically identify human faecal pollution in environmental waters. To purify water samples in the field, a rapid filtration protocol and lysis buffer were combined with our Bacteroides LAMP assay (Bac-LAMP). The Bac-LAMP assay can reliably detect less than 2 CFU μL−1 in a time to positive (TP) of under 10 minutes with no off-target reaction with animal faeces (dog, cat, sheep, cow, quail and horse) commonly found in waterways. A sensitivity and specificity of 100% were seen when compared to the approved United States Environmental Protection Agency (USEPA) TaqMan HF183 qPCR assay. For the first time, this study demonstrates a simplified sampling protocol combined with a LAMP- based assay for the field detection of human faecal contamination in waterways in and around Melbourne, Australia.
... In Australia, cryptosporidiosis is a nationally notifiable disease. Between 2001 and, contamination of swimming pools with Cryptosporidium spp. was linked with almost all (41/42) reported outbreaks of recreational water associated gastroenteritis (Dale et al., 2010). Between 2013 and 2017 in Victoria, Australia, 70 outbreaks of cryptosporidiosis were associated with aquatic facilities, with 421 confirmed cases (Cullinan et al., 2020). ...
Cryptosporidium is an important protozoan parasite and due to its resistance to chlorine is a major cause of swimming pool-associated gastroenteritis outbreaks. The present study combined contact tracing and molecular techniques to analyse cryptosporidiosis cases and outbreaks in Western Australia in 2019 and 2020. In the 2019 outbreak, subtyping at the 60 kDa glycoprotein (gp60) gene identified 89.0% (16/18) of samples were caused by the C. hominis IdA15G1 subtype. Amplicon next generation sequencing (NGS) at the gp60 locus identified five C. hominis IdA15G1 subtype samples that also had C. hominis IdA14 subtype DNA, while multi locus sequence typing (MLST) analysis on a subset (n = 14) of C. hominis samples identified three IdA15G1 samples with a 6 bp insertion at the end of the trinucleotide repeat region of the cp47 gene. In 2020, 88.0% (73/83) of samples typed were caused by the relatively rare C. hominis subtype IbA12G3. Four mixed infections were observed by NGS with three IdA15G1/ IdA14 mixtures and one C. parvum IIaA18G3R1 sample mixed with IIaA16G3R1. No genetic diversity using MLST was detected. Epidemiological and molecular data indicates that the outbreaks in 2019 and 2020 were each potentially from swimming pool point sources and a new C. hominis subtype IbA12G3 is emerging in Australia. The findings of the present study are important for understanding the introduction and transmission of rare Cryptosporidium subtypes to vulnerable populations.
... In general, the chlorine-resistant parasitic protozoan, Cryptosporidium hominis is the leading cause of gastroenteritis in swimming pools, and results from faecal accidents/releases (Suppes et al. 2016) referred to in this paper as bather shedding. Human faeces may contain pathogens and is a known pathway of infection in recreational water environments (Chalmers 2012, Dale et al. 2010, Graciaa et al. 2018, Pond 2005. Hence, in a natural pool, without chemical disinfectant residual, expected bather shedding of pathogens will go untreated until the pool water is passed through sufficient 'natural' barriers, with human enteric viruses the most numerous and infectious of these enteric pathogens (Ashbolt 2015). ...
Natural swimming ponds (NSPs) are artificially created bodies of water intended for human recreation, characterised by the substitution of chemical disinfection with natural biological processes for water purification. NSPs are growing in popularity, however little is known regarding the public health risks. A screening level risk assessment was undertaken as an initial step in assessing the first Canadian public NSP located in Edmonton, Alberta. Risk of enteric pathogens originating from pool bathers was assessed under normal conditions and following accidental faecal release events. The performance of the natural treatment train for health protection was quantified with and without the addition of UV disinfection of naturally-treated water, and compared to the US EPA benchmark to provide a reference point to consider acceptability. Estimated levels of pathogen contamination of the pond were dependant upon the discrete number of shedders present, which in turn depended upon the prevalence of infection in the population. Overall performance of the natural disinfection system was dependant upon the filtration rate of the natural treatment system or turnover time. Addition of UV disinfection reduced the uncertainty around the removal efficacy, and mitigated the impact of larger shedding events, however the impact of UV disinfection on the natural treatment biome is unknown. Further information is needed on the performance of natural barriers for pathogen removal, and therefore challenge studies are recommended. Given the identified risks, the pool is posted that there is risk from accidental faecal releases, as in any natural water body with swimmers. Screening level risk assessment was a valuable first step in understanding the processes driving the system and in identifying important data gaps.
... They are recognized as common etiological agents for water-borne disease outbreaks (Nimgaonkar et al., 2018;Wilhelmi et al., 2003), e.g., infectious diarrhea, Hepatitis A, and Hepatitis E. According to the World Health Organization (WHO), human enteric viruses infect billions of people every year and the resultant diarrheal disease accounts for the second leading cause of death in children under 5 years globally (WHO, 2018). Due to their strong environmental resistance, human enteric viruses have been widely found in recreational marine water around the world (Dale et al., 2010;Dias et al., 2018;Guzman-Herrador et al., 2015;Hlavsa et al., 2015), with an increased number of suspected outbreaks of gastroenteritis related to bathing water (Kauppinen et al., 2017;Sekwadi et al., 2018). Moreover, recreational water is the leading attributable cause of acute gastrointestinal illness (AGI) during the swimming season (Sanborn and Takaro, 2013). ...
Human enteric virus occurrence in bathing beaches poses a potential health risk to swimmers. They may come from several sources, but the understanding of the seasonal contribution of contamination sources to virus occurrence is still lacking. Here, the surveillance of human enteric viruses at the First Bathing Beach in Qingdao was performed January–December 2018. The occurrence of Enteric viruses, assayed with quantitative polymerase chain reaction (qPCR), was analyzed at temporal and spatial levels to determine the viral contamination sources. The results showed that only Astroviruses (AstVs) and Adenoviruses (HAdVs) were found in the swimming area. Their occurrence correlated significantly with the sewage-polluted area, but HAdVs were only found in autumn and AstVs in spring. Meanwhile, enteric viruses in the swimming area showed significantly higher levels than the surrounding area, particularly AstVs in summer with the swimmer crowd. All these data imply that sewage discharge and swimmers co-contribute to the viral occurrence in a seasonal pattern, with the former being more focused in warm seasons (spring and autumn) and the latter in hot seasons (summer). These results indicate that sewage discharge and crowd swimmers, as unsafe swimming conditions, should be avoided to improve public health at the bathing beaches.
... Moreover, chlorination of the water is recommended since there have been several outbreaks of gastrointestinal disease in recreational waters in Australia [56] and the US [55]. The etiological agents in those outbreaks have been Shigella sp., E. coli O157:H7, Leptospira sp., Giardia lamblia, Cryptosporidium parvum, Norwalk-like viruses and Adenovirus 3. ...
Balneotherapy is an ancient practice which remains commonplace throughout the world due to perceived health benefits that include relief of arthritis, fibromyalgia and relaxation. However, bathing environments are not sterile and natural spring waters may harbour natural microbial populations that include potential pathogens. We elucidated the microbial community from water taken from the borehole, pre-filter water (chlorinated, cold and post-bathing water) and post-filter water at a commercial Australian natural hot spring bathing facility. Thiobacillus, Sphingobium and Agrobacterium were the predominant genera in samples collected from the borehole. The predominant genera changed to Sphingobium, Parvibaculum and Achromobacter following chloride treatment and Azospira replaced the Achromobacter once the water reached ambient temperature and was stored ready to be used by bathers. The microbial community changed again following use by bathers, dominated by Pseudomonas, although Sphingobium persisted. No total or faecal coliforms were observed in any of the samples except for the post-bathing water; even there, their presence was at very low concentration (2.3 cfu/mL). These results confirm the lack of pathogens present in these hot spring waters but also suggests that good management of post-bathing water is required especially if the water is used for borehole water recharge.
... Campylobacter spp are frequently detected in surface water (Denis et al., 2011, Guy et al., 2018 as a result of fecal contamination from wastewater effluents, farm animals and wild birds (Pitkänen, 2013. Furthermore, several outbreaks were linked to recreational and drinking water (Dale et al., 2010, Pitkänen, 2013, Moreira & Bondelind, 2017. Among animal contact routes, direct or indirect contact with farm animals and pets are significant risk factors for children and the mixed population. ...
Campylobacter spp. is an important causative agent of diarrheal illness worldwide. The disease is frequently associated with foodborne transmission, but other routes of exposure are increasingly recognized. A systematic review and meta-analysis of case-control studies were performed to determine the main risk factors associated with sporadic campylobacteriosis. Suitable scientific articles published up to March 2017 were identified through a systematic literature search and subject to methodological quality assessment. From each study, odds ratios (OR) as measures of association were extracted or calculated, as well as study characteristics such as study population, design, type of model used and risk factor categorization. Mixed-effects meta-analytical models were adjusted by population type to appropriate data partitions. From 4453 identified references, the quality assessment stage was passed by 71 case-control studies focusing on sporadic campylobacteriosis. The eligible studies were conducted between 1981 and 2012 and provided 1336 ORs for meta-analysis. The meta-analysis identified international travel (pooled OR=4.626), recent use of gastric antacids (pooled OR=2.911), occupational exposure to animals/carcasses (pooled OR=3.022), and food consumption (in particular raw or undercooked eggs, poultry, beef, and dairy) as the main risks factors for sporadic campylobacteriosis in the mixed population. In the child population, the main risk factors concerned environmental/animal transmission routes (e.g. drinking untreated water (pooled OR=3.261), exposure to recreational water (pooled OR=3.156), exposure to farm/rural environment (pooled OR=3.128), contact with farm animals (pooled OR=2.747), person-to-person transmission (pooled OR=2.736) and consumption of raw milk (pooled OR =2.603). The results of this meta-analysis highlight the importance of overlooked routes and vehicles of transmission (environment, animal contact, and other food vehicles) of Campylobacter that should be explored in dedicated studies.
