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Assessment of Enteric Pathogen Shedding by Bathers during Recreational Activity and its Impact on Water Quality
Abstract
An assessment was made to determine the potential loading of enteric pathogenic protozoa and viruses into drinking water supply reservoirs by body contact recreation. These and other organisms of fecal origin are shed from the body during bathing. A literature review was conducted on the concentration of selected enteric viruses and protozoa during infection, the incidence of these infections, and duration of excretion. In addition, from existing literature, the amount of fecal material released during bathing was estimated from the shedding of fecal coliforms by bathers. The mean amount of fecal material shed per bather was estimated at 0.14[emsp4 ]gram. The concentration of protozoan parasites (Giardia or Cryptosporidium) in feces of infected persons can range from 105 to 107 per gram and enteric viruses (enteroviruses, adenoviruses, rotavirus) from 105 to 1012 per gram. From this information, the concentration of enteric pathogens, shed into the water, could be calculated for a group of bathers. This information can be used to model the impact of body contact recreation on water quality in reservoirs used for drinking water supplies. Such information is useful in assessing the required treatment of the water to meet water quality regulations.
... Les activités de baignade sont considérées comme une source directe de bactéries fécales. En effet, un apport de 100 g de fèces permet la dissémination de 10 14 cellules de pathogènes dans la colonne d'eau ; et en moyenne un baigneur peut apporter 0.14 g de matière fécale durant une baignade de 15 minutes (Gerba, 2000). Les activités de loisirs comme les campings non raccordés aux STEP, les plaisanciers rejetant les eaux noires « non traitées » des bateaux au niveau ou au large des plages, peuvent contribuer à l'apport de microorganismes fécaux dans ces environnements . ...
... Dans les matières fécales, les virus entériques peuvent atteindre une concentration de 10 5 à 10 12 particules virales par gramme de fèces (Gerba, 2000 (Gerba, 2000;Hartard, 2017;Maunula et al., 2013;Pina et al., 1998;Wong et al., 2012). Par exemple, les norovirus et les adénovirus sont les principaux indicateurs de la qualité microbiologique des fruits de mer comme les huîtres (Maunula et al., 2013;Wong et al., 2012). ...
... Dans les matières fécales, les virus entériques peuvent atteindre une concentration de 10 5 à 10 12 particules virales par gramme de fèces (Gerba, 2000 (Gerba, 2000;Hartard, 2017;Maunula et al., 2013;Pina et al., 1998;Wong et al., 2012). Par exemple, les norovirus et les adénovirus sont les principaux indicateurs de la qualité microbiologique des fruits de mer comme les huîtres (Maunula et al., 2013;Wong et al., 2012). ...
La qualité microbiologique des eaux de baignade diminue progressivement d’années en années, et peut être un problème majeur de santé publique. Ainsi, des surveillances sanitaires de la qualité microbiologique des eaux de baignade sont effectuées conformément à la directive européenne (2006/7/EC) pour assurer la sécurité sanitaire des baigneurs et préserver l’image de ces écosystèmes. Depuis de nombreuses années, la baie d’Aytré (Charente Maritime, France), a été classée en « qualité insuffisante » et cette plage est interdite à la baignade depuis 2018. Les enjeux sanitaires et le rôle prépondérant de cette plage sur le développement touristique et l’économie locale ont conduit à rechercher l’origine et le déterminisme spatiotemporel de cette contamination fécale. Cette thèse présente une approche intégrée de l’analyse de la contamination fécale de la baie d’Aytré par une étude pluridisciplinaire de différentes hypothèses analysées depuis le début des années 2000 par les collectivités locales. Le niveau de contamination fécale des eaux de baignade durant une année était relativement faible avec une variation saisonnière notable de l’abondance des indicateurs de contamination fécale Escherichia coli et entérocoques. Les dépassements des seuils réglementaires sur 24% et 32% des échantillons d’eau du Platin Nord et du Platin Sud, les deux sites de baignade de la baie d’Aytré étaient principalement dus aux entérocoques. La qualité microbiologique du sédiment au cours du temps a montré que le sédiment n’était pas une source diffuse de contamination dans l’eau. L’analyse combinée des marqueurs protéiques, génétiques et chimiques a révélé la présence d’une part d’espèces d’entérocoques d’origine environnementale et d’autre part une contamination d’origine animale principalement et une faible contribution de l’origine humaine. La stratégie d’analyse élaborée et les outils développés au cours de cette étude permettront d’améliorer les méthodes de surveillance sanitaire des eaux de baignade
... This behavior pattern is accepted widely around the world (Dagevos & Voordouw, 2013). It is expected that by 2030 the demand for food of animal origin will be more than 50% compared to 2000(van Wagenberg et al., 2017 and according to Derner et al. (2017) the animal production should increase by 70% by 2050 to satisfy consumers' demands for meat and muscle products. This increase in demands requires the changes in the current livestock production patterns, which should be able to avoid extra pressure on the ecosystem, and aim for the "sustainability." ...
... Enteric viruses have fecal-oral route and are excreted in diarrheic feces in large concentrations (up to 10 11 viral particles per g) (Gerba, 2000). They have low infective doses (1-100) and are much more stable in the environment than enteric bacteria, usually used as fecal contamination indicators (for example Escherichia coli, or Salmonella spp.) (Noble, Lee, & Schiff, 2004). ...
... Sustainable development goals (SDGs; 2015-2030), constitute an extension of millennium development goals (MDGs;2000, and were adopted by all United Nations Member States as universal call to action for poverty eradication, global prosperity, and environment protection (Sachs, 2012;World Health Organization., 2015). ...
The production of minimally processed foods is a critical process as the organoleptic characteristics of the food must be maintained. However, the treatments applied to this type of food may not be enough to eliminate the pre and postharvest foodborne microbiological contamination that can occur during the irrigation, fertilization, as well as the handling up to delivery and final consumption. In addition to bacterial and parasitic foodborne pathogens, enteric viruses pose health risks to consumers as they can be resistant to many of the standard procedures in the elaboration of minimally processed foods, while remaining stable at room temperature and refrigeration, as well as in raw or lightly cooked products (for example, bivalve molluscs). This chapter reviews human and zoonotic viral contamination in minimally processed foods and the current strategies for their control.
... This behavior pattern is accepted widely around the world (Dagevos & Voordouw, 2013). It is expected that by 2030 the demand for food of animal origin will be more than 50% compared to 2000(van Wagenberg et al., 2017 and according to Derner et al. (2017) the animal production should increase by 70% by 2050 to satisfy consumers' demands for meat and muscle products. This increase in demands requires the changes in the current livestock production patterns, which should be able to avoid extra pressure on the ecosystem, and aim for the "sustainability." ...
... Enteric viruses have fecal-oral route and are excreted in diarrheic feces in large concentrations (up to 10 11 viral particles per g) (Gerba, 2000). They have low infective doses (1-100) and are much more stable in the environment than enteric bacteria, usually used as fecal contamination indicators (for example Escherichia coli, or Salmonella spp.) (Noble, Lee, & Schiff, 2004). ...
... Sustainable development goals (SDGs; 2015-2030), constitute an extension of millennium development goals (MDGs;2000, and were adopted by all United Nations Member States as universal call to action for poverty eradication, global prosperity, and environment protection (Sachs, 2012;World Health Organization., 2015). ...
In the last decades, the interest in new food products with improved functional properties that promote health benefits is growing. Agri-food by-products constitute an excellent bio-resource to obtain new prebiotics and functional oligosaccharides. Particularly, pectin-rich agricultural by-products are potential cost-effective sources of functional pectooligosaccharides (POS) that have been outlined in recent years as emerging prebiotics with numerous health-promoting effects. An important aspect that influences the functionalities of the POS is the extraction methods. In this sense, a variety of alternative methods have been described to obtain POS using different sources including conventional and emerging intensification technologies. Several biological activities of POS such as prebiotic, antidiabetic, anticholesterolemic, antiobesity, antitumor, antioxidant, antiinflamatory, and antimicrobial, among other, have been described. Therefore, POS could be excellent candidates to formulate functional food by the nutraceutical industry. This chapter collects the aforementioned aspects to give an overview of the potential of POS as functional compounds obtained from renewable resources.
... This assumed that most of the variation is due to differences in bacterial concentration in fecal matter among individuals, with the rest coming from variations in the rate of fecal matter release. An alternative estimate is available in the model using 15-minute shower graywater data for the quantity of fecal coliforms divided by their concentration [47]. These rates are shown in Table 2. ...
... Age Group Low Mean High [46] All a 0.04 0.70 3.5 [47] Children b 0.67 21.1 c 667 [47] Adult 0.0067 0.21 c 6.67 a Values for 25 adults aged 20-84 in indoor pool C. Similar results were seen in the referenced study for the only child (10 years old) in outdoor pool D. b Families with small children 18 months to 9 years of age. c Geometric mean of the low and high rates. ...
... Age Group Low Mean High [46] All a 0.04 0.70 3.5 [47] Children b 0.67 21.1 c 667 [47] Adult 0.0067 0.21 c 6.67 a Values for 25 adults aged 20-84 in indoor pool C. Similar results were seen in the referenced study for the only child (10 years old) in outdoor pool D. b Families with small children 18 months to 9 years of age. c Geometric mean of the low and high rates. ...
Current regulatory codes for swimming pool disinfection separately regulate free chlorine (FC) and cyanuric acid (CYA). It is well-known that CYA affects disinfection rates by reversibly binding to FC in aqueous solutions. However, limits for these regulated parameters have neither systematically accounted for this chemistry nor been based on the risk of gastrointestinal illness. This study was intended to determine the minimum concentration of FC relative to CYA based on the risk of gastrointestinal illness from normal fecal sloughing of selected pathogens and to find a simple regulatory rule for jointly managing FC and CYA for consistent disinfection. Literature data on CYA’s effect on microbial inactivation rates were reanalyzed based on the equilibria governing hypochlorous acid (HOCl) concentration. A model was developed that considers the rates of pathogen introduction into pool water, disinfection, turbulent diffusive transport, and pathogen uptake by swimmers to calculate the associated risk of illness. Model results were compared to U.S. Environmental Protection Agency (EPA) untreated recreational water acceptable gastrointestinal illness risk. For Cryptosporidium, correlation between log inactivation and Chick–Watson Ct was far better when C refers to HOCl concentration than to FC (r = −0.96 vs. −0.06). The HOCl concentration had a small variation (± 1.8%) at a constant CYA/FC ratio for typical FC and CYA ranges in swimming pools. In 27 U.S. states, the allowed FC and CYA results in HOCl concentrations spanning more than a factor of 500. Using conservative values for a high bather load pool with 2 mg/L FC and 90 mg/L CYA, the model predicted a 0.071 annual probability of infection for Giardia, exceeding the EPA regulatory 0.036 limit for untreated recreational waters. FC and CYA concentrations in swimming pools should be jointly regulated as a ratio. We recommend a maximum CYA/FC ratio of 20.