... Thus, V. parahaemolyticus was chosen as one of the most representative species responsible for intestinal symptoms and because of its high detection rate (45%) in the study area . Salmonella has been included in the model because several European monitoring studies have demonstrated its relatively high prevalence in coastal waters (Efstratiou and Tsirtsis, 2009;Mansilha et al., 2010) and outbreaks of Salmonella associated with recreational waters are reported throughout the world (Dale et al., 2010). ...
Profiling bathing waters supported by Quantitative Microbial Risk Assessment (QMRA) is key to the WHO's recommendations for the 2020/2021 revision of the European Bathing Water Directive. We developed an area-specific QMRA model on four pathogens, using fecal indicator concentrations (E. coli, enterococci) for calculating pathogen loads. The predominance of illness was found to be attributable to Human Adenovirus, followed by Salmonella, Vibrio, and Norovirus. Overall, the cumulative illness risk showed a median of around 1 case/10000 exposures. The risk estimates were strongly influenced by the indicators that were used, suggesting the need for a more detailed investigation of the different sources of fecal contamination. Area-specific threshold values for fecal indicators were estimated on a risk-basis by modelling the cumulative risk against E. coli and enterococci concentrations. To improve bathing waters assessment, we suggest considering source apportionment, locally estimating of pathogen/indicator ratios, and calculating site-specific indicators thresholds based on risk assessment.
... contamination of swimming pools was associated with 41 of the 42 reported outbreaks of waterborne gastroenteritis associated with recreational water. 28 Between 2013 and 2017 in Victoria, Australia, 70 outbreaks of cryptosporidiosis were associated with aquatic facilities, with 421 confirmed cases (Joy Gregory, Department of Health and Human Services, May 2018, personal written communication). For the current study, aquatic facilities are inclusive of public recreational swimming pools and splash parks, and hotel and motel pools. ...
Objective : To identify barriers and enablers to preventing and controlling Cryptosporidium spp. in aquatic facilities as perceived by environmental health practitioners (EHPs).
Methods : A qualitative, constructivist study with a purposive sample of seven EHPs from Victoria, Australia, was conducted. A focus group discussion was guided by a semi‐structured interview schedule using open‐ended questions. The audio‐recorded focus group was transcribed verbatim and analysed using thematic analysis.
Results : Five themes represented the perceived barriers and enablers: i) pool water testing methods; ii) resources and training for EHPs; iii) knowledge and behaviour of aquatic facility operators and swimming pool users; iv) regulation; and v) aquatic facility and swimming pool design. Two key barriers within these themes included aquatic facility regulation and unhealthy swimming behaviours.
Conclusions : Several barriers and enablers to preventing and controlling Cryptosporidium spp. in aquatic facilities were perceived by EHPs. Suggestions to overcome perceived barriers were also identified. Further research is required to determine the impact of these findings on the incidence of cryptosporidiosis associated with aquatic facilities.
Implications for public health : The findings contribute to a greater understanding of the barriers and enablers to Cryptosporidium spp. prevention and control in aquatic facilities, which may improve the effectiveness of current prevention and control strategies.
... Water sources are another recognized cause of Campylobacter outbreaks, with numerous large-scale events involving ground and surface water being reported throughout Europe, North America, and New Zealand (Moreira et al., 2017). Although Australian estimates suggest 11% of campylobacteriosis cases are linked to water exposure (Gibney et al., 2017), the majority of waterborne outbreaks have involved recreational exposure to Cryptosporidium infections (Dale et al., 2010). Our study identified five waterborne outbreaks linked to drinking water, with four involving rainwater storage tanks and the fifth linked to bore water. ...
Campylobacter spp. are a globally important cause of bacterial gastroenteritis, with Australia experiencing higher rates of illness than many comparable high-income countries. Despite the high disease incidence, outbreaks of campylobacteriosis in Australia are infrequently detected and reported. We examined the epidemiology of Campylobacter outbreaks in Australia, with particular emphasis on assessing transmission routes and evidence as reported during public health investigations. A national register of enteric and foodborne disease outbreaks was used to summarize data on all Campylobacter outbreaks reported in Australia between 2001 and 2016. Outbreak data were reviewed and analyzed for trends over time. Additional information was sought from state and territory epidemiologists, to validate transmission routes. A total of 84 Campylobacter outbreaks were reported, with 51 (61%) being classified as foodborne. Specific food vehicles were identified for 33 (65%) outbreaks, with 28 (85%) implicating chicken or chicken-containing dishes. Although no increase in the proportion of foodborne Campylobacter outbreaks was observed, examination of specific food vehicles demonstrated a significant increase in outbreaks because of poultry-liver containing foods (p = 0.04). One quarter of all 1042 outbreak-associated cases occurred in aged-care facilities (ACFs), including 17 associated hospitalizations and three deaths. After review of evidence data, 23 outbreaks (27%) were determined to have an unknown route of transmission, including 10 (43%) outbreaks occurring in ACFs. Campylobacter spp. remain a less commonly reported cause of gastroenteritis outbreaks in Australia. Although many reported outbreaks can be linked to foodborne transmission, over a quarter were unable to identify either a food vehicle or transmission source, particularly for outbreaks occurring in aged care. Increased efforts to improve evidence collection and understanding of transmission dynamics for outbreaks of campylobacteriosis, particularly in aged care, are required.
... In Australia, more than 6500 gastroenteritis outbreaks were reported in the 7-year period 2001-2007, 54 of which were classified as waterborne, and 78% of these were associated with recreational water and 19% with drinking water. Salmonella sp. were the main bacterial pathogen followed by Campylobacter jejuni and Giardia (Dale et al., 2010). ...
We assessed the water quality of south-west Victorian rivers impacted by the dairy industry using traditional water quality assessment together with culture-dependent (colilert/enterolert) and also culture-independent (next generation sequencing) microbial methods. The aim of the study was to identify relationships/associations between dairy farming intensity and water contamination. Water samples with high total and faecal coliforms (>1000 MPN cfu/100 ml), and with high nitrogen levels (TN) were observed in zones with a high proportion of dairy farming. Members of the genus Nitrospira, Rhodobacter and Rhodoplanes were predominant in such high cattle density zones. Samples from sites in zones with lower dairy farming activities registered faecal coliform numbers within the permissible limits (<1000 MPN cfu/100 ml) and showed the presence of a wide variety of microorganisms. However, no bacterial pathogens were found in the river waters regardless of the proportion of cattle. The data suggests that using the spatially weighted proportion of land used for dairy farming is a useful way to target at-risk sub-catchments across south west Victoria; further work is required to confirm that this approach is applicable in other regions.
... From 2004 to 2010, 199 outbreaks of human gastroenteritis due to the waterborne transmission of 59 enteric parasitic protozoa were reported worldwide and of these, Cryptosporidium spp. was the etiological agent in 60.3% of the outbreaks [60,61]. Bathing in contaminated swimming and therapeutic pools is a major mode of waterborne transmission of Cryptosporidium and other pathogens [75]. ...
A growing number of people undertake international travel, and yet faster growth of such travel is expected in the tropics. Information on the hazards presented by pool and hot spring waters in tropical countries is very limited. This review aims to collate available information on pool water quality, alongside data on cases and outbreaks associated with swimming in pools in tropical regions affecting both local populations and travellers. Bacteria species commonly causing cases and outbreaks in the tropics as well as elsewhere in the world were excluded, and the review focuses on studies related to pathogens that, with the exception of Cryptosporidium, are unusual in more temperate climates. Studies concerning subtropical countries were included in the light of climate change. Diseases transmitted by vectors breeding in poorly maintained, neglected or abandoned pools were also included. 83 studies dealing with Microsporidia, Leptospira spp., Schistosomas spp., Cryptosporidium spp., Acanthamoeba spp., Naegleria spp., Clostridium trachomatis, viruses, and vectors breeding in swimming pool and hot tub waters, and fulfilling predefined criteria, have been included in our survey of the literature. In conclusion, prevention strategies for pool safety in the tropics are imperative. Public health authorities need to provide guidance to westerners travelling to exotic destinations on how to protect their health in swimming pools.
... There is a well-established link between Campylobacter infection and recreational water contact, 22,25,33 especially in outbreak situations. 12,34 Both fresh and sea water harbor Campylobacter spp. 35,36 and our study suggests that 4% of sporadic Danish campylobacteriosis cases may be caused by recreational water contact -even double that for children using a paddling pool. ...
Background
Each year more than 4,000 cases of campylobacteriosis are reported in Denmark, making it the most common bacterial gastrointestinal infection. Here we describe a case-control study to identify sources of infection with a focus on environmental factors.
Methods
From January to December 2016, we conducted a prospective case-control study among Danish persons aged 1–30 years. Participants were invited by letter to complete an online questionnaire. Crude and adjusted ORs were calculated and final parsimonious multivariate models developed using logistic regression.
Results
The study recruited 1366 cases and 4,418 controls, of whom 65% and 66%, respectively, completed the questionnaire. A multivariate model for domestically acquired cases showed, among others, increased risk of infection with bathing in fresh water (OR=5.1), contact to beach sand (OR=1.8), owning a pet dog with diarrhea (OR=4.6), and eating minced beef (OR=2.6) or chicken (OR=2.5). The model for children highlighted similar risk factors but also included bathing in a paddling pool (OR=13.6) and eating fresh strawberries (OR=5.3). A separate analysis for persons reporting foreign travel showed increased infection risk when traveling to Asia, Africa, or Turkey and that eating from street kitchens and having contact to water during traveling were also risk factors.
Conclusion
Environmental factors and animal contact account for a sizeable proportion of domestic Campylobacter infections in the age group studied. The study also re-confirmed handling/consumption of chicken as an important risk factor while highlighting minced beef as a potential new risk factor. Overall, these results contribute to a better understanding of the transmission dynamics of Campylobacter and will be used to improve national guidelines for prevention of infection.
... There are always potential risks when people drink untreated natural waters. The supply of clean water can become critical in areas of war, disaster, famine, drought, water shortage and flooding, and refugee supplies often need to be established rapidly to prevent outbreaks [36][37][38][39][40][41]. ...
Background: Water-related, including waterborne, diseases remain important sources of morbidity and mortality worldwide, but particularly in developing countries. The potential for changes in disease associated with predicted anthropogenic climate changes make water-related diseases a target for prevention. Methods: We provide an overview of evidence on potential future changes in water-related disease associated with climate change. Results: A number of pathogens are likely to present risks to public health, including cholera, typhoid, dysentery, leptospirosis, diarrhoeal diseases and harmful algal blooms (HABS). The risks are greatest where the climate effects drive population movements, conflict and disruption, and where drinking water supply infrastructure is poor. The quality of evidence for water-related disease has been documented. Conclusions: We highlight the need to maintain and develop timely surveillance and rapid epidemiological responses to outbreaks and emergence of new waterborne pathogens in all countries. While the main burden of waterborne diseases is in developing countries, there needs to be both technical and financial mechanisms to ensure adequate quantities of good quality water, sewage disposal and hygiene for all. This will be essential in preventing excess morbidity and mortality in areas that will suffer from substantial changes in climate in the future.
... Pathogenic organisms, including Aeromonas, Campylobacter, Legionella, Salmonella, Giardia and E. coli, have been found in rainwater harvested in many locations across Australia [12]. There have also been several reported outbreaks of salmonellosis, giardiasis and cryptosporidiosis that have been linked to contaminated rainwater [8, [13][14][15]. ...
In Australia, rainwater is an important source of water for many households. Unlike municipal water, rainwater is often consumed untreated. This study investigated the potential contamination of rainwater by microorganisms. Samples from 53 rainwater tanks across the Adelaide region were collected and tested using Colilert™ IDEXX Quanti-Tray*/2000. Twenty-eight out of the 53 tanks (53%) contained Escherichia coli. Samples collected from ten tanks contained E. coli at concentrations exceeding the limit of 150 MPN/100 mL for recreational water quality. A decline in E. coli was observed in samples collected after prolonged dry periods. Rainwater microbiological values depended on the harvesting environment conditions. A relationship was found between mounted TV antenna on rooftops and hanging canopies; and E. coli abundance. Conversely, there was no relationship between seasonality and E. coli or roof and tank structure materials and E. coli. In several tanks used for drinking water, samples collected prior to and after filtration showed that the filtration systems were not always successful at completely removing E. coli. These results differed from a study undertaken in the laboratory that found that a commercially available in-bench 0.45 µm filter cartridge successfully reduced E. coli in rainwater to 0 MPN/100 mL. After running a total of 265 L of rainwater which contained high levels of E. coli through the filter (half of the advertised filter lifespan), the filter cartridge became blocked, although E. coli remained undetected in filtered water. The difference between the laboratory study and field samples could be due to improper maintenance or installation of filters or recontamination of the faucet after filtration. The presence of E. coli in water that is currently used for drinking poses a potential health concern and indicates the potential for contamination with other waterborne pathogens.
... The first outbreak caused by Campylobacter was identified in Queensland [68], with a second linked to Salmonella identified in Victoria [74], and a third caused by Giardia lamblia identified in New South Wales [72] (see Table 6). Incidents of illness were recorded in aged care facilities and holiday camps [71]. ...
To address concern regarding water sustainability, the Australian Federal Government and many state governments have implemented regulatory mechanisms and incentives to support households to purchase and install rainwater harvesting systems. This has led to an increase in rainwater harvesting in regional and urban Australia. This review examines the implementation of the regulatory mechanisms across Australia. In addition, the literature investigating the potential health consequences of rainwater consumption in Australia was explored. Studies demonstrated that although trace metals such as arsenic, cadmium, chromium, lead, and iron were present in Australian rainwater, these metallic elements were generally found below the health limit guideline, except in high industrial areas. In addition, pathogenic or indicator microorganisms that include, but are not limited to, Escherichia coli , total and faecal coliforms, Campylobacter , Salmonella , Legionella , Pseudomonas , Cryptosporidium , Enterococci, Giardia , Aeromonas , and Mycobacterium avium Complex (MAC) have been detected in rainwater collected in Australia. However, epidemiological evidence suggests that drinking rainwater does not increase the risk of gastrointestinal disease. It was also identified that there is a need for further research investigating the potential for rainwater to be a source of infection for opportunistic pathogens.
... Surveillance systems such as FoodNet, National Notifiable Diseases Surveillance System (NNDSS), and National Outbreak Reporting System (NORS) by the US CDC, the Australian NNDSS, and similar systems by the European CDC (ECDC) and jurisdiction nations are in place in developed countries. Despite this, current outbreak detection methods lack sensitivity, specificity and timeliness i.e. there is a considerable lapse of time before an outbreak is recognised (Hellard et al., 2000;Dale et al., 2010;van de Venter et al., 2015). For example, in the Milwaukee outbreak in 1993, only a small number of cases were investigated prior to the identification of the outbreak and confirmation of its cause; similarly the 2011 outbreak in Skellefteå, Sweden, went unnoticed by authorities for months (Bjelkmar et al., 2017). ...
Foodborne illness, the majority of which is caused by enteric infectious agents, costs global economies billions of dollars each year. The protozoan parasite Cryptosporidium is particularly suited to foodborne transmission and is responsible for > 8 million cases of foodborne illness annually. Procedures have been developed for sensitive detection of Cryptosporidium oocysts on fresh produce and molecular diagnostic assays have been widely used in case linkages and infection source tracking, especially during outbreak investigations. The integrated use of advanced diagnostic techniques with conventional epidemiological studies is essential to improve our understanding of the occurrence, source and epidemiology of foodborne cryptosporidiosis. The implementation of food safety management tools such as Good Hygienic Practices (GHP), Hazard Analysis and Critical Control Points (HACCP), and Quantitative Microbial Risk Assessment (QMRA) in industrialized nations and Water, Sanitation, and Hygiene (WASH) in developing countries is central for prevention and control and foodborne cryptosporidiosis in the future.
... In addition to infections due to acknowledged pathogens, infections due to opportunistic microorganisms such as Mycobacterium fortuitum, Mycobacterium chelonei and Mycobacterium marinum are reported too which are able to cause mild to severe disease in immuno competent and immuno depressed individuals [7,8]. Most of the waterborne outbreaks of gastrointestinal diseases such as Salmonellosis have been associated with recreational exposure [9]. Approximately, 40% of the microorganism isolates from swimming pools are Bacillus which is due to the fact that they contain spores which are resistant to disinfecting substances. in the majority of cases, Bacillus subtilis is considered to be a non-pathogen but due to its dominant flora, under some special circumstances, it is thought to be the cause of conjunctivitis, meningitis, pneumonia and septicemia [10]. ...
Fifteen outdoor public swimming pools in Awka, Nigeria were assessed bacteriologically before and after use by bathers to determine their suitability for bathing purposes. The total bacterial, total coliform, faecal coliform, Staphylococcal and Pseudomonas counts were carried out using standard methods. The total bacterial count before and after use respectively was 10-160 cfu/ml and 100-280 cfu/ml; total coliform count, 3-87cfu/100ml and 40-120 cfu/100ml; Staphylococcal count, 0-70 cfu/ml and 0-169 cfu/ml while faecal coliforms and Pseudomonas were not detected in the samples. The bacteria were identified as klebsiella pneumoniae, Proteus mirabilis, klebsiella oxytoca, Enterobacter cloacae, Citrobacter freundii, Salmonella typhi, Bacillus licheniformis Staphylococcus aureus and Staphylococcus epidermidis. Klebsiella pneumoniae was detected in majority of the samples before and after use while Bacillus licheniformis, Citrobacter freundii and Salmonella typhi were each detected in one sample only before and after use. Klebsiella pneumoniae also had the highest occurence of 25.0% and 17.1% before and after use while Bacillus licheniformis had the lowest occurrence of 4.8% and 7.3% before and after use. None of the pools met the World Health Organization standard for coliforms therefore adequate and frequent treatment as well as regular bacteriological analyses of such pools are recommended.
... Water is also a vehicle for Campylobacter transmission, and several outbreaks have been linked to contaminated drinking water (Bartholomew, Brunton, Mitchell, Williamson, & Gilpin, 2014;Braaye, Schrijver, Wollants, van Ranst, & Verhaegen, 2015;DeFraites et al., 2014;Gubbels et al., 2012;Guzman-Herrador et al., 2015;Taylor et al., 2013;Unicomb, Fullerton, Kirk, & Stafford, 2009). Little is known about possible environmental sources, but sand, soil and water contaminated by animal faeces are all likely to play a role making outdoor activities potential risk factors -as also confirmed by Campylobacter outbreaks linked to hiking, mountain biking and water sports (Dale, Kirk, Sinclair, Hall, & Leder, 2010;Harder-Lauridsen, Kuhn, Erichsen, Mølbak, & Ethelberg, 2013;Stuart et al., 2010;Zeigler et al., 2014). ...
Campylobacter is the most frequently occurring cause of bacterial gastroenteritis in Europe. Unlike other zoonotic diseases, European-wide incidences of Campylobacter infections have increased during the past decade, resulting in a significant disease burden. In Denmark, campylobacteriosis is notifiable by laboratory and a unique registration system of electronic transfer and storage of notified Campylobacter cases linked to the national person register of age, gender and geographical location allows collection of comprehensive case data. Using national surveillance data, we describe Campylobacter infections in Denmark from 2000 to 2015, focusing on age-specific incidences, geography, seasonality and outbreaks. During the observed period, a total of 60,725 Campylobacter infections were registered with a mean annual incidence of 69.3 cases/100,000 population. From 2000 to 2014, the incidence of campylobacteriosis decreased by 20%, followed by an apparent increase of 20% from 2014 to 2015. Approximately one-third of cases were travel-related. Incidences were highest in males, young adults aged 20-29 years and children under 5 years of age. Generally, children under 10 years of age living in rural areas were at higher risk of infection. Infection patterns were seasonal with an increase from May to October, peaking in August. Outbreaks were identified each year, including four large waterborne outbreaks which all occurred following heavy rainfall events. For the most part, patterns of Campylobacter infection in Denmark during 2000 to 2015 remained remarkably constant and followed what is known about the disease with respect to demographic, temporal and spatial characteristics. To establish better targeted prevention and control measures, the current knowledge gaps regarding both Campylobacter microbiology (degree of clonal diversity and clustering) and the importance of different risk factors (food versus environment/climate) need to be filled.