... C&G are: resistant to chlorine, extremely small, require advanced filtration, present in high numbers, survive long periods in water, highly infectious at low doses and pose serious health consequences for immune-compromised individuals. Gerba (2000) describes the relationship between number of recreational visitors and percentage that shed enteric protozoans. Furthermore, on immersion, faecal shedding occurs with the release of faecal material with maximum shedding in the first 15 to 30 minutes. ...
... Furthermore, on immersion, faecal shedding occurs with the release of faecal material with maximum shedding in the first 15 to 30 minutes. Once faecal material is shed, Gerba (2000) found that the number of protozoan parasites ranged between 10 4 and 10 8 oocysts. Thus, C&G released in faeces are easily transmitted by humans through faecal shedding or alternatively by accidental faecal release (AFR). ...
... The numeric model was developed and configured to quantify and link recreation activity, faecal shedding of oocysts, sedimentation and surface mixing in a reservoir. The model was based on the approach of Gerba (2000) and extended to simulate the daily variation of Cryptosporidium oocysts based on: recreation visitor numbers, faecal shedding rate, dilution and sedimentation of oocysts within the reservoir. The model was enhanced to include mixing of oocysts within the surface layer during the summer (October through to June) when Logue Brook Dam is stratified. ...
Microbiological contamination of drinking water poses the greatest risk to public health. Recent studies show a strong link between recreation and contamination with the human infectious Cryptosporidium hominis. Furthermore, where recreation is allowed on a drinking water reservoir, the increased pathogen challenge is estimated to necessitate a 100-fold increase in the cost of treatment. The recent Parliamentary Inquiry in WA
attracted considerable interest across Australia. The report endorsed the need to protect water sources, but also recognised societal benefits of recreation. The report also recommended increased protection of key strategic catchments and increased penalties for infringement. An Interagency Working Group is now formed and tasked with implementing the recommendations. This paper shows there is an optimal balance
between allowing recreation activity in a drinking water catchment and still maintaining natural processes that provide safe drinking water at an affordable cost.
... Various studies have shown that bathers contribute to contamination of water, namely with Staphylococcus aureus, enteric viruses, protozoan parasites, IE, and fecal coliforms (Breittmayer and Gautier, 1978;Gerba, 2000;Elmir et al., 2007). In particular, it has been shown that bathers may develop enteric infections from contamination with stools of other bathers (Keene et al., 1994). ...
... Indeed, during this study, we observed parents encouraging children under 5 to urinate and defecate in the water, and others collected baby diapers after wringing them out in seawater. Gerba (2000) showed in a review of the literature that bathers of all ages shed enteric microorganisms through normal recreational water contact or accidental fecal release. In our study of the Prophète beach, the same issues were highlighted. ...
A highly frequented beach in Marseille, France, was monitored on an hourly basis during a summer day in July 2018, to determine possible water and sand fecal pollution, in parallel with influx of beach users from 8 a.m. to 8 p.m. Fecal indicator bacteria were enumerated, together with four host-associated fecal molecular markers selected to discriminate human, dog, horse, or gull/seagull origins of the contamination. The antimicrobial resistance of bacteria in water and sand was evaluated by quantifying (i) the class 1, 2, and 3 integron integrase genes intI , and (ii) bla TEM , bla CTX–M , and bla SHV genes encoding endemic beta-lactamase enzymes. The number of beach users entering and leaving per hour during the observation period was manually counted. Photographs of the beach and the bathing area were taken every hour and used to count the number of persons in the water and on the sand, using a photo-interpretation method. The number of beach users increased from early morning to a peak by mid-afternoon, totaling more than 1,800, a very large number of users for such a small beach (less than 1 ha). An increase in fecal contamination in the water corresponded to the increase in beach attendance and number of bathers, with maximum numbers observed in the mid-afternoon. The human-specific fecal molecular marker HF183 indicated the contamination was of human origin. In the water, the load of Intl 2 and 3 genes was lower than Intl 1 but these genes were detected only during peak attendance and highest fecal contamination. The dynamics of the genes encoding B-lactamases involved in B-lactams resistance notably was linked to beach attendance and human fecal contamination. Fecal indicator bacteria, integron integrase genes intI , and genes encoding B-lactamases were detected in the sand. This study shows that bathers and beach users can be significant contributors to contamination of seawater and beach sand with bacteria of fecal origin and with bacteria carrying integron-integrase genes and beta lactamase encoding genes. High influx of users to beaches is a significant factor to be considered in order to reduce contamination and manage public health risk.
... The list of viruses, which is summarized in Table 1, is very long (Fabiszewski de Aceituno et al., 2013) and includes viruses primarily transmitted via food or drinking water, such as enteroviruses, hepatitis A virus, hepatitis E virus, norovirus, and rotavirus (Vasickova et al., 2005;Bosch et al., 2018;Velebit et al., 2019). Humans infected with these viruses often shed large amounts of virus particles in the diarrheal feces (~10 5 to >10 12 infectious particles per ml or g) (Gerba, 2000;Bishop, 1996) while the infective dose is relatively low (~10 1 to 10 2 infectious particles) which easily leads to infection upon ingestion of the contaminated food (Anderson and Weber, 2004;Todd et al., 2008). The Table 1 list also includes some emerging zoonotic viruses capable of being transmitted via food (Koopmans and Duizer, 2004), such as SARS-CoV, Nipah virus (Luby et al., 2006), and highly pathogenic avian influenza (HPAI) virus (FAO/WHO Food and Agriculture Organization of the United Nations/World Health Organization, 2008) that can replicate in the human gastrointestinal tract and have animal reservoirs and are therefore a permanent threat for pandemics (Bosch et al., 2018). ...
... The more virus consumed in a food, the more likely an illness will result (Todd et al., 2008). Foodborne virus infections often result in shedding large amounts of virus particles in the diarrheal feces or vomitus (~10 5 to >10 12 infectious particles per ml or g) (Gerba, 2000;Bishop, 1996) that easily lead to infection upon ingestion of the contaminated food (Anderson and Weber, 2004;Todd et al., 2008). Since viruses do not replicate in non-living cells, the amount of infectious SARS-CoV-2 transferred this way would have to be massive to be sufficient to infect. ...
Outbreaks of COVID-19 (coronavirus disease 2019) have been reported in workers in fish farms and fish processing plants arising from person-to-person transmission, raising concerns about aquatic animal food products' safety. A better understanding of such incidents is important for the aquaculture industry's sustainability, particularly with the global trade in fresh and frozen aquatic animal food products where contaminating virus could survive for some time. Despite a plethora of COVID-19-related scientific publications, there is a lack of reports on the risk of contact with aquatic food animal species or their products. This review aimed to examine the potential for Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) contamination and the potential transmission via aquatic food animals or their products and wastewater effluents. The extracellular viability of SARS-CoV-2 and how the virus is spread are reviewed, supporting the understanding that contaminated cold-chain food sources may introduce SAR-CoV-2 via food imports although the virus is unlikely to infect humans through consumption of aquatic food animals or their products or drinking water; i.e., SARS-CoV-2 is not a foodborne virus and should not be managed as such but instead through strong, multifaceted public health interventions including physical distancing, rapid contact tracing, and testing, enhanced hand and respiratory hygiene, frequent disinfection of high-touch surfaces, isolation of infected workers and their contacts, as well as enhanced screening protocols for international seafood trade.
... Un baigneur apporte environ 35 millions de micro-organismes par l'intermédiaire de la peau, des muqueuses, des sécrétions rhinopharyngées des matières fécales, etc. (Spinasse, 2000). La quantité moyenne de selles émise par baigneur, en l'absence de tout incident de défécation, a été estimée à 140 mg, les enfants rejetant entre 10 mg et 10 g, les adultes entre 0,1 et 100 mg (Gerba, 2000). Les baigneurs rejettent des quantités importantes de germes pendant les 15 premières minutes d'immersion (Elmir et al., 2007). ...
... L'excrétion fécale par l'homme est estimée à 10 11 particules virales par gramme de selle (Gerba, 2000). ...
... Viral contamination of aquatic environments represents a major public health concern, because these environments can become major routes of exposure to pathogens associated with outbreaks of acute gastrointestinal illnesses in humans, by the inadvertent ingestion of contaminated water during recreational activities (Koh et al. 2011;Vergara et al. 2016;Kauppinen et al. 2017). In addition, bathers may release a significant concentration of enteric viruses into the water through the release of feces during body contact recreation (Gerba, 2000). ...
... Water quality variables outlined in the regulations for Mexico (NOM-127-SSA1-1994:2000 include total coliforms and E. coli. However, bacterial indicators provide little to no information about other human pathogens that might be present, including viruses, which can lead to minimizing the potential for identification of additional health risks (Lee et al. 2013). ...
Aims:
To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico.
Methods and results:
Hollow fiber ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real time quantitative polymerase chain reaction (qPCR) assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml, respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1,600 genome copies per liter (GC l-1 ). The NoV genogroup II (GII) was detected in 30% and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16, and GII.P17, and HAdV F serotypes 40 and 41.
Conclusions:
These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico.
Significance and impact of study:
This is one of few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations, and diversity of NoVs and HadVs in these particular environments. This article is protected by copyright. All rights reserved.