... Outbreaks of gastroenteritis in Australia from recreational water exposure are far more common than those attributed to drinking water. In Australia, 42 reported gastroenteritis outbreaks linked to recreational water use were reported between 2001 and 2007, compared to 10 outbreaks that were linked to drinking water consumption (9). Therefore, the microbiological quality of recreational waters is of concern to water quality regulators and health departments. ...
Importance:
MST is an effective tool to help utilities and regulators improve the recreational water quality around the globe. Human fecal pollution poses significant public health risks compared to animal faecal pollution. Several human wastewater associated markers have been developed and used for MST field studies. However, a head to head comparison in terms of their performance to detect diluted human fecal pollution in recreational water is lacking. In this study, we cross compared the performance of six human wastewater associated markers in relation to FIB and enteric viruses in beach water samples seeded with raw and secondary treated wastewater. The results of this study will provide guidance to regulators and utlities on the appropriate application of MST markers for tracking the sources of human faecal pollution in environmental waters and confer human health risks.
... The higher incidence observed in rural cases in this study is most likely due to more frequent contact with animals and environmental exposures such as well water. Similar findings have been reported previously, as direct contact with farm animals [29,30], swimming in lakes and rivers [31], and drinking untreated water [32], were associated with a higher risk of campylobacteriosis in rural settings. The steep increasing rate observed in rural areas of Michigan is concerning and warrants a further investigation to identify the source of infection in these areas. ...
This study was conducted to examine the incidence trend of campylobacteriosis in Michigan over a 10-year period and to investigate risk factors and clinical outcomes associated with infection. Campylobacter case data from 2004 to 2013 was obtained from the Michigan Disease Surveillance System. We conducted statistical and spatial analyses to examine trends and identify factors linked to campylobacteriosis as well as ecological associations using animal density data from the National Agricultural Statistics Service. An increasing trend of Campylobacter incidence and hospitalization was observed, which was linked to specific age groups and rural residence. Cases reporting ruminant contact and well water as the primary drinking source had a higher risk of campylobacteriosis, while higher cattle density was associated with an increased risk at the county level. Additional studies are needed to identify age-specific risk factors and examine prevalence and transmission dynamics in ruminants and the environment to aid in the development of more effective preventive strategies.
... We recommend that LTCF residents not eat raw or undercooked eggs, due to the risk of contamination with Salmonella and the increased vulnerability of elderly people . In Australia, waterborne disease outbreaks are rarely reported in association with drinking water (Dale et al., 2010) and they are very rare in LTCF. While some studies did not find evidence that rainwater collected in tanks is associated with sporadic gastroenteritis (Heyworth et al., 2006), others have shown that they can become contaminated and cause human disease Franklin et al., 2009). ...
Elderly people are potentially at higher risk of gastroenteritis and foodborne diseases due to declining immunity, co-morbid illnesses and poorer food handling. In particular, residents of Long-Term Care Facilities (LTCF) have been highlighted as an 'at-risk' group, as outbreaks often occur in these facilities. The objectives of my research were to estimate the incidence of gastroenteritis and foodborne diseases in elderly Australians compared with other age groups, and elderly Australians living in LTCFs compared to elderly people in the community. I also examined the occurrence of outbreaks and causes of foodborne diseases in elderly people. To achieve these objectives I analyzed five different datasets: (1) a systematic review of gastroenteritis in LTCF residents, (2) 12-months longitudinal surveillance for gastroenteritis in residents of 16 LTCF in New South Wales, (3) two national surveys of gastroenteritis in the Australian community, (4)food- and waterborne infections in elderly people from Victorian public health surveillance, and (5) national surveillance of outbreaks of gastroenteritis and foodborne disease in Australian LTCF. I defined elderly people as 65 years or older. I analyzed datasets using meta-analysis, and negative binomial and logistic regression, depending on the nature of the data. In a meta-analysis of 15 international studies included in the systematic review, I estimated LTCF residents experience 0.15 episodes of gastroenteritis per person per year. Incidence was higher for studies conducted outside the United States at 0.27 episodes per person per year, which was similar to my findings of 0.23 episodes of diarrhea per person per year from longitudinal surveillance of 16 Australian LTCF. I estimated from national surveys that elderly people living in the community experienced 0.15 episodes of diarrhea per year, which was lower than any other age group. From Victorian surveillance data, the rate of Campylobacter infection in LTCF residents was 37!% lower than in community residents, after adjusting for age, gender and reporting period. However, Victorian LTCF residents were at higher risk of Salmonella infections, particularly in association with outbreaks. From longitudinal surveillance, 96% (245/254) of gastroenteritis episodes in LTCF residents were outbreak-associated. Analysis of 3,257 outbreaks of gastroenteritis that occurred in Australian LTCF over six years identified that 84,769 people were affected and facilities could expect one outbreak every three years. Outbreaks were predominantly transmitted from one infected person to another, with norovirus causing 35% (1,136/3,257) of outbreaks. Foodborne outbreaks were extremely rare and a food-vehicle was only identified in 27% (14/52) of outbreaks, where the main causes were meals that were pureed or contained eggs. In outbreaks of foodborne salmonellosis, 6.1% (15/244) of affected LTCF residents died. It was surprising to find that elderly people do not experience more gastroenteritis than younger people. Elderly people living in LTCF had a lower incidence of many foodborne infections than those living in the community, with the exception of salmonellosis. Gastroenteritis in LTCF residents was often associated with outbreaks, which were mainly spread from person-to-person. From these studies, health agencies should focus on identifying interventions to contain outbreaks of viral gastroenteritis in LTCF.
... Globally, waterborne microbial disease outbreaks have been directly associated with faecal pollution of urban estuaries (Jones, 2001, Worth & Biggs, 2003, Pond, 2005, Dale et al., 2010. ...
... Along with beneficial nutrients, PM commonly contains pathogenic bacteria, including Salmonella (SALM) ( Kraft et al., 1969;Rodriguez et al., 2006;Berghaus et al., 2013). Once released to the environ- ment, pathogens can be transported to recreational, irrigation, or drinking waters and pose a risk to human health ( Rogers and Haines, 2005;Craun et al., 2010;Dale et al., 2010;USEPA, 2013), or compromise the bio-security of poultry facilities (CDC, 2010;Castiglioni Tessari et al., 2012). ...
... The sanitary safety of drinking water has been of great concern in recent years [1] [2]. There have been many cases of public health issues caused by consumption of unsafe drinking water [3]. ...
Objectives: To identify the etiology and source after recognition of diarrhea outbreak is associated with drinking water in suburb of Chengdu. Methods: Both unmatched case control and retrospective cohort study were conducted. 131 targets including 56 suspected patients were recruited for case control study, while 463 residents were selected for cohort study. Stool, water and environmental samples were collected for laboratory testing. Results: The proportion of case exposed to well water was 86% in case group compared with 51% in the controls during the epidemic period (OR = 6.14, P P P E. coli and Enterotoxigenic E. coli was positive in stool and river samples. Conclusions: This outbreak of diarrhea might be caused by several mixed opportunistic pathogens in well water contaminated from the river water.
Treated recreational water facilities, including swimming pools and water play parks, have often been implicated in infectious disease outbreaks. Addressing this problem is complex due to the multiple and interrelated factors contributing to outbreaks in these settings. These factors may relate to inappropriate behaviours of users and operators, lack of and inconsistent regulation of these facilities, insufficient facility maintenance, and problems associated with the design of these facilities. Given the complexity of this issue, we argue that the Socio-Ecological Model (SEM) provides a useful framework to help identify the multi-level influences and factors that have implications for designing interventions to prevent this public health problem, whilst assisting in guiding future research in this area. We apply the SEM to the current literature to help identify the influences and factors contributing to infectious disease outbreaks in treated recreational water facilities to support this argument. We also identify several gaps in the existing research that would benefit from further examination to help prevent infectious disease outbreaks in treated recreational water facilities such as public swimming pools and water play parks.
As urban communities continue to grow, demand for recreational access (including swimming) in drinking water sources have increased, yet relatively little is understood about the public health implications this poses for drinking water consumers. Preventative risk-based approaches to catchment management, informed by quantitative microbial risk assessment (QMRA), requires accurate input data to effectively model risks. A sound understanding of the knowledge gaps is also important to comprehend levels of uncertainty and help prioritise research needs. Cryptosporidium is one of the most important causes of waterborne outbreaks of gastroenteritis globally due to its resistance to chlorine. This review was undertaken by Water Research Australia to provide the most up-to-date information on current Cryptosporidium epidemiological data and underlying assumptions for exposure assessment, dose response and risk assessment for generic components of QMRA for Cryptosporidium and highlights priorities for common research. Key interim recommendations and guidelines for numerical values for relatively simple screening level QMRA modelling are provided to help support prospective studies of risks to drinking water consumers from Cryptosporidium due to body-contact recreation in source water. The review does not cover site-specific considerations, such as the levels of activity in the source water, the influence of dilution and inactivation in reservoirs, or water treatment. Although the focus is Australia, the recommendations and numerical values developed in this review, and the highlighted research priorities, are broadly applicable across all drinking source water sources that allow recreational activities.