... Tais células são responsáveis pela absorção de água entre outros nutrientes, logo, a replicação viral nessas células acarreta liberação de partículas virais nas fezes em altas quantidades (Todd et al., 2008;Nyenje & Ndip, 2013;Orenstein, 2020). Estima-se que pacientes infectados por protozoários, por exemplo, apresentam em torno de 10 6 -10 7 (Giardia e Cryptosporidium) cistos/oocistos por grama de fezes, por outro lado, vírus como Rotavírus e Vírus da Hepatite A são excretados em torno de 10 8 -10 12 partículas virais por grama de fezes (Gerba, 2000) pelos infectados, podendo contaminar o ambiente onde estes dejetos são direcionados. Além dos vírus entéricos, outros patógenos virais podem ser excretados pelas fezes de pacientes e animais contaminados, como observado por pacientes infectados por SARS-CoV-2. ...
... [2019] and Sprenger et al. [2011]. Reduced human activities further decrease bacterial loads in water [Gerba, 2000]. Conversely, summer conditions, characterized by higher temperatures, lower river flows, and increased human activities, elevate WQI, corroborating the studies by Brock ...
... Probabilistic methods were developed for quantifying the fecal pollution of water resources (Arnone and Walling, 2006;Gerba, 2000;Sanders et al., 2013). Dorner et al. (2004) used a probabilistic approach for quantifying the daily produced numbers of Campylobacter and Cryptosporidium based on the animal fecal shedding rates and pathogen source concentrations for the same study area as in Lee et al. (2014). ...
... Incluso ocurren liberaciones fecales accidentales, con una frecuencia de una por cada 1,000 personas, lo que tiene un impacto significativo en la concentración de patógenos en el agua. 3,4 Los brotes asociados con agua tratada para fines recreativos o terapéuticos pueden ser causados ya sea por patógenos o productos químicos de piscinas, jacuzzis u otras estructuras construidas artificialmente. Entre 155 (75%) brotes con una etiología infecciosa confirmada, 76 (49%) fueron causados por Cryptosporidium y 65 (42%) por Legionella. ...
Viruses, bacteria, parasites and fungi can be contracted in
swimming pool water, and if not properly controlled, coupled with
humidity and heat, represent a breeding ground for a variety of
infections. Enteric pathogens can be added to recreational waters
by bathers, either by direct fecal route or from skin surfaces
or bathing suits during contact with the water. People with
gastroenteritis may be unable to control their bowel movements
and may release anything from a moderate amount to excrement
on bathing clothes. When swallowing these waters, various
pathogens can be acquired, among which are: hepatitis A or
E, Escherichia coli, certain parasites, fungi, such as Candida
albicans, which can affect the skin, mouth or genital organs, are
spread by contact, as well as fungi that affect the soles of the
feet (Tinea).
... While person-to-person and surface-to-person transmission can occur, viruses in wastewater that contaminate drinking water sources, recreational waters, and shellfish harvesting waters pose the greatest risk to the public. (Baker-Austin et al., 2018;Gerba, 2000) Furthermore, seroprevalence studies for hepatitis A among windsurfers, waterskiers, and canoeists who were exposed to contaminated waters have not identified any increased health risks. One of the primary concerns of public health officials is the relationship between the presence of pathogens and the recreational risk to human health in polluted marine environments. ...
... Adenovirüsler tüm dünyada ham kanalizasyonda tespit edilmiştir ve bu virüs bir dizi insan hastalığı ile ilişkilidir, ancak oluşumları ve patojeniteleri tam olarak araştırılmamıştır. (Jiang, 2006;Mena & Gerba, 2009 (Gerba, 2000;Vantarakis & Papapetropoulou, 1998 ...
... Enteric viruses are also frequently detected in wastewater. Enteric pathogenic viruses are shed in high concentrations (10 5 -10 12 viral particles per gram of fecal matter) (Gerba, 2000) and tend to have low infectious doses (e.g., rotavirus and norovirus can be infectious at doses of 10-100 virus particles) (Yezli and Otter, 2011;Santiago-Rodriguez, 2022). Wastewater surveillance, as part of the "Global Polio Eradication Initiative," was implemented in multiple countries to monitor poliovirus in the population before 2000 (Hovi et al., 2012). ...
Domestic wastewater, when collected and evaluated appropriately, can provide valuable health-related information for a community. As a relatively unbiased and non-invasive approach, wastewater surveillance may complement current practices towards mitigating risks and protecting population health. Spurred by the COVID-19 pandemic, wastewater programs are now widely implemented to monitor viral infection trends in sewersheds and inform public health decision-making. This review summarizes recent developments in wastewater-based epidemiology for detecting and monitoring communicable infectious diseases, dissemination of antimicrobial resistance, and illicit drug consumption. Wastewater surveillance, a quickly advancing Frontier in environmental science, is becoming a new tool to enhance public health, improve disease prevention, and respond to future epidemics and pandemics.
... Human pathogens such as Cryptosporidium can contaminate the water supply through either direct human contact or human waste that is disposed of inappropriately, and public access is a well-known source of pathogens in water storages and catchments (Billington andDeere 2020, Miller et al. 2006). This is particularly true for full body-contact activities in reservoirs (Loganthan et al. 2012); a single infectious person can unknowingly release millions of microbial organisms, such as protozoa and enteric viruses, into waterbodies (Gerba 2000). Recreational activities can also introduce chemicals and nutrients, increase sediment loads, and change the ecology of, and natural processes in, water sources (Miller et al. 2006), as well as adversely affecting the surrounding environment through increasing fire risk, damaging ecosystems and species distribution, and introducing pest species and disease (Krogh et al. 2009). ...
While natural and anthropogenic hazards are increasing, Disaster Risk Reduction (DRR) can protect individuals and communities from the adverse effects of disasters associated with those hazards. DRR can be achieved through implementing policies to reduce or remove hazards; such policies, however, are often restrictive and, therefore, contravene personal desires and freedoms. As policies need to be accepted and followed by the community to be effective, it is important to understand the variables influencing community acceptance of those policies. A literature review revealed there was no accepted model of policy support, but that risk perception was likely to be a key influencing factor. A candidate model — the Health Belief Model (HBM) — was identified in the health behaviour field, and tested in the novel context of policy support for its ability to explain support for policies restricting recreational activities in drinking water catchments, which are implemented by metropolitan water managers in Australia to reduce contamination risks to potable water sources. Through Partial Least Squares Structural Equation Modelling, the HBM was found to have good explanatory power for recreation policy support in a sample of the adult population of the lower Hunter Region of New South Wales. Modelling and subsequent analyses determined that risk perception was a key driver of policy support in the sample, and that other important influencing variables in this context included gender and self-interest, particularly in the form of proximity of residence to catchments and personal recreation preferences. The influence of self-interest has important implications for community engagement activities. The HBM can identify factors to which information and education campaigns can be targeted in order to increase community acceptance of risk reduction policies, and has potential application as a general model of risk reduction policy support, particularly in the health and disaster domains. Use of the HBM may assist in the mitigation of disaster risk by helping to increase community acceptance of disaster risk reduction policies.
... Probabilistic methods were developed for quantifying the fecal pollution of water resources (Arnone and Walling, 2006;Gerba, 2000;Sanders et al., 2013). Dorner et al. (2004) used a probabilistic approach for quantifying the daily produced numbers of Campylobacter and Cryptosporidium based on the animal fecal shedding rates and pathogen source concentrations for the same study area as in Lee et al. (2014). ...
We developed an innovative approach to estimate the extent of fecal pollution sources for urban river catchments. The methodology consists of 1) catchment surveys complemented by literature data where needed for probabilistic estimates of daily produced fecal indicator (FIBs, E. coli, enterococci) and zoonotic reference pathogen numbers (Campylobacter, Cryptosporidium and Giardia) excreted by human and animal sources in a river catchment, 2) generating a hypothesis about the dominant sources of fecal pollution and selecting a source targeted monitoring design, and 3) verifying the results by comparing measured concentrations of chemical tracers, C. perfringens, and host-associated genetic microbial source tracking (MST) markers in the river, and by multi-parametric correlation analysis. We tested the approach at a study area in Vienna, Austria. The daily produced microbial particle numbers according to the probabilistic estimates indicated that, for the dry weather scenario, the discharge of treated wastewater (WWTP) was the primary contributor to fecal pollution. For the wet weather scenario, 80-99 % of the daily produced FIBs and pathogens resulted from combined sewer overflows (CSOs) according to the probabilistic estimates. When testing our hypothesis in the river, the measured concentrations of the human genetic fecal marker were log10 4 higher than for selected animal genetic fecal markers. Our analyses showed for the first-time statistical relationships between C. perfringens and a human genetic fecal marker (i.e. HF183/BacR287) with the reference pathogen Giardia in river water (Spearman rank correlation: 0.78-0.83, p < 0.05. The developed approach facilitates urban water safety management and provides a robust basis for microbial fate and transport models and microbial infection risk assessment.
... Also, higher water temperatures are known to stimulate growth of some pathogenic bacterial species (Baker-Austin et al., 2013;Charron et al., 2004;Hunter, 2003). Moreover, in urban areas, water can be easily contaminated with pathogens by humans and pets during recreational activity (Elmir et al., 2007;Gerba, 2000;Plano et al., 2011), wildlife (Babudieri, 1958;Markwell and Shortridge, 1982), storm water runoff (Kupek et al., 2000;Schillinger and Gannon, 1985;Ward, 2002), agriculture (Givens et al., 2016;Walters et al., 2011) and wastewater effluents (Cai and Zhang, 2013;Numberger et al., 2019a;Steyer et al., 2015). Although there are hints that lake trophy and anthropogenic activity drive microbial community composition and function (Kiersztyn et al., 2019), it remains unclear which specific bacterial groups are indicative for increasing urbanization and hence may serve as indicators for environmental and human health risks. ...
Freshwater ecosystems are characterized by complex and highly dynamic microbial communities that are strongly structured by their local environment and biota. Accelerating urbanization and growing city populations detrimentally alter freshwater environments. To determine differences in freshwater microbial communities associated with urbanization, full-length 16S rRNA gene PacBio sequencing was performed in a case study from surface waters and sediments from a wastewater treatment plant, urban and rural lakes in the Berlin-Brandenburg region, Northeast Germany. Water samples exhibited highly habitat specific bacterial communities with multiple genera showing clear urban signatures. We identified potentially harmful bacterial groups associated with environmental parameters specific to urban habitats such as Alistipes, Escherichia/Shigella, Rickettsia and Streptococcus. We demonstrate that urbanization alters natural microbial communities in lakes and, via simultaneous warming and eutrophication and creates favourable conditions that promote specific bacterial genera including potential pathogens. Our findings are evidence to suggest an increased potential for long-term health risk in urbanized waterbodies, at a time of rapidly expanding global urbanization. The results highlight the urgency for undertaking mitigation measures such as targeted lake restoration projects and sustainable water management efforts.
... Their replication occurs within the gastrointestinal tract of their hosts, leading to large numbers of viruses excreted together with the faeces, up to 10 12 particles. g − 1 of faeces, then entering wastewaters (Gerba, 2000;Blacklow and Greenberg, 1991). ...
Enteric viruses are widely spread in water environments, some being harmful for human communities. Regular epidemics highlight the usefulness of analysing such viruses in wastewaters as a tool for epidemiologists to monitor the extent of their dissemination among populations. In this context, CNovel™ Powdered Activated Carbon (PAC) was chosen for its high porosity and high adsorption capacity to investigate sorbent ability to be used as part of of virus detection probes. Self-supported PAC Foils (PAC-F), PAC coated Brushes (PAC-B) and PAC Sampler (PAC-S) were used to prospect PAC efficacy in virus adsorption and above all, the feasibility of virus retrieval from them, allowing to further analysis such as molecular analysis quantification. Aiming at the development of a field-operational tool, PAC saturation and reusability were also investigated, as well as PAC-polarisation effect on its adsorption capacity.
Our results pointed out that sorbent-based probes exhibited a high adsorption efficacy of spiked Murine Norovirus (MNV-1) in bare 0.1 M NaCl solution (>90 % for PAC-B and >86 % for PAC-F at ≈10⁷ genome unit virus concentration), with no saturation within our experimental framework. On the other hand, polarisation assays using PAC-F as electrode, did not demonstrate any adsorption improvement. Experiments on PAC probes reusability suggested that they should be used three times at the most for a maximum efficiency. Values of virus retrieval were low (up to 11 % with PAC-B and up to 14 % with PAC-F in 0.1 M NaCl virus suspensions), illustrating the need for the techniques to be improved. A preliminary field assay using PAC-S, demonstrated that our catch-and-retrieve protocol yielded to the detection of autochthonous human Norovirus Genogroup I (NoV GI) and Adenovirus (AdV), in wastewaters suggesting its promising application as virus detection tool in such high loaded and complex waters.
... Most previous reviews of recreation in freshwater ecosystems did not focus on one specific activity (Table 1) but concentrated on disturbance in general (Blumstein et al., 2005;Cayford, 1993;Price, 2008) or on recreational use in general (Blanc et al., 2006;Carney & Sydeman, 1999;Cole & Landres, 1996). In a more specific approach, Gerba (2000) reviewed the shedding of enteric pathogens during recreational swimming, without, however, linking the amount of material shed by bathers to the effect on aquatic organisms. We are not aware of reviews on the ecological effects of swimming, snorkelling, scuba diving, canyoning, walking, biking or relaxing close to an inland water body. ...
With the increasing importance of recreational activities in and around inland water bodies, there is a need for sound knowledge about their ecological impacts. This narrative review summarizes and analyses the ecological effects of the land-based activities walking, biking, nature observing and relaxing on the shoreline as well as the water-based activities swimming, snorkelling, scuba diving, and canyoning. Searching multiple databases with standardized search terms retrieved twenty-six publications for further analyses. While walking was the most studied activity, birds were the most studied organism group, with a focus on individual time budgets and avoidance behaviour. Population-level analyses were exceedingly rare. The most frequently studied activity-effect combinations were walking and birds, walking and terrestrial plants and scuba diving/snorkelling and fishes. Aquatic plants, amphibians, reptiles, water chemical parameters and terrestrial and aquatic algae were underrepresented in the existing literature. No study on mammals was identified. Disturbance often led to temporary behavioural changes of birds and wildlife. Plants were more strongly impacted than animals, suffering from recreation-induced damage and dieback, which led to changes in community composition. The difference in intensity of impact between mobile and sessile organisms calls for different management strategies, depending on local conservation targets. Future studies should focus on underrepresented taxonomic groups and study population or community-level impacts, to collectively provide the sound scientific basis for the sustainable recreational use of inland water bodies, while minimizing or avoiding severe ecological impacts.
... 37 Since the final viral concentration depends on the time from source to collection, the pipeline structure for each individual treatment plant is a key factor; however, viral particle concentrations in wastewater are typically 10 5 to 10 15 per gram of fecal matter. 33,41 The main limitations of WBE as an early warning system are the inability to (1) estimate the true population size, (2) register fluctuations over short time spans, and (3) provide a detailed spatial distribution within the region. This approach is not appropriate for direct contact tracing but can be useful at the community level. ...
... On the other hand, some pathogens may increase in concentration via regrowth capabilities, particularly in moist or humid storage conditions and laundry heavily contaminated with bodily fluids. Here, we evaluate microbial hazards in laundry representative of a nonenveloped respiratory virus (rhinovirus), a nonenveloped enteric virus (rotavirus) and a Gram-negative bacterium (nontyphoidal Salmonella) and estimate from the literature initial concentrations of 10 7 , 10 11 and 10 10 respectively (Table 3) (Gerba, 2000;L'Huillier et al., 2015). Die-off during storage alone may be greater than 4 logs for unwashed laundry contaminated with enveloped or respiratory viruses (Gerhardts et al., 2016;Harbourt et al., 2020;Sakaguchi et al., 2010). ...
Aims:
Contaminated laundry can spread infections. However, current directives for safe laundering are limited to healthcare settings and not reflective of domestic conditions. We aimed to use quantitative microbial risk assessment to evaluate household laundering practices (e.g., detergent selection, washing and drying temperatures, and sanitizer use) relative to log10 reductions in pathogens and infection risks during the clothes sorting, washer/dryer loading, folding, and storing steps.
Methods and results:
Using published data, we characterized laundry infection risks for respiratory and enteric pathogens relative to a single user contact scenario and a 1.0 x 10-6 acceptable risk threshold. For respiratory pathogens, risks following cold water wash temperatures (e.g., median 14.4°C) and standard detergents ranged from 2.2 x 10-5 to 2.2 x 10-7 . Use of advanced, enzymatic detergents reduced risks to 8.6 x 10-8 and 2.2 x 10-11 , respectively. For enteric pathogens, however, hot water, advanced detergents, sanitizing agents, and drying are needed to reach risk targets.
Significance and impact of study:
Conclusions provide guidance for household laundry practices to achieve targeted risk reductions, given a single user contact scenario. A key finding was that hand hygiene implemented at critical control points in the laundering process was the most significant driver of infection prevention, additionally reducing infection risks by up to six log10 .
... The major source of viruses in wastewater is fecal excretion to the water specifically from the infected individuals. According to an estimate, a single infected individual excretes approximately 10 5 -10 12 viral particles per gram of fecal excretion (Gerba, 2000). Likewise, another study reported that viruses are released into wastewater by more than 10 12 viruses g − 1 of feces from the infected individuals (Drexler et al., 2011;Kirby et al., 2014). ...
Millions of human pathogenic viral particles are shed from infected individuals and introduce into wastewater, subsequently causing waterborne diseases worldwide. These viruses can be transmitted from wastewater to human beings via direct contact and/or ingestion/inhalation of aerosols. Even the advanced wastewater treatment technologies are unable to remove pathogenic viruses from wastewater completely, posing a serious health risk. Recently, coronavirus disease 2019 (COVID-19) has been urged globally due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which has resulted in >4.1 million deaths until July 2021. A rapid human-to-human transmission, uncertainties in effective vaccines, non-specific medical treatments, and unclear symptoms compelled the world into complete lockdown, social distancing, air-travel suspension, and closure of educational institutions, subsequently damaging the global economy and trade. Although, few medical treatments, rapid detection tools, and vaccines have been developed so far to curb the spread of COVID-19; however, several uncertainties exist in their applicability. Further, the acceptance of vaccines among communities is lower owing to the fear of side effects such as blood-clotting and heart inflammation. SARS-CoV-2, an etiologic agent of COVID-19, has frequently been detected in wastewater, depicting a potential transmission risk to healthy individuals. Contrarily, the occurrence of SARS-CoV-2 in wastewater can be used as an early outbreak detection tool via water-based epidemiology. Therefore, the spread of SARS-CoV-2 through fecal-oral pathway can be reduced and any possible outbreak can be evaded by proper wastewater surveillance. In this review, wastewater recycling complications, potential health risks of COVID-19 emergence, and current epidemiological measures to control COVID-19 spread have been discussed. Moreover, the viability of SARS-CoV-2 in various environments and survival in wastewater has been reviewed. Additionally, the necessary actions (vaccination, face mask, social distancing, and hand sanitization) to limit the transmission of SARS-CoV-2 have been recommended. Therefore, wastewater surveillance can serve as a feasible, efficient, and reliable epidemiological measure to lessen the spread of COVID-19.
... Our results agreed with the prevalence of enteric viruses in different environmental waters in other study (Haramoto, et al, 2018). The mean levels of enteric viruses in infected individuals could range from 10 5 to 10 12 genomic copies of virus per gram of faeces (Gerba, 2000). The estimated levels of the viruses detected by qPCR in groundwater from private wells in rural Alberta would be equivalent to 1.5×10 − 5 to 8.6×10 − 11 gram of faecal contamination in one liter of contaminated water using this calculation. ...