Inland recreational swimming sites provide significant social value globally. This study focused on public recreational swimming sites across the Murrumbidgee River and its tributaries in the Australian Capital Territory (ACT) throughout the swimming season (September–April) from 2009 to 2020 to determine whether high intestinal enterococci concentrations could be predicted with flow exceedance and routinely monitored physical and chemical parameters of water quality. Enterococci concentrations were positively correlated with the turbidity associated with high-flow conditions. The predictive accuracy of high enterococci levels during high-flow conditions was good (mean percentage correctly classified, 60%). The prediction of high enterococci levels at low flows was significantly less reliable (mean percentage correctly classified, 12–15%). As the ACT is expected to experience decreases in rainfall overall but increases in extreme rainfall events due to climate change, understanding the drivers of elevated intestinal enterococci under extreme flow conditions remains important from a public health perspective. HIGHLIGHTS
Climate change is anticipated to increase the frequency and magnitude of extreme rainfall.;
Extreme riverine flows were associated with high enterococci concentration.;
High flows and turbidity were good predictors of high enterococci concentrations.;
High enterococci during low flows were not well explained by the water quality or flow.;
The flagellated pathogen Giardia duodenalis is one of the leading causes of parasitic gastrointestinal illness worldwide. In many higher income countries, such as the United Kingdom, the disease is often perceived as being travel-related, likely leading to the under-reporting of sporadic cases and outbreaks. A summary of the literature describing outbreaks and risk factors in higher income countries is necessary to improve our understanding of this pathogen and identify existing knowledge gaps. Initial literature searches were carried out in September 2016 and updated at regular intervals until November 2021, using appropriate search terms in Medline, Embase and PubMed databases. A total of 75 papers met the inclusion criteria, revealing that the consumption of contaminated water and contact with young children of diaper-wearing age were the most common transmission routes leading to outbreaks of giardiasis. Of the ten studies where food was primarily associated with outbreaks, food handlers accounted for eight of these. Another reported transmission route was direct contact with fecal material, which was reported in six studies as the primary transmission route. Travel-associated giardiasis was considered the sole transmission route in two studies, whereas multiple transmission routes contributed to giardiasis outbreaks in eleven studies. The evidence around zoonotic transmission was less clear and hampered by the lack of robust and regularly applied parasite molecular typing techniques. This literature review summarizes the findings of Giardia outbreak investigations and epidemiological studies in high-income countries. Transmission routes are identified and discussed to highlight the associated risk factors. These data also indicate gaps in our current knowledge that include the need for robust, in-depth molecular studies and have underscored the importance of water as a transmission route for Giardia cysts. These future molecular studies will improve our understanding of Giardia epidemiology and transmission pathways in higher income countries to prevent spread of this significantly under-reported pathogen.
Background
Intensification of land use threatens to increase the emergence and prevalence of zoonotic diseases, with an adverse impact on human wellbeing. Understanding how the interaction between agriculture, natural systems, climate and socioeconomic drivers influence zoonotic disease distribution is crucial to inform policy planning and management to limit the emergence of new infections.
Objectives
Here we assess the relative contribution of environmental, climatic and socioeconomic factors influencing reported cryptosporidiosis across Australia from 2001 to 2018.
Methods
We apply a Bayesian spatio-temporal analysis using Integrated Nested Laplace Approximation (INLA).
Results
We find that area-level risk of reported disease are associated with the proportions of the population under 5 and over 65 years of age, socioeconomic disadvantage, annual rainfall anomaly, and the proportion of natural habitat remaining. This combination of multiple factors influencing cryptosporidiosis highlights the benefits of a sophisticated spatio-temporal statistical approach. Two key findings from our model include: an estimated 4.6% increase in the risk of reported cryptosporidiosis associated with 22.8% higher percentage of postal area covered with original habitat; and an estimated 1.8% increase in disease risk associated with a 77.99 mm increase in annual rainfall anomaly at the postal area level.
Discussion
These results provide novel insights regarding the predictive effects of extreme rainfall and the proportion of remaining natural habitat, which add unique explanatory power to the model alongside the variance associated with other predictive variables and spatiotemporal variation in reported disease. This demonstrates the importance of including perspectives from land and water management experts for policy making and public health responses to manage environmentally mediated diseases, including cryptosporidiosis.
In Hungary, which is famous for its thermal baths, according to the regulations, waters are investigated in hygienic aspects with standard cultivation methods. In the present study, two thermal baths were investigated (the well and three different pool waters in both) using cultivation methods, taxon-specific polymerase chain reactions (PCRs), multiplex PCRs and next-generation amplicon sequencing. Mainly members of the natural microbial community of the well waters and bacteria originating from the environment were detected but several opportunistic pathogenic taxa, e.g., Pseudomonas aeruginosa, P. stutzeri, Acinetobacter johnsoni, Acinetobacter baumanni, Moraxella osloensis, Microbacterium paraoxydans, Legionella spp., Stenotrophomonas maltophilia and Staphylococcus aureus were revealed by the applied methods. Pools with charging-unloading operation had higher microscopic cell counts, colony-forming unit (CFU) counts, number of cocci, P. aeruginosa and S. aureus compared to the recirculation systems. Bacteria originating from human sources (e.g., skin) were identified in the pool waters with less than 1% relative abundance, and their presence was sporadic in the pools. Comparing the microbiological quality of the pools based on the first sampling time and the following four months' period it was revealed that recirculation operation type has better water quality than the charging-unloading pool operation from a hygienic point of view.
Cryptosporidiosis, caused by infection with Cryptosporidium spp., is a globally distributed disease that manifests as diarrhoea for which there is no effective treatment. The protozoan parasite Cryptosporidium is difficult to detect and control, and can lead to severe disease in young children and the immunocompromised. Individual outbreaks across Australia have predominately been reported in urban areas associated with recreational water, but investigation of spatiotemporal distribution of disease is limited. This study evaluated the spatial and temporal patterns of clusters of notified cases of cryptosporidiosis in the north-eastern Australian state of Queensland, which has the highest average notified cases nationally. A spatiotemporal analysis in SaTScan of 12,263 notified cases from mid 2001 to mid 2015 identified 79 statistically significant disease clusters (P < 0.05). Analyses of annual incidence and disease cluster formation across the state illustrated the substantial randomness of clustering with no clear geographic distribution. Outbreaks were observed temporally across all latitudes and in rural and urban settings, with the majority of clusters centred in major and regional cities. Whilst clusters appeared in areas of high incidence, high incidence itself was not a predictor of clusters. Clusters generally formed during the hottest months between January and April, and cases were primarily children aged 0 to < 5 years. Spatiotemporal analysis at a statewide level is an important indicator of regional disease patterns and can act as a trigger for targeted epidemiological investigation.
Aims: This study aimed to describe the demographic and geographic patterns of campylobacteriosis in Denmark, Finland, Norway and Sweden during 2000–2015. Methods: All Campylobacter infections notified to national authorities in the four countries during the study period were included. Background data for each notification consisted of patient age, sex, geographical location, presumed origin of infection and date of sample taken or date of sample received in the laboratory. These data were analysed in order to investigate annual trends, age group and sex patterns, as well as variations in the geographical and seasonal distribution of infections. Results: During the study period, a total of 164,001 Campylobacter infections, excluding travel-related cases, were registered, representing a mean annual incidence of 42.3 cases/100,000 population (ranging from 28.5 in Norway to 60.4 in Denmark). The incidence increased significantly from 2004 onwards in all countries, apart from Denmark. Males had higher infection rates in general. The highest incidences were observed in 0–4 year olds and those aged 20–29 years, apart from in Finland where there was no peak of infections in children aged 0–4 years. Seasonality of disease was distinct in all four countries, showing peaks of infection between July and August. In Sweden and Norway, incidences of campylobacteriosis were significantly higher in municipalities with high degrees of coastline or inland water. Conclusions: Campylobacter in the Nordic countries mostly follows known patterns with respect to demography and seasonality. Our study demonstrates new insights concerning geographical patterns of disease, highlighting possible future vulnerable population groups and locations.
Salmonella is one of the leading causes of gastro-enteric disease in Canada, second only to Campylobacter. The mean exposure of Salmonella measured in cells ingested per person per day, from 15 transmission routes, including foodborne, animal contact and waterborne routes, was estimated for Canada using data inputs from 2005 to 2015. Chicken meat was estimated to have the highest exposure at 1.75E+00 cells/person/day. Other foodborne and waterborne transmission routes were roughly 3 log lower than the chicken meat exposure. Exposure at petting zoos and visiting a farm were at the bottom of the list at less than 1.00E-06 cells/person/day. Model output was most sensitive to the prevalence and concentration of contamination inputs, suggesting these are important areas for which more and better quality data need to be gathered. Chicken meat exposure exhibited no change when inputs modeled in a non log-linear manner, such as those related to cross-contamination and undercooking the food, were reduced by 10%. The results highlight the importance of chicken meat as an important route of exposure to Salmonella and provide further support for innovative efforts that advocate for public health interventions that reduce Canadians’ exposure to Salmonella along foodborne, animal contact and waterborne transmission routes.
At present, there are few technologies which enable the detection, identification and viability analysis of protozoan pathogens including Cryptosporidium and/or Giardia at the single (oo)cyst level. We report the use of Microfluidic Impedance Cytometry (MIC) to characterise the AC electrical (impedance) properties of single parasites and demonstrate rapid discrimination based on viability and species. Specifically, MIC was used to identify live and inactive C. parvum oocysts with over 90% certainty, whilst also detecting damaged and/or excysted oocysts. Furthermore, discrimination of Cryptosporidium parvum, Cryptosporidium muris and Giardia lamblia, with over 92% certainty was achieved. Enumeration and identification of (oo)cysts can be achieved in a few minutes, which offers a reduction in identification time and labour demands when compared to existing detection methods.
Cryptosporidium is the leading cause of swimming pool outbreaks of gastroenteritis. Transmission occurs through the ingestion of oocysts that are passed in the faeces of an infected person or animal when an accidental faecal release event occurs. Cryptosporidium parasites present specific challenges for infection control as oocysts are highly resistant to chlorine levels used for pool disinfection, infected individuals can shed large numbers of oocysts, there is a long incubation period and shedding of oocysts occurs even after symptom resolution. The purposes of this review are to identify key barriers to limiting swimming poolassociated outbreaks of cryptosporidiosis and to outline needs for research and collaboration to advance co-ordinated management practices. We reviewed swimming pool-associated cryptosporidiosis outbreaks, disinfection teachniques, current regulations and the role of staff and patrons. Key barriers to limiting swimming pool-associated outbreaks of cryptosporidiosis are a lack of uniform national and international standards, poor adherence and understanding of regulations governing staff and patron behaviour, and low levels of public knowledge and awareness.
Currently more than one billion people worldwide do not have access to safe drinking water or adequate sanitation. Important water-borne diarrhoeal diseases include cryptosporidiosis and giardiosis. Both in developed and developing countries, Cryptosporidium and Giardia are important causes of diarrhoea. This thesis aimed at studying (water-borne) transmission of Cryptosporidium and Giardia in Belgium and in Bangladesh.