The prevalence and levels of enteric viruses in untreated groundwater of private wells used for drinking and/or agricultural practices in rural Alberta were studied using the qPCR panel assay, integrated cell culture with qPCR and cell culture in the volume of 500 liters per sample through serial sampling. Seven viruses were assessed including adenovirus, rotavirus, norovirus, astrovirus, sapovirus, reovirus and JC virus. Five viruses were detected with an overall positive detection rate of 6.33 % (45 of 711 samples). The most frequently detected virus was adenovirus (48.9%, 22/45) followed by rotavirus (44.4%, 20/45), reovirus (20%, 9/45), JC virus (6.7%, 3/45) and norovirus (6.7%, 3/45). There was no significant difference in the positive detection rates, ranging from 1.1% to 3.4% by various well settings used for broiler farms, cow/calf farms, feedlots and rural acreages. Effects of well characteristics (aquifer type, well depth, static level of water, well seal) and well completion lithology on potential viral contamination of groundwater of private wells were also analyzed upon available data. The findings demonstrate that occurrence of enteric viruses is low and viral contamination is sporadic in groundwater of private wells in rural Alberta. Conventional fecal bacterial indicators (coliform and/or E. coli) were not a representative marker for viral contamination in groundwater wells in rural Alberta.
... Pathogenic streptococci and other bacteria could be introduced into seawater by shipping traffic including ballast water [219,220], human activities including recreational activity [221][222][223][224][225] and waste (water) [66,[226][227][228][229] and from the terrestrial environment via rivers and storm water [230,231], wind transport [232,233] or animals, e.g., semi-aquatic mammals, such as pinnipeds, from which streptococci are frequently isolated. For instance, human pathogenic S. agalactiae strains were identified in grey seals indicating that sea mammals were exposed to human pathogens via human effluents that contaminate coastal surface waters [66]. ...
Marine mammals are sentinels for the marine ecosystem and threatened by numerous factors including infectious diseases. One of the most frequently isolated bacteria are beta-hemolytic streptococci. However, knowledge on ecology and epidemiology of streptococcal species in marine mammals is very limited. This review summarizes published reports on streptococcal species, which have been detected in marine mammals. Furthermore, we discuss streptococcal transmission between and adaptation to their marine mammalian hosts. We conclude that streptococci colonize and/or infect marine mammals very frequently, but in many cases, streptococci isolated from marine mammals have not been further identified. How these bacteria disseminate and adapt to their specific niches can only be speculated due to the lack of respective research. Considering the relevance of pathogenic streptococci for marine mammals as part of the marine ecosystem, it seems that they have been neglected and should receive scientific interest in the future.
... , Reg. 565, 2018United States Centers for Disease Control and Prevention, 2018). Showering prior to swimming is important because bathers have been estimated to shed an average of 0.14 g of fecal material when swimming, which can contain pathogens such as Cryptosporidium or Giardia (Gerba, 2000). In addition, the presence of organic material from bathers lowers the effectiveness of halogen-based disinfectants such as chlorine (Shields et al., 2008). ...
Bathers at public swimming pools should shower prior to entering the pool deck to remove organic material (e.g., sweat, lotions, fecal matter) that can increase the risk of recreational water illness and the formation of disinfection by-products. However, little research has been conducted to evaluate bathers’ pre-swimming showering practices. We conducted a cross-sectional study of bathers aged 18 years or older at a public swimming pool in Toronto, Ontario, to evaluate their showering habits. An in-person questionnaire was administered in October and November 2019. Bivariate associations were examined between selected variables and participants’ self-reported showering frequency prior to swimming (often or always vs. never, rarely, or sometimes). A total of 110 bathers agreed to participate. Most participants (63%) were aged 18–34, 56% identified as male, and 78.2% reported always or often showering before swimming. Of these individuals, only 34% reported using soap when showering. Participants that identified as male (vs. female) and an ethnicity other than white were more likely to report often or always showering, as were those that reported reading the pool rules and that observed other bathers taking a shower. Additional efforts are needed to educate bathers about the importance of showering prior to swimming in public pools.
... It is likely that bacterial shedding from the swimmers represents a primary source of the human-source fecal bacteria MST markers detected. Previous studies by others and ourselves have shown that bathers can shed large amounts of fecal and skinassociated bacteria, including Enterococcus, fecal Bacteroides, and Staphylococcus aureus among others (Gerba, 2000;Elmir et al., 2007Elmir et al., , 2009Plano et al., 2011). While there are undoubtedly some incidents of direct defecation into Grotto waters by certain individuals unwilling to hike back up the cliff to the only restroom facility, this human fecal marker signal is more likely attributable to unintentional routine bacterial shedding by general bathers. ...
The Commonwealth of the Northern Mariana Islands (CNMI) recently identified the need to improve its capacity for detecting and tracking land-based sources of pollution (LBSP) in coastal waters, particularly microbial contaminants like fecal indicator bacteria (FIB). Reported here is a baseline study of a suite of host-specific FIB microbial source tracking (MST) markers in the coastal shoreline and reef waters around the island of Saipan. Three sampling campaigns were conducted in September 2017, March 2018, and August 2018. Samples were collected from the nearshore surface waters of Saipan, the reef waters of Saipan Lagoon, and groundwater from beaches along the Saipan Lagoon shoreline. Measurements of submarine groundwater discharge (SGD) into nearshore waters and isotopic source tracking of nitrogen inputs were conducted concurrently with MST. Environmental DNA was extracted from the samples and analyzed by quantitative polymerase chain reaction (qPCR) for MST gene markers of fecal Bacteroidales specifically associated with humans, dogs, cows, and pigs, and for an MST gene marker of Catellicoccus associated with seabirds. MST assessments were combined with local knowledge, assessments of sanitary infrastructure, and routine watershed surveys. This study identified hotspots of human FIB along the western Saipan Lagoon shoreline in both surface waters and groundwater, plus another hotspot of human FIB at a popular tourist bathing area known as the Grotto. FIB hotspots on the Lagoon shoreline coincided with areas of high SGD and nitrogen isotopic data indicating sewage-derived N inputs. It appears that faulty sanitary infrastructure may be contributing to inputs to Saipan Lagoon, while bather shedding is likely a primary input for the Grotto area. Moderate levels of dog fecal contamination were common and widespread across the island. High levels of seabird fecal contamination were more random, both spatially and temporally, and mostly concentrated along the less developed northeast region of Saipan. No significant levels of cow or pig fecal marker were detected in coastal water samples. This study provides demonstration and establishment of analytical capacity to resource management in CNMI for MST technology to aid in trouble-shooting water quality issues involving land-based sources of microbial contaminants to CNMI coastal waters.
... Additionally, other pathogenic agents, like viruses, can also persist in raw wastewater and treated wastewater as well as in the receiving water bodies [11]. One of the main sources of viral pathogens in wastewater is the human fecal matter from infected persons [12][13][14] that can shed 10 5 to 10 12 viral particles per gram of fecal matter [15]. Besides human pathogenic viruses, waterborne viruses that originate from food production, animal husbandry, seasonal surface runoff and other sources are also present in wastewater [16]. ...
Broad-spectrum fluoroquinolone antibiotics (ciprofloxacin and levofloxacin), carbapenem and fluoroquinolone resistance genes, as well as viral genomes, were detected in grab samples of wastewater effluents. Passive samplers, which are simpler and easier to use and provide information about the concentrations and combination of contaminants present in a certain fluid matrix over time, proved to be extremely promising devices to monitor the presence of the target antibiotics in wastewater effluents. Nanofiltration was tested with a pilot-scale unit installed at a domestic wastewater treatment facility, using a Desal 5DK membrane operated at a constant transmembrane pressure of 6 bar and 70% recovery rate. In a 24 h experimental assay, the variation of the membrane permeance was low (6.3%). High rejections of the target contaminants from the wastewater effluent were obtained by the pilot-scale treatment. Hence, nanofiltration using the Desal 5DK membrane is considered to be a promising treatment to cope with chemical and biological contaminants present in wastewater effluents.
... Faecal shedding: Unintentional shedding of faecal material by bathers is widely documented (Elmir et al. 2009, Elmir et al. 2007, Gerba 2000. The amount of faeces shed per person is highly uncertain and was estimated relying on measurements from the literature of faecal indicator concentrations in bathing waters. ...
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.
... Contributions from landfills, septic tanks, cesspools, and cemeteries can leach through soil directly into groundwater seeping into the recreational water environment [209,210]. Swimmers and bathers in recreational waters might also serve as a source of AMR bacteria and ARGs as they can shed fecal material while recreating [211]. Published evidence linking these sources to AMR bacteria and ARGs in recreational water is not available. ...
Ambient recreational waters can act as both recipients and natural reservoirs for antimicrobial resistant (AMR) bacteria and antimicrobial resistant genes (ARGs), where they may persist and replicate. Contact with AMR bacteria and ARGs potentially puts recreators at risk, which can thus decrease their ability to fight infections. A variety of point and nonpoint sources, including contaminated wastewater effluents, runoff from animal feeding operations, and sewer overflow events, can contribute to environmental loading of AMR bacteria and ARGs. The overall goal of this article is to provide the state of the science related to recreational exposure and AMR, which has been an area of increasing interest. Specific objectives of the review include (1) a description of potential sources of antibiotics, AMR bacteria, and ARGs in recreational waters, as documented in the available literature; (2) a discussion of what is known about human recreational exposures to AMR bacteria and ARGs, using findings from health studies and exposure assessments; and (3) identification of knowledge gaps and future research needs. To better understand the dynamics related to AMR and associated recreational water risks, future research should focus on source contribution, fate and transport—across treatment and in the environment; human health risk assessment; and standardized methods.
... Sewage systems receive enteric viruses excreted by infected individuals. An infected person sheds 10 5 to 10 12 viral particles per gram of fecal matter (Gerba, 2000). In addition to human pathogenic viruses, waterborne viruses that originate from food production, animal husbandry, seasonal surface runoff and other sources are present in wastewater (Corsi et al., 2014). ...
This paper presents an updated and comprehensive review on the different methods used for detection and quantification of viruses in wastewater treatment systems. The analysis of viability of viruses in wastewater and sludge is another thrust of this review.
Recent studies have mostly focused on determining the abundance and diversity of viruses in wastewater influents, in samples from primary, secondary, and tertiary treatment stages, and in final effluents. A few studies have also examined the occurrence and diversity of viruses in raw and digested sludge samples. Recent efforts to improve efficiency of virus detection and quantification methods in the complex wastewater and sludge matrices are highlighted in this review.
A summary and a detailed comparison of the pre-treatment methods that have been utilized for wastewater and sludge samples are also presented. The role of metagenomics or sequencing analysis in monitoring wastewater systems to predict disease outbreaks, to conduct public health surveillance, to assess the efficiency of existing treatment systems in virus removal, and to re-evaluate current regulations regarding pathogenic viruses in wastewater is discussed in this paper. Challenges and future perspectives in the detection of viruses, including emerging and newly emerged viruses such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), in wastewater systems are discussed in this review.
... Therefore, inadequate adherence to sound disinfection protocols enhances risks for respiratory, ocular, and cutaneous ailments among pool visitors and workers (Fantuzzi et al., 2010;Nickmilder & Bernard, 2007). Furthermore, swimmer shedding of microbial flora (including potential pathogens) occurs in aquatic environments (Gerba, 2000;Smith & Dufour, 1993) and when coupled with insufficient disinfection, this situation presents an increased infectious disease risk to recreators. Studies on untreated recreational waters have demonstrated a positive association between densitites of fecal indicator organisms in water and the risk of experiencing a swimming-associated gas-A b s t r a c t The growth in the number of pools to more than 7.4 million in the U.S. has been accompanied by a rise in recreational water illnesses (RWIs). ...
The growth in the number of pools to more than 7.4
million in the U.S. has been accompanied by a rise in recreational water
illnesses (RWIs). Effective pool management, though, can mitigate RWI risks.
Inadequate management presumably occurs more frequently where training
is less formalized and/or pool operation is a minor aspect of the job of
the responsible pool manager(s). During summer 2018, weekly evaluations
were performed at public venues in Louisville, Kentucky. Disinfectant levels
and other items were monitored and compared with venue-specific (pool or
spa) criteria. Among 1,312 venue surveys, 1,173 (89.4%) met criteria and
139 (10.6%) did not meet criteria. Overall, multivariable logistic regression
showed a significant association between the likelihood of a venue meeting
criteria and setting type. Specifically, hotels had 120% increased odds of not
meeting criteria (adjusted odds ratio = 2.2; 95% confidence interval [1.3,
3.8]) compared with other settings. Despite spas having an 80% elevated
odds of not meeting criteria compared with pools in a univariate analysis,
upon adjusting for setting, spas were not associated with an increased risk
of not meeting criteria. Research identifying reasons for these differences in
meeting criteria between settings would be beneficial for informing public
health interventions for aquatic environments.
... 2005). Gerba (2000), günde birey başına 100 ila 200 g dışkı üretildiğinden, enfekte bir kişiden 100 g'lık bir tek bağırsak hareketinde 10 14 kadar enterik patojen hücresi yayılabileceğini belirlemiştir. Barker ve Jones (2005) patojenler dışkıda 10 4 ila 10 11 kob/g seviyesinde bulunabildiğinden, deriye 0.1 mg dışkı maddesi bulaşması halinde, diyarel koşullar altında 106'ya kadar enfeksiyöz bakteri hücresi, parazitik oositler veya viral partiküller içerebildiğini bildirmiştir. ...
Gıda ile ilgili işlemler sırasında el hijyeni kritik öneme sahiptir. Hasta veya iyileşmiş kişilerin dışkılarında patojenler bulunduğunda, kontaminasyon çoğunlukla fekal-oral yolla gerçekleşmektedir. Kontaminasyonun kökeni ne olursa olsun, patojenlerin çeşitli yüzeylere temas eden ellerden bulaşma olasılığı yüksektir. Gıda kontaminasyonunun risk faktörlerinden biri, gıda hizmetlerinde çalışanların kişisel hijyeninin yetersiz olmasıdır. Bu makale gıda işletmelerinde uygun el hijyeni ve eldiven kullanımı arasındaki ilişkinin halk sağlığı üzerindeki etkilerini değerlendirmek amacıyla hazırlanmıştır. Hand hygiene is critical importance during food-related processes. When pathogens are present in the feces of the patient or healed people, contamination is most often accomplished by the faecal-oral route. Regardless of the origin of contamination, pathogens are likely to be transmitted from hands that touch various surfaces. One of the risk factors of food contamination is the inadequate personal hygiene of those working in food services. This article has been prepared to evaluate the effects of the relationship between appropriate hand hygiene and glove use in food establishments on public health. Review
... Thus, the possibility of microbial contamination is high in coastal areas. (Gerba 2000;Alm et al. 2003). ...
The composition and metabolic properties of cultivable heterotrophic aerobic bacteria, the levels of indicator bacteria, and physicochemical parameters were investigated in the seawater samples collected from 20 stations in coastal areas of the eastern part of the Black Sea, Turkey, between May 2017 and February 2018. The levels of indicator bacteria were detected above the national limit values during the study period. Thirty-five different bacterium species were identified. Enterobacteriaceae was recorded as the most dominant family (34.2%), and Gammaproteobacteria was recorded as the most dominant class (74.2%). Bacteriological threats on human and ecosystem health were determined in coastal areas of the Southeastern Black Sea. The determination of the high levels of indicator bacteria, the high ratio of fecal coliform/fecal streptococci (FC/FS ratio), and pathogenic bacteria regarding human and ecosystem health showed that these coastal areas under the influences of terrestrial and human-sourced bacteriological pollution. This study has contributed to the increase of knowledge of understanding the protection and rehabilitation ways of the Black Sea coastal regions against land-based pollution sources considering the interdependent structure of all Black Sea countries. Coastal areas are accepted as the most fragile part of the marine environments and our findings showed the potential bacteriological risks in coastal areas of the Southeastern Black Sea as an important example. Serious precautions should be taken for the protection in this area and such coastal ecosystems to prevent hazardous problems.
... The DI value was calculated for a hypothetical scenario of inadvertent consumption of spinach leaves exposed to Ag 2 O and TiO 2 NPs or the corresponding Ag and Ti ions. The amount of spinach per serving, i.e., average daily intake of spinach for adults, were set as 0.345 kg/person/day and body weight for adult were set as 60 kg (Gerba, 2000). The concentration of metal in spinach, grown in sludge -mixed NPs were used to project DI of each metal by six age-mass classes from child to adult. ...
Present study carried out pot experiments and evaluated effects of single and binary mixture of nanoparticles (exposed via sludge as soil conditioner) on spinach plant. Exposure of Ag2O NPs (1 and 10 mg/kg) did not show and significant reduction in plant as compared to control. On the other hand TiO2 NPs (exposed as single and in binary mixture) resulted in significant increase in root length (29% and 37%) and fresh weight (60% and 48%) at highest exposure concentration. Total chlorophyll content decreased for Ag2O and binary mixture (7% and 4%) and increased for TiO2 (5%) at 10 mg/kg soil. The toxic interaction between Ag2O and TiO2 NPs was additive at both exposure concentrations. Ag2O NPs had higher tendency of root surface adsorption than TiO2 NPs. Metal content in spinach leaves at highest exposure concentration was Ag: 2.6 ± 0.55 mg/g (for Ag2O NPs) and 1.02 ± 0.32 mg/g plant biomass (for Ag2O + TiO2 NPs) and for Ti: 1.12 ± 0.78 (for TiO2 NPs) mg/g and 0.58 ± 0.41 mg/g (for Ag2O + TiO2 NPs). The inadvertent ingestion of NPs contaminated spinach resulted in projected daily intake (DI) of Ag and Ti for different age-mass classes (child to adult) exceeding the oral reference dose for toxicity during oral ingestion. In conclusion, we report no acute toxicity of single and binary mixture of NPs to spinach but significant accumulation of Ag and Ti metal in spinach leaves. There are high chances that ingestion of spinach grown in such environment might lead to human health risks.
... Rotavirus shedding rates from infected individuals can be as high as 10 12 rotavirus particles/g of faeces (Gerba, 2000;Guardabassi et al., 2003;Christensen, 1995;Walter, 2000;Charles et al., 2003), and virus shedding can continue for up to 30 days (Guardabassi et al., 2003). Thus, when a member of a household with an OWTS is infected with rotavirus, the rotavirus concentrations in the septic tank effluent can be extremely high d up to 8 Â 10 10 rotavirus particles/L during the peak shedding period and 10 6 rotavirus particles/L 30 days after the peak period (Charles et al., 2003). ...
Contamination of potable groundwater by pathogenic viruses from on-site wastewater treatment systems (OWTS) poses a serious health risk. This study investigated the attenuation and transport of rotavirus, bacteriophage MS2 and DNA-labelled-glycoprotein-coated silica nanoparticles (DGSnp) in 2 intact cores of silt loam over gravels dosed with wastewater from an OWTS at 3.53 L/day. To simulate a worst-case scenario, experiments were conducted under saturated conditions. The results from 6 experiments demonstrated that the rotavirus and DGSnp reductions were very similar and markedly greater than the MS2 reduction. This was reflected in the peak concentrations, relative mass recoveries, and temporal and spatial reduction rates. For a given log10 reduction, the estimated soil depth required for MS2 was over twice that required for rotavirus and DGSnp. This is the first study in which DGSnp was used as a rotavirus surrogate in soil under wastewater applications. Consistent with previous studies, DGSnp showed promise at mimicking rotavirus attenuation and transport in porous media. The results suggest DGSnp could be used to assess the attenuation capacity of subsurface media to rotavirus. However, DGSnp is not conservative and will underestimate the setback distances required for rotavirus reductions by 3%. On the other hand, separation distances determined using the rotavirus parameters and criteria but based on MS2 attenuation, can be too conservative in some subsurface media. To determine safe and realistic separation distances, it would be beneficial and complementary to apply both conservative virus surrogate using MS2 bacteriophage and representative but non-conservative new virus surrogates using biomolecule-modified silica nanoparticles.