The literature review (chapter 1) starts with introducing Cryptosporidium and Giardia, followed by an overview of their prevalence and clinical importance in both human and animals. Then the different transmission cycles of both parasites are discussed, including water-borne transmission through drinking water and recreational water. Finally, different methods for detecting and quantifying Cryptosporidium and Giardia in water are described.
In chapter 2, we monitored the presence of Cryptosporidium and Giardia in four drinking water catchment sites in Belgium. An attempt was made to determine the origin of (oo)cysts applying molecular tools. No contamination was found in purified drinking water at any site. In three catchments (Zillebeke, Gavers and Dikkebus), only low numbers of (oo)cysts were recovered from raw water samples. However, raw water samples from the Blankaart catchment site were frequently contaminated with Cryptosporidium and Giardia, especially in winter and spring. C. andersoni, C. suis, C. horse genotype, C. parvum and C. hominis and Giardia duodenalis assemblage AI, AII, BIV, BIV-like and E were identified. The genotyping results suggest that agriculture may be a more important source of surface water contamination than human waste in this catchment. Continuous monitoring of treated water for the presence of Cryptosporidium and Giardia would be justified and (point) sources of surface water contamination should be identified.
In chapter 3, the infection risk of Cryptosporidium and Giardia in recreational waters in Belgium was assessed in swimming pools, recreational lakes, splash parks and water fountains. The risk of Giardia infection in the swimming pools varied from 1.13x10-6 to 2.49x10-6 per swim per person. In recreational lakes the estimated infection risk varied from 2.79x10-5 to 5.74x10-5 per swim per person for Cryptosporidium and from 7.04x10-5 to 1.46 x10-4 for Giardia and for other outdoor water recreation activities the estimated infection risk was 5.71x10-6 for Cryptosporidium and 1.47x10-5 for Giardia. However, given that mainly animal-associated species/genotypes were identified and that the (oo)cyst viability was not assessed, the infection risk associated with recreational lakes may be overestimated. No Cryptosporidium was found in splash parks and water fountains, but the presence of Giardia cysts suggests a risk for human infection.
In chapter 4, we assessed the zoonotic and water-borne transmission of Cryptosporidium and Giardia in rural Bangladesh. High prevalences of Cryptosporidium and Giardia were found in both calves and their handlers, but genotyping results indicated that there was no zoonotic transmission between these two host populations. During monthly sampling of two village water ponds for two years, Cryptosporidium and Giardia were detected in 14/24 and 12/24 water samples respectively. Although the presence of Cryptosporidium and Giardia in both water ponds suggests that water-borne transmission of Cryptosporidium and Giardia is possible, genotyping results from infected village inhabitants and their cattle suggested no significant direct or indirect (water-borne) transmission of Giardia between cattle and people in this area of rural Bangladesh.
In chapter 5, we provided recommendations for water companies and outlined future studies on water-borne transmission both in Belgium and in Bangladesh.
Waterborne parasites that infect both humans and animals are common causes of diarrhoeal illness, but the relative importance of transmission between humans and animals and vice versa remains poorly understood. Transmission of infection from animals to humans via environmental reservoirs, such as water sources, has attracted attention as a potential source of endemic and epidemic infections, but existing mathematical models of waterborne disease transmission have limitations for studying this phenomenon, as they only consider contamination of environmental reservoirs by humans. This paper develops a mathematical model that represents the transmission of waterborne parasites within and between both animal and human populations. It also improves upon existing models by including animal contamination of water sources explicitly. Linear stability analysis and simulation results, using realistic parameter values to describe Giardia transmission in rural Australia, show that endemic infection of an animal host with zoonotic protozoa can result in endemic infection in human hosts, even in the absence of person-to-person transmission. These results imply that zoonotic transmission via environmental reservoirs is important.
Background:
Pathogenic intestinal protozoa infections are responsible for substantial mortality and morbidity, particularly in settings where people lack improved sanitation and safe drinking water. We assessed the relation between access to, and use of, sanitation facilities and water treatment and infection with intestinal protozoa.
Methods:
We did a systematic review and searched PubMed, ISI Web of Science, and Embase from inception to June 30, 2014, without restrictions on language. All publications were examined by two independent reviewers and were included if they presented data at the individual level about access or use of sanitation facilities or water treatment, in combination with individual-level data on human intestinal protozoa infections. Meta-analyses using random effects models were used to calculate overall estimates.
Findings:
54 studies were included and odds ratios (ORs) extracted or calculated from 2 × 2 contingency tables. The availability or use of sanitation facilities was associated with significantly lower odds of infection with Entamoeba histolytica or Entamoeba dispar (OR 0·56, 95% CI 0·42-0·74) and Giardia intestinalis (0·64, 0·51-0·81), but not for Blastocystis hominis (1·03, 0·87-1·23), and Cryptosporidium spp (0·68, 0·17-2·68). Water treatment was associated with significantly lower odds of B hominis (0·52, 0·34-0·78), E histolytica or E dispar (0·61, 0·38-0·99), G intestinalis (0·63, 0·50-0·80), and Cryptosporidium spp infections (0·83, 0·70-0·98).
Interpretation:
Availability and use of sanitation facilities and water treatment is associated with lower odds of intestinal protozoa infections. Interventions that focus on water and sanitation, coupled with hygiene behaviour, should be emphasised to sustain the control of intestinal protozoa infections.
Funding:
Swiss National Science Foundation (project numbers PBBSP3-146869 and P300P3-154634), Medicor Foundation, European Research Council (614739-A_HERO).
The objective of this study was to investigate the presence of Cryptosporidium and Giardia in different recreational water bodies in Belgium and to estimate the infection risk associated with swimming and other recreational activities. Cryptosporidium oocysts and/or Giardia cysts were detected in three out of 37 swimming pools, seven out of 10 recreational lakes, two out of seven splash parks and four out of 16 water fountains. In the swimming pools no infection risk for Cryptosporidium could be calculated, since oocysts were only detected in filter backwash water. The risk of Giardia infection in the swimming pools varied from 1.13 × 10(-6) to 2.49 × 10(-6) per swim per person. In recreational lakes, the infection risk varied from 2.79 × 10(-5) to 5.74 × 10(-5) per swim per person for Cryptosporidium and from 7.04 × 10(-5) to 1.46 × 10(-4) for Giardia. For other outdoor water recreation activities the estimated infection risk was 5.71 × 10(-6) for Cryptosporidium and 1.47 × 10(-5) for Giardia. However, most positive samples in the recreational lakes belonged to species/genotypes that are either animal-specific or predominantly found in animals. No Cryptosporidium was found in splash parks and water fountains, but the presence of Giardia cysts suggests a risk for human infection. The infection risk of Giardia infection during a 3.5-minute visit to a splash park for children equalled 1.68 × 10(-4).
Campylobacter infection usually causes enteritis, the nosological spectrum of which varies from watery, non-bloody diarrhea to severe inflammatory diarrhea with abdominal pain and fever. Bacteremia, Reiter syndrome, Guillain-Bar-ré syndrome and hemolytic uremic syndrome are possible complications of this infection, which can also cause localized infections, such as meningitis and encephalitis, especially in children. Campylobacter infection is transmitted through the consumption of contaminated food or water. The incubation period of the disease is usually two to five days and the transmission period lasts throughout the duration of infection, usually from a few days to a few weeks. According to the most recently published data of the European Centre for Diseases Control and Prevention, the overall incidence of the disease among the 25 countries of the European Union was 44.1 cases per 100,000 population in 2008, and Campylobacter spp was the most frequently reported bacterial cause of acute gastroenteritis and also the most frequently isolated pathogen in stool cultures, surpassing Salmonella spp. In Greece, the surveillance of the disease is voluntary and the available epidemiological data are limited. Risk factors for Campylobacter infection are consumption of poultry, red meat, unpasteurized milk or untreated water, swimming, travelling abroad, contact with animals, consumption of omeprazole or H2 inhibitors, the presence of an underlying condition, etc. The contribution of each of these factors to disease morbidity varies according to the particular characteristics of the population. Only a limited number of analytical epidemiological studies have been conducted in Southern Europe, one of which refers to the urban population of children in Greece. In summer 2009 an outbreak of campylobacteriosis with 54 recorded cases was reported to the Greek public health authorities for the first time. Consequently, it is important for clinicians to be well-informed about the recent epidemiological data of the disease, in order to increase the frequency of laboratory investigation of gastroenteritis cases for Campylobacter spp. In this way, the public health authorities will be able to investigate cases of Campylobacter infection more actively.
Abstract Objective: To establish the incidence and aetiology of infectious intestinal disease in the community and presenting to general practitioners. Comparison with incidence and aetiology of cases reaching national laboratory based surveillance.
Design: Population based community cohort incidence study, general practice based incidence studies, and case linkage to national laboratory surveillance.
Setting: 70 general practices throughout England.
Participants: 459 975 patients served by the practices. Community surveillance of 9776 randomly selected patients.
Main outcome measures: Incidence of infectious intestinal disease in community and reported to general practice.
Results: 781 cases were identified in the community cohort, giving an incidence of 19.4/100 person years (95% confidence interval 18.1 to 20.8). 8770 cases presented to general practice (3.3/100 person years (2.94 to 3.75)). One case was reported to national surveillance for every 1.4 laboratory identifications, 6.2 stools sent for laboratory investigation, 23 cases presenting to general practice, and 136 community cases. The ratio of cases in the community to cases reaching national surveillance was lower for bacterial pathogens (salmonella 3.2:1, campylobacter 7.6:1) than for viruses (rotavirus 35:1, small round structured viruses 1562:1). There were many cases for which no organism was identified.
Conclusions: Infectious intestinal disease occurs in
1 in 5 people each year, of whom 1 in 6 presents to a general practitioner. The proportion of cases not recorded by national laboratory surveillance is large and varies widely by microorganism.Ways of supplementing the national laboratory surveillance system for infectious intestinal diseases should be considered.
Public health surveillance requires the monitoring of waterborne disease, but sensitive and specific detection of relevant incidents is difficult.
The Communicable Disease Surveillance Centre receives information from various sources about clusters of cases of illness in England and Wales. The reporter may suspect that water consumption or recreational water exposure is the route of infection, or subsequent investigation may raise the hypothesis that water is associated with illness.
It is difficult to prove beyond reasonable doubt that such a hypothesis is correct. Water samples from the time of exposure are seldom available, some organisms are difficult to detect and almost everyone has some exposure to water. Therefore, we have developed a method of categorizing the degree of evidence used to implicate water. The categories take into account the epidemiology, microbiology and water quality information. Thus outbreaks are classified as being associated with water either ‘strongly’, ‘probably’ or ‘possibly’.
This system allows a broad database for monitoring possible effects of water and is not confined to the few outbreaks which have been intensively investigated or have positive environmental microbiology. Thus, for reported incidents, the sensitivity of classifying it as water associated should be high but this may be at the expense of specificity, especially with the ‘possible’ association.
Published data on infection of human hosts with various protozoa, bacteria, and viruses causing gastro-enteritis are used to establish a quantitative relationship between ingested dose and the risk of infection. For all data sets analysed, this relationship is determined by fitting either an exponential curve or a beta-poisson curve. These relationships can e.g. be applied to assess the risk of infection associated with drinking water or consumption of food contaminated with a low dose of an infectious pathogen. Gepubliceerde gegevens omtrent infectie van humane proefpersonen met pathogene micro-organismen die gastro-enteritis veroorzaken (protozoa, bacterien en virussen), worden gebruikt om een kwantitatieve relatie vast te stellen tussen de ingenomen dosis en het risico op infectie. Voor alle bestudeerde datasets wordt deze relatie bepaald door het fitten van een exponentiele curve dan wel een beta-poisson curve. Deze relaties kunnen b.v. worden toegepast bij het vaststellen van het risico op infectie bij inname van drinkwater of voedsel dat is verontreinigd met een kleine hoeveelheid van een infectieus pathogeen.
In May 2000, bacterial contamination of municipal water in Walkerton, Ontario, resulted in the worst public health disaster involving municipal water in Canadian history. At least seven people died and 2300 became ill. A public inquiry led by judge Dennis O'Connor examined the events and delineated the causes of the outbreak, including physical causes, the role of the public utilities operators, the public utilities commissioners, the Ministry of the Environment (MOE), and the provincial government. Improper practices and systemic fraudulence by the public utility operators, the recent privatization of municipal water testing, the absence of criteria governing quality of testing, and the lack of provisions made for notification of results to multiple authorities all contributed to the crisis. The MOE noted significant concerns 2 years before the outbreak; however, no changes resulted because voluntary guidelines as opposed to legally binding regulations governed water safety. The inquiry concluded that budgetary restrictions introduced by the provincial government 4 years before the outbreak were enacted with no assessment of risk to human health. The ministers and the cabinet had received warnings about serious risks. Budgetary cuts destroyed the checks and balances that were necessary to ensure municipal water safety.
The incidence of acute gastroenteritis and self suspected food poisoning in general practice populations was compared with consultation rates in four group practices during a 3-month winter period and a 2-month autumn period. The average monthly consultation rate for acute gastroenteritis and self suspected food poisoning was 0.3% and 0.06% respectively. However, over the same period, on average, an estimated 7% of the practice population per month reported an acute gastroenteritis illness, and 0.7% suspected a food poisoning illness. Only about one in 26 people who suffer an acute episode of gastroenteritis consult their general practitioner (GP). In two practices, faecal samples were sought from all patient cases; the isolation rate for salmonellas was 2% (3/191) and for campylobacters it was 12% (23/191). In the other two practices following routine management, the isolation rate for salmonellas was 9% (6/64) and for campylobacters it was 2% (1/64). Isolation of faecal pathogens was not associated with patients' suspicion of food poisoning. A history of eating out in the week before onset was associated with a significantly increased yield of salmonellas and campylobacters.
To establish the incidence and aetiology of infectious intestinal disease in the community and presenting to general practitioners. Comparison with incidence and aetiology of cases reaching national laboratory based surveillance.
Population based community cohort incidence study, general practice based incidence studies, and case linkage to national laboratory surveillance.
70 general practices throughout England.
459 975 patients served by the practices. Community surveillance of 9776 randomly selected patients.
Incidence of infectious intestinal disease in community and reported to general practice.
781 cases were identified in the community cohort, giving an incidence of 19.4/100 person years (95% confidence interval 18.1 to 20.8). 8770 cases presented to general practice (3.3/100 person years (2.94 to 3.75)). One case was reported to national surveillance for every 1.4 laboratory identifications, 6.2 stools sent for laboratory investigation, 23 cases presenting to general practice, and 136 community cases. The ratio of cases in the community to cases reaching national surveillance was lower for bacterial pathogens (salmonella 3.2:1, campylobacter 7.6:1) than for viruses (rotavirus 35:1, small round structured viruses 1562:1). There were many cases for which no organism was identified.
Infectious intestinal disease occurs in 1 in 5 people each year, of whom 1 in 6 presents to a general practitioner. The proportion of cases not recorded by national laboratory surveillance is large and varies widely by microorganism. Ways of supplementing the national laboratory surveillance system for infectious intestinal diseases should be considered.
The infectivity of three Cryptosporidium parvum isolates (Iowa [calf], UCP [calf], and TAMU [horse]) of the C genotype was investigated in healthy adults. After exposure,
volunteers recorded the number and form of stools passed and symptoms experienced. Oocyst excretion was assessed by immunofluorescence.
The ID50 differed among isolates: Iowa, 87 (SE, 19; 95% confidence interval [CI], 48.67–126); UCP, 1042 (SE, 1000; 95% CI, 0–3004);
and TAMU, 9 oocysts (SE, 2.34; 95% CI, 4.46–13.65); TAMU versus Iowa, P = .002 or UCP, P = .019. Isolates also differed significantly (P = .045) in attack rate between TAMU (86%) and Iowa (52%) or UCP (59%). A trend toward a longer duration of diarrhea was seen
for the TAMU (94.5 h) versus UCP (81.6 h) and Iowa (64.2 h) isolates. C. parvum isolates of the C genotype differ in their infectivity for humans.
To estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001-2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17.2 million (95% CI 14.5-19.9 million) cases of gastroenteritis in Australia in one year, or 0.92 (95% CI 0.77-1.06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.
We reviewed the epidemiological and microbiological characteristics of 89 reported outbreaks of waterborne infectious intestinal disease affecting 4321 people in England and Wales over the period 1992-2003. Public water supplies were implicated in 24 outbreaks (27%), private water supplies in 25 (28%), swimming pools in 35 (39%) and other sources in five outbreaks (6%). Cryptosporidium was implicated in 69% of outbreaks, Campylobacter sp. in 14%, Giardia in 2%, E. coli O157 in 3% and Astrovirus in 1%. From 2000, there was a consistent decline in the number of outbreaks of waterborne disease associated with public water supplies. The incidence rate of outbreaks in recipients of private water supplies may be as high as 35 times the rate in those receiving public water supplies (1830 vs. 53 per million population). Private water suppliers need to be aware of the importance of adequate treatment and the prevention of faecal contamination of storage water. Swimming-pool operators need to ensure chlorination and in particular adequate filtration measures are in place.
Epidemic waterborne risks are discussed in this paper. Although the true incidence of waterborne illness is not reflected in the currently reported outbreak statistics, outbreak surveillance has provided information about the important waterborne pathogens, relative degrees of risk associated with water sources and treatment processes, and adequacy of regulations. Pathogens and water system deficiencies that are identified in outbreaks may also be important causes of endemic waterborne illness. In recent years, investigators have identified a large number of pathogens responsible for outbreaks, and research has focused on their sources, resistance to water disinfection, and removal from drinking water. Outbreaks in surface water systems have decreased in the recent decade, most likely due to recent regulations and improved treatment efficacy. Of increased importance, however, are outbreaks caused by the microbial contamination of water distribution systems. In order to better estimate waterborne risks in the United States, additional information is needed about the contribution of distribution system contaminants to endemic waterborne risks and undetected waterborne outbreaks, especially those associated with distribution system contaminants.
An outbreak of Campylobacter enteritis among staff on a resort island in north Queensland is reported. Untreated rainwater and food from the staff dining room were initially suspected as possible sources of infection but Campylobacter species were not isolated from any environmental samples. Faecal contamination was detected in four rainwater tanks. A case control study involved a total of 23 cases (7 confirmed and 16 probable), 3 of whom required hospitalisation. There was a strong association between gastrointestinal illness and consumption of water from a dispenser in the staff restaurant that had probably been filled from one of the contaminated tanks. We conclude that this was probably a waterborne outbreak and postulate that Campylobacter species were introduced into one or more of the tanks by contamination with the faeces of wild animals.
A review of the incidence of waterborne disease in Scotland from 1945 to 1987 has been undertaken in conjunction with the Communicable Diseases (Scotland) Unit and the Scottish Home and Health Department. Primarily, these relate to contamination of private and public supplies by microbiological and chemical agents, but incidents in which water such as river water was ingested deliberately or accidentally were included. Water-related infections such as legionellosis and leptospirosis which are acquired by non-alimentary routes have been excluded. During the period of the review there were 57 outbreaks of water-borne disease comprising of over 15,305 cases of illness. A total of 18 outbreaks occurred in public supplies and 21 in private supplies. Microbiological contamination gave rise to the greatest number of cases of water-borne disease which were caused by viral gastroenteritis and shigellosis followed by outbreaks of gastroenteritis of unknown aetiology.
The highest number of outbreaks were due to chemical poisoning,caused mainly by lead and copper, followed by outbreaks of gastroenteritis of unknown aetiology. The type of deficiency giving rise to incidents of waterborne disease were described for private and public water supplies. In public supplies the need for hygenic storage of water in distribution and effective catchment control practices in conjunction with adequate water treatment facilities is emphasised. In private supplies the need to, at minimum, apply rudimentary disinfection to untreated source water is highlighted by the large numbers of people who have been affected by water-borne disease.