We investigated the microbial contamination in various swimming pools in elementary schools and sporting facilities under normal conditions without a reported outbreak of pathogens. We further elucidated their contamination factors according to usage and water quality control practice and evaluated the effectiveness of various bacteria and viruses as indicators of fecal contamination in those waters. The results showed that the detection of microorganisms varied depending on usage conditions, water quality control practice, and facility characteristics (e.g. outdoors or indoors) . Both Escherichia coli and F-specific bacteriophages were detected by culture methods, suggesting that their complete inactivation is difficult with current water quality control practices. Novel contamination indicators, such as the pepper mild mottle virus, cross-assembly phage, and human-specific HF183 Bacteroides 16S rRNA gene marker, were detected at relatively high frequencies. In particular, the cross-assembly phage and HF183 were considered as effective indicators of human fecal contamination in swimming pools where water quality was controlled by filtration and chlorination. Human enteric viruses were not detected in all of the surveyed swimming pools; however, when those pathogens are excreted from infected individuals to swimming pool waters, they may be present in the waters without losing infectivity.
A obra “Qualidade de vida: da saúde humana à saúde ambiental” foi organizada com o objetivo de reunir e compartilhar conhecimento por meio de artigos escritos por grandes cientistas abordando diferentes aspectos da qualidade de vida, de humanos e animais, destacando como a vida se entrelaça diariamente. Este livro é um alerta para a necessidade de estarmos atentos ao que ocorre ao nosso redor, especialmente em tempos de tantas mudanças, e pela constante busca pelo equilíbrio entre homens e a natureza. Organizada em 5 capítulos, iniciando pela descrição de um estudo relacionando a doença periodontal e qualidade de vida dos pacientes. Essa doença é caracterizada pela presença de um processo inflamatório crônico, devido ao acúmulo de biofilme bacteriano e a resposta do hospedeiro frente a esses patógenos, tendo como consequência a destruição dos tecidos de suporte das estruturas dentais. O capítulo 2, aborda a incorporação de técnicas da medicina chinesa, como a auriculoterapia, para auxiliar no abrandando dos sintomas e sinais clínicos de diversas doenças, como por exemplo, doença renal crônica. O capítulo 3, faz uma revisão da literatura relacionando a qualidade ambiental e seu impacto na saúde humana, por meio dos contaminantes emergentes. As preocupações com esses resíduos devem-se ao fato de permanecerem bioativos no ambiente, e mesmo em concentrações baixas causarem alterações hormonais e metabólicas em animais e humanos. O capítulo 4 apresenta um importante relato do trabalho implementado pelo Laboratório de Virologia Aplicada da Universidade Federal de Santa Catarina, denominado “VigEAI” - Vigilância Epidemiológica Ambiental Integrativa em parceria com diferentes entidades distribuídas por todo o território catarinense no monitoramento de SARS-CoV-2, em efluentes domésticos. Em meio a pandemia de COVID-19, a detecção do RNA viral no esgoto bruto tornou-se uma ferramenta epidemiológica, já que o vírus é excretado pelas fezes humanas. Por último, um estudo de comportamento animal, mostra como a crescente urbanização sobre as áreas peri-urbanas afeta o comportamento da vida selvagem, servindo de alerta sobre a necessidade de monitoramentos constantes em todos os aspectos da qualidade de vida, desde humanos até animais. Assuntos importantes discutidos por profissionais qualificados, e agora ao alcance das suas mãos. A Global Science 4 – GS4 Editora Expertise em Publicações surge do anseio de quatro cientistas de áreas diferentes mas com um objetivo em comum: auxiliar pesquisadores a divulgar seus trabalhos com qualidade, seriedade, agilidade e transparência, deixando sua marca na história da ciência. Publicando conteúdos de qualidade, promovendo o saber e realizando sonhos. Desejamos uma excelente leitura a todos, e que os trabalhos aqui descritos sejam inspiração para outros cientistas.
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.
There is limited published information on the impact of bathing on stream water quality and ecology, except on human pathogens and health. We investigated the relationships between environmental quality of streams and recreational activity at five sites in the Australian Wet Tropics. The streams normally had very low concentrations of nutrients and suspended solids (TSS), but concentrations fluctuated widely during spates, thereby causing difficulties in discriminating impacts. Daily bathing activity disturbed sediments causing an increase in TSS and turbidity, which greatly exceeded national guidelines for maintenance of aesthetic qualities. TSS returned to background levels overnight as bathing areas were flushed clean. Total nitrogen and phosphate concentrations also increased with bather numbers, and phosphate concentrations were directly proportional to bather density. Faecal coliform concentrations were elevated by bathers at one site. Ecological effects of bathers were equivocal and greater on algal than invertebrate assemblages. Water quality degradation, although transient, suggested that some sites were close to their carrying capacity for bathers. Our results show that water quality may vary with local conditions and that cost-effective monitoring and management require development of cause-effect models of water quality processes for each stream site.
Worldwide, fecal indicator bacteria (FIB) evidence coastal water contamination for which sources are unknown. Here, for two FIB-impacted Santa Barbara recreational beaches, hypothesized fecal sources were investigated over three dry seasons (summers) using nearly 2000 field samples of water (ocean, creek, groundwater), sand, sediments, effluent and fecal sources. In years 1 and 2, gull and dog feces were identified as the probable main FIB sources to surf zone waters, yet HF183 human fecal markers were consistently detected. Determining HF183 sources was therefore prioritized, via year 3 sub-studies. In lower watersheds, human and dog wastes were mobilized by small storms into creeks, but no storm drain outfalls or creeks discharged into surf zones. Beach area bathrooms, sewers, and a septic system were not sources: dye tracing discounted hydraulic connections, and shallow groundwater was uncontaminated. Sediments from coastal creeks, downstream scour ponds, and nearshore marine and inter- and supratidal zones contained neither HF183 nor pathogens. Two nearby wastewater treatment plant (WWTP) outfalls discharged HF183 into plumes that were either deep or distant with uncertain onshore transport. Regardless, local sources were evidenced, as surf zone HF183 detection rates mostly exceeded those offshore and nearshore (around boat anchorages). The presence of swimmers was associated with surf zone HF183, as swimmer counts (on weekdays, holidays, weekends, and during races) significantly correlated (p<0.05, n = 196) to HF183 detections. Besides comprehensively assessing all possible fecal sources, this study provides new explanations of chronic low-level human markers in recreational beach surf zones, suggesting likely lowest achievable HF183 thresholds.
Laundering of textiles – clothing, linens, cleaning cloths - functionally removes dirt and bodily fluids which, prevent the transmission and re-exposure to pathogens as well as odor control. Thus, proper laundering is key to controlling microbes that cause illness and produce odors. The practice of laundering varies from region to region and is influenced by culture and resources. This review aims to define laundering as a series of steps that influence the exposure of the person processing the laundry to pathogens – with respect to the removal and control of pathogens and odor causing bacteria, while taking into consideration the types of textiles. Defining laundering in this manner will help better educate the consumer, highlight areas where more research is needed, and how to maximize products and resources.
Control of microorganisms during laundering involves mechanical (agitation, soaking), chemical (detergent, bleach), and physical processes (detergent, temperature). Temperature plays the most important role in terms of pathogen control, requiring temperatures exceeding 40°C to 60°C for proper inactivation. While detergents play a role in reducing the microbial load of laundering through release of microbes attached to fabrics and inactivation of microbes sensitive to detergents (e.g. enveloped viruses). The use of additives (enzymes) and bleach (chlorine, activated oxygen) become essential in washes with temperatures below 20°C, especially for certain enteric viruses and bacteria.
A structured approach is needed which identifies all the steps in the laundering process and attempts to identify each step relative to its importance to infection risk and odor production.
The Lower Pinacanauan de San Pablo River, which is one of the main tributaries of the Cagayan River, possesses good water quality as far as physical and chemical characteristics are concerned. Analyzed physical and chemical characteristics did not surpass the level set on water quality criteria for inland freshwaters under the Department of Environment and Natural Resources-Department Administrative Order of 2016, series no. 8 (DENR-DAO 2016-08). Hence, there are observed aquatic fauna that inhabits the river. Unfortunately, very high fecal coliform counts were analyzed, which greatly affected the water quality status as found in its water quality indices. Fecal coliforms may have originated from untreated sewage, from swine, poultry, or livestock production, and human feces. The fecal coliform posts health risks to humans, which should be emphasized priority action. The overall result of the study implies that it is not advisable for bathing due to the tendency of drinking the water. Therefore, the result of the study should be discussed with the local government units and DENR Region 2 for appropriate activities that will help solve the problems of river pollution.
This study was designed to evaluate the microbial quality and safety of graywater for reuse purposes. The microbial and chemical composition of graywater from shower/bath, wash cycle and rinse cycle of a clothes washing machine was determined. Graywater composed from all sources within a house was also monitored each week over a 2–3-month time period. Samples were taken from a diverse group of families with children (18 months–9 years of age) and without children. Standard plate count bacteria (SPC) ranged from 105 to 1010 colony forming units (cfu) per 100 ml for shower and bath water, and an average of 104 to 106 cfu per 100 ml for total coliforms. Families with small children produced wash cycle graywater containing 106 cfu per 100 ml of fecal coliforms. During investigations on storage of graywater, it was found that total bacterial SPC and coliform baceria increased one order of magnitude. Salmonella atyphimurium and Shigella dysenteriae seeded into graywater were found to persist for at least several days. Poliovirus type 1 added to graywater decreased 99 and 90% at 25 and 17°C, respectively, after 6 d of storage in graywater. These data imply that there may be some risk associated with reuse of graywater when these pathogenic bacteria or viruses are being excreted by an individual producing the graywater.
Bacteriological studies in 1968 and 1969 corroborated earlier findings that a municipal watershed which had been closed to public entry since 1917 yielded water with four to six times the coliform count found in an adjacent mountain watershed open to recreational activities. Similarly, chemical investigations showed higher concentrations of most ions in water from the closed area. Physiological differentiation of coliform and enterococcal bacteria revealed similar types of organisms in both animal droppings and stream water, with fecal coliforms accounting for as much as 70% of the coliform counts observed in the closed area in 1969. Opening of the closed drainage for limited recreation and expanded logging operations in the spring of 1970 coincided with an unexpected decrease in bacterial contamination of that stream. It is postulated that these human activities drove from the watershed a large wild animal population which had contributed substantially to the previous bacterial pollution. It would seem that the practice of closing high-mountain watersheds to public entry is questionable if governmental standards for water quality are to be met, and it also seems that the standards themselves should be reexamined.
An outbreak of gastrointestinal illness in which headache, low grade fever and myalgia were common symptoms occurred among persons who visited a recreational park in Macomb County, Michigan, on July 13–16, 1979. The temporal clustering of onsets of 121 persons who were the first in their house holds to become ill suggested an incubation period ranging from 4–77 hours. A history of swimming in the park's lake was elicited with significantly greater frequency from these persons than from park visitors who were not ill (age standardized odds ratio = 4.8; 95% confidence interval, 1.8–12.7). One hundred twenty-six park visitors who became ill were household contacts of index patients who had swum in the lake; at least 62 of these 126 cases were probably due to secondary transmission. A secondary attack rate of 19% was observed in household contacts who had not visited the park. Serologic studies identified Norwalk virus as the etiologic agent. The source of the contamination of the lake could not be determined. Although some water samples collected just before and after the epidemic period had high coliform counts, the geometric mean coliform density of all samples collected on those days was within the limits established by the Environmental Protection Agency as acceptable for recreational contact water.
Although outbreaks of waterborne disease are probably underrecognized and underreported, the reported data are helpful in identifying water treatment deficiencies as well as in characterizing the epidemiology of waterborne disease.
For 1991 and 1992, 17 states and territories reported 34 outbreaks of disease associated with drinking water, which affected an estimated 17,464 people. A protozoal parasite (Giardia lamblia or Cryptosporidium) was identified as the etiologic agent for seven of the eleven outbreaks for which an agent was determined; the remaining four were due to hepatitis A, Shigella sonnei, or chemicals. A lack of treatment or inadequate treatment accounted for the majority of outbreaks, and most (76 percent) were associated with well water. In addition, eight states reported eleven outbreaks of gastroenteritis associated with unintentional ingestion of recreational water. Six of these outbreaks were caused by Giardia or Cryptosporidium. Ongoing for 22 years, this national surveillance of waterborne disease helps to identify deficiencies in water systems and the etiologic agents associated with outbreaks.
Before the controversy is settled as to whether the public should be allowed to use water supply sources for sport and play, it must first be determined how recreational use affects water quality— if at all. Five completed studies provide arguments for both sides of the question, and two studies yet to be concluded promise further data for resolving the question.
The bacterial contamination from bathers in the water and sand at a beach was investigated. Measurements were made of the composition of the cutaneous bacterial flora released by two bathers as well as the sensitivity of the main contaminants to solar radiation. The variations in bacterial concentration of the sea water and sand were determined at the sea shore over three complete day cycles. Broadly speaking, the concentration of some bacteria increases with the frequency with which the beach is used. Nevertheless, short-period variations seem to be masked by the opposing effects of solar radiation and bathers.
A modeling study was conducted to evaluate the impact of body-contact recreation (e.g., water skiing, jet skiing, swimming) on pathogen concentrations in a source drinking water reservoir under construction in eastern Riverside County in Southern California. A hybridized Monte Carlo-finite segment model was used to predict pathogen concentrations in the reservoir resulting from pathogen inputs associated with shed fecal material and accidental fecal releases (AFRs). Monte Carlo techniques were incorporated into the finite segment model to define characteristics about individual recreators which affect pathogen loading to the reservoir (e.g., infection, pathogen shedding rate, location). Results of simulations are provided in the form of cumulative distribution and probability density functions derived from uncertainty analyses. The model predicted considerable spatial and temporal variability in pathogen concentrations within the reservoir, with elevated levels of Cryptosporidium, rotavirus, and poliovirus in the epilimnion during periods of high recreational use. Predicted Giardia concentrations were lower than the other pathogens. Hypolimnetic concentrations of all pathogens were generally 1–3 orders of magnitude lower than the overlying epilimnetic concentrations. Model results also suggest that field sampling will underestimate the mean, range and variance of pathogen concentrations in the reservoir. The model was further modified to include a particle tracking scheme to allow for transport of aggregated fecal material. Results from simulations using this approach demonstrate a potential for high pathogen loads due to body-contact recreation periodically reaching treatment plants.
In order to examine the temporal relationship between bather load and water quality indicator levels, faecal pollution indicator (faecal coliforms and faecal streptococci) and opportunistic pathogen (Candida albicans and Pseudomonas aeruginosa) levels were monitored hourly in the nearshore waters of a shallow Lake Ontario bathing beach on a hot August day when the bather load was high, and on two overcast August days when the bather load was negligible. On the high bather load day, an increase occurred in the numbers of faecal coliforms and faecal streptococci in the beach water in conjunction with an increase in the bather load; P. aeruginosa levels increased later in the day. There was little apparent relationship between C. albicans levels and the other parameters on the high bather load day. No corresponding increases were observed for any of the monitored parameters on the low bather load days. The results indicate that bather load and sample collection time may influence estimations of recreational water quality based on faecal pollution indicator and P. aeruginosa levels.
Recent epidemiological studies have shown a relationship between swimming in recreational waters meeting bacteriological standards and gastroenteritis with a suggested viral etiology. No previous studies have been conducted in the United States on the occurrence of human pathogenic enteric viruses in freshwater recreational areas. The presence of enteroviruses and rotaviruses was investigated in Oak Creek, Arizona, a heavily used recreational area. Water samples were filtered through positively charged filters (168–1555 I.), eluted with beef extract, and assayed for human enteroviruses and rotaviruses. Eighteen of the 41 recreational water samples were positive for enterovirus or rotavirus. Of these, nine samples exceeded the Arizona State recommended limit of 1 PFU 40 l−1 for full body contact in effluent dominated recreational waters. Several virus positive samples met the recommended fecal coliform standards (200 CFU 100 ml−1) for recreational waters indicating the inadequacy of bacterial standards for monitoring viral water quality. The isolation of the pathogenic enteric viruses (i.e., poliovirus 1, echovirus 1, coxsackievirus B1 and B6 and rotavirus) from this popular recreational water demonstrates the potential for transmission of viral disease.
"An Official report of the American Public Health Association" Incluye índice
Thesis--University of Michigan. Bibliography: p.104-114.
The microbiological quality of forest surface waters in the Greenwater River watershed was examined to investigate the influence of heavy motorized camping in an area with no sanitary facilities. Indicator densities increased during weekend human-use periods when compared to weekdays. Increases in indicator densities were also noted downstream from heavily used camping areas when compared to upstream sites. Seasonal, weekly, and diurnal fluctuations in indicator densities were observed. This study suggests that potential health hazards exist in this watershed during periods of human use.
In August and September 1975, an outbreak of diarrhea occurred in children 1 to 3 1/2 years old attending a day-care center. An investigation revealed overlapping epidemics of shigellosis and giardiasis, with 54% of the children infected with Giardia lamblia. At two other centers 29% and 38% of the children had G. lamblia infection, but none had Shigella. The prevalence of G. lamblia in the day-care children was significantly higher than the 2% prevalence in age-matched children not in day-care centers. Epidemiologic data suggested fecal-oral transmission of the parasite from child to child in the centers and from infected children to other family members.
In July and August 1988, an outbreak of gastroenteritis affected 44 of 60 (73%) persons from 5 separate swimming groups who had used the same swimming pool in Los Angeles. Cryptosporidium was identified in 5 of 8 (63%) stool specimens, and the clinical picture was consistent with Cryptosporidium infection. Resistance of Cryptosporidium to chlorine, an inadequately maintained pool filtration system, repeated exposure to pool water, and possible continuing pool contamination may have contributed to ongoing transmission. Cryptosporidium should be considered a potential etiologic agent of gastroenteritis associated with recreational water use.
To determine the timing of symptoms and oocyst excretion after the acquisition of cryptosporidium infection, we used a screening parasitologic stool examination to identify patients and then contacted them for the collection of retrospective histories and follow-up stool specimens. The study included 68 otherwise healthy patients with an identifiable source and time of infection. All 68 had diarrhea, 61 had abdominal pain, most also had other gastrointestinal symptoms, 33 had fever, and all recovered spontaneously. Among the 50 patients who submitted follow-up stool samples, more than 90 percent of the 610 symptomatic days and of the 136 oocyst-positive stools occurred between days 7 and 28 of infection, the mean incubation period was 7.2 days (range, 1 to 12), and the mean duration of illness was 12.2 days (range, 2 to 26). During the oocyst-excretion period cryptosporidium was detected in 90 percent of Ziehl-Neelsen-stained fecal concentrates. The end of oocyst excretion could be accurately determined in 26 patients; 19 (73 percent) had positive stools after the cessation of symptoms for a mean period of 6.9 days (range, 1 to 15). Fourteen patients were studied for two or more months, and in three of them asymptomatic episodes of oocyst excretion were detected up to two months after clinical recovery. We conclude that many cases of symptomatic cryptosporidiosis occur among immunocompetent patients, some of whom may excrete oocysts even when they have become asymptomatic. Conversely, infected symptomatic patients may occasionally have intermittently negative stools.
During 29 months of prospective longitudinal study of diarrhea in the home, human rotaviruses (HRVs) infected one or more members in 51% of 65 families, 35 of 126 children (28%) and 16 of 124 adults (13%). Within the 33 affected families, 57% of 62 children and 25% of 65 adults were infected. HRV gastroenteritis peaked at 40/100 person years at ages 12 to 23 months and decreased to 5 episodes/100 person years in adults. Among 25 children 0 through 36 months of age who had HRV infection, 88% were symptomatic. Of the 22 children with symptomatic HRV infection, 1 required hospitalization and 8 were seen by their physician for supportive care. HRVs were found in 12% of 216 stools obtained during gastrointestinal illness, but in only 0.2% of 1238 non-illness stools tested. HRV infections were noted as early as October and as late as April. Of 33 families who were studied for 2 seasons, at least 1 individual in each of 3 families experienced HRV infections in both years, but only one, an adult, shed virus and had symptoms in both seasons.
One-hundred-ninety-two stool samples were tested for the presence of human Hepatitis A antigen. Sixteen of these were also evaluated