In this article, we review the causes of 212 recreational waterborne outbreaks and 17,975 cases of illness reported in U.S.A. during 1995-2004. Gastroenteritis was the most frequently (91%) reported illness. Conditions or symptoms related to the skin, ears, or eyes occurred less frequently (6%). Also reported were cases of leptospirosis, acute respiratory illness, meningitis, and primary amebic meningoencephalitis. A bacterial or protozoan etiology was identified in most (71%) outbreaks; 8% of the outbreaks were viral in origin. An etiology was not confirmed for 17% of the outbreaks. Cryptosporidium spp., Pseudomonas aeruginosoa, norovirus, and chemicals were confirmed as the cause of most (69%) outbreaks in treated recreational waters such as swimming and wading pools. Naegleria fowleri, E. coli O157:H7, norovirus, Shigella spp., and avian Schistosomatidae were confirmed as the cause of most (72%) outbreaks in untreated recreational waters such as lakes, ponds, and streams. Bathers themselves were the most important sources of contamination (e.g, fecal accidents, bathing while ill, large numbers of bathers) for outbreaks in both treated and untreated recreational waters. Sewage discharges, watershed runoff during heavy rainfall, algal blooms, and various animal and avian species were also important sources of contamination for untreated recreational waters. Inadequate operation, maintenance, or water treatment was an important contributing risk factor for outbreaks in treated recreational waters. Waterborne outbreak surveillance can help identify the etiologic agents, sources of contamination, and treatment/operational deficiencies so that effective prevention and control programs can be implemented. However, the outbreak statistics may not accurately reflect the risks of sporadic or endemic waterborne illness associated with recreational activities in fresh and marine waters. Information from epidemiologic studies that are now being conducted can lead to guidelines to reduce endemic illness risks.
Provides the latest QMRA methodologies to determine infection risk cause by either accidental microbial infections or deliberate infections caused by terrorism. Reviews the latest methodologies to quantify at every step of the microbial exposure pathways, from the first release of a pathogen to the actual human infection. Provides techniques on how to gather information, on how each microorganism moves through the environment, how to determine their survival rates on various media, and how people are exposed to the microorganism. Explains how QMRA can be used as a tool to measure the impact of interventions and identify the best policies and practices to protect public health and safety. Includes new information on genetic methods. Techniques use to develop risk models for drinking water, groundwater, recreational water, food and pathogens in the indoor environment.
When pathogenic microorganisms enter the human body via ingestion of food or drinking water, they encounter a system of barriers mounted by the host. Defense mechanisms against microbial infection and invasion may be immunological or non-immunological. To reach parts of the intestinal tract that are suitable for growth and attachment, they must overcome each of the barriers successfully. According to the present view on infection, at least one of the ingested pathogens must survive if colonization is to start. This is the basis for dose response models used for quantitative risk assessment. The validity of such a model, the Beta Poisson model, was demonstrated for multiple barriers, with some attention being given to the single-hit principle. Also discussed was an approach to the derivation of the Beta Poisson model, an aspect which is usually neglected. This approach was shown here to produce results for certain parameter values that were different from the exact formula. Finally, several initiatives for new models are presented in which extra information on infection and illness is incorporated. Pathogene micro-organismen die het menselijk lichaam binnendringen via voeding of door het drinken van besmet water, krijgen te maken met een door de gastheer opgeworpen systeem van barrieres. Teneinde delen van het spijsverteringskanaal te bereiken die geschikt zijn voor groei en hechting, moet elk van de tussenliggende barrieres overwonnen worden. De gangbare visie op infectie gaat ervan uit dat minstens een van de ingeslikte pathogenen moet overleven om te kunnen koloniseren. Dit is de basis voor dosis-responsmodellen zoals toegepast bij de microbiologische risico-analyse. Afweermechanismen tegen infectie en invasie door micro-organismen kunnen immunologisch zijn of non-immunologisch. In dit rapport wordt de geldigheid van het Beta-Poissonmodel voor meer dan een barriere gedemonstreerd en wordt enige aandacht besteed aan het 'single-hit' principe. Ook besproken wordt een benadering in de afleiding van het Beta-Poissonmodel, en aangetoond wordt dat deze benadering voor bepaalde parameterwaarden resultaten oplevert die verschillen van de exacte formule. Tenslotte worden enkele aanzetten gedaan tot modellen, waarbij extra informatie over infectie en ziekte kan worden gebruikt.
Sources of information for monitoring infectious disease are routine data, special surveys and ad hoc investigations. In practice much use is necessarily made of routine notifications and laboratory records although this reporting is often incomplete and may therefore be biased.
In a retrospective study of a 16-year series (up to 1968) of routine records concerning the diagnosis of gastroenteritis at one Public Health Laboratory we found it possible to identify biases. During school outbreaks of dysentery, laboratory investigation of diarrhoea increased appreciably and such response to publicity affects the use of routine data in surveillance. Although the patients examined were probably representative diagnostically, their selection may not have reflected the age incidence of disease. Valid geographical comparisons within the urban area were not feasible because medical practitioners differed in their use of laboratory facilities and in their habits of notification. Nevertheless, as far as can be established retrospectively, these data did reflect time trends in disease incidence and so had value for monitoring purposes.
Several of the biases defined are likely to apply to other sets of routine data. A further communication will describe a statistical method of correcting for quantifiable bias.
An outbreak of Campylobacter enteritis among staff on a resort island in north Queensland is reported. Untreated rainwater and food from the staff dining room were initially suspected as possible sources of infection but Campylobacter species were not isolated from any environmental samples. Faecal contamination was detected in four rainwater tanks. A case control study involved a total of 23 cases (7 confirmed and 16 probable), 3 of whom required hospitalisation. There was a strong association between gastrointestinal illness and consumption of water from a dispenser in the staff restaurant that had probably been filled from one of the contaminated tanks. We conclude that this was probably a waterborne outbreak and postulate that Campylobacter species were introduced into one or more of the tanks by contamination with the faeces of wild animals.
When pathogenic microorganisms enter the human body via ingestion with food or drinking water, they encounter a system of barriers mounted by the host. In order to reach parts of the intestinal tract that are suitable for growth and attachment, each of the barriers must be overcome successfully. The present view on infection states that at least one of the ingested pathogens must survive to start colonization. This is the basis for dose response models, used for quantitative risk assessment. In this paper, the usefulness of the Beta Poisson model for multiple barriers is corroborated. Infection is associated with the presence of elevated numbers of reproducing pathogens in the intestinal tract. This does not necessarily imply illness symptoms: when intestinal microorganisms engage in damaging activities, this may lead to illness symptoms. At the same time, these activities probably elicit defensive measures from the host, promoting the removal of pathogens and terminating infection. The duration of the period of colonization reflects the balance between the colonization potential of pathogens and the strength of host defenses. Starting from the assumption that during infection the host has a certain hazard of becoming ill, a simple dose response relation for acute gastroenteritis is developed. With the use of literature data from volunteer experiments, we show that examples can be found for three possible alternatives: an increase in the probability of illness with increasing dose, a decrease with higher doses, and a probability of illness (given infection) independent of the ingested dose. These alternatives may reflect different modes of interaction between pathogens and host.
To describe an outbreak of Cryptosporidium gastroenteritis in a swimming pool in Melbourne in early 1998 that was not detected through routine surveillance, and discuss difficulties in identifying such outbreaks.
The Water Quality Study (WQS) was a large community-based study of gastroenteritis. Following suspicion of an outbreak of cryptosporidiosis within the study group, due to pool "X", a nested case control study was performed. Each case of Cryptosporidium gastroenteritis was matched with six controls and data from weekly Health Diaries from the WQS were reviewed. The Department of Human Services also instigated active surveillance among patrons at pool "X" using a systematic sample of 50 people from the pool's swim-school enrollment list.
There were seven cases of Cryptosporidium gastroenteritis in the case control study. Five cases and eight controls swam at pool "X" during the outbreak period. The adjusted odds of developing cryptosporidial diarrhoea if an individual swam at pool "X" was 34.5 (CI 2.3-2548). DHS identified another 11 laboratory confirmed cases associated with pool "X" as well as cases not linked to pool "X". 125 cases were identified throughout Melbourne with the suspected involvement of seven swimming pools.
Despite a high odds ratio of developing cryptosporidiosis this outbreak was not detected by routine surveillance methods. Current outbreak detection methods lack sensitivity, specificity or timeliness.
Improved surveillance systems are required if outbreaks of gastroenteritis are to be detected early so an intervention can be instigated to reduce the amount of subsequent illness.
Contamination of a tank water supply system led to an outbreak of Salmonella Saintpaul with 28 cases of gastroenteritis amongst over 200 workers at a large construction site. The outbreak was identified following notification of two salmonellosis cases by general practitioners from different towns during March 1999. The source of infection, contaminated drinking water, was identified through environmental sampling and confirmed by epidemiological investigations. Frogs and/or mice may have been the original source of the contamination. This report details control measures, the results of investigations and recommendations for future research.
This article is a summary of discussions held and recommendations made at a workshop for the investigation of waterborne disease outbreaks in Chapel Hill, North Carolina, December 7-8, 1998. Suspected waterborne outbreaks in the United States are primarily investigated by state and local public health officials who may infrequently conduct enteric disease outbreak investigations. Thus, it is important that officials have a formal plan to ensure that epidemiological studies are methodologically sound and that effective collaboration occurs among the epidemiologists, scientists, and engineers who will conduct the investigations. Laboratory support to analyze water samples and clinical specimens should be arranged well in advance of when services may be needed. Enhanced surveillance activities can help officials recognize additional outbreaks and initiate investigations in a timely manner. Epidemiologists should pay more attention early in the investigation to study design, questionnaire development, and sources of bias, especially recall bias, that may affect the interpretation of observed associations. Improved investigations can increase our knowledge about important etiological agents, water systems deficiencies, and sources of water contamination so that waterborne outbreaks can be more effectively prevented.
National Water Quality Management Strategy, Implementation Guidelines. Canberra (AUST): Commonwealth Department of the Environment, Water, Heritage and the Arts
- New Australian
- Zealand Environment
- Conservation Council
Australian and New Zealand Environment and Conservation Council. National Water Quality Management Strategy, Implementation Guidelines. Canberra (AUST): Commonwealth Department of the Environment, Water, Heritage and the Arts; 1998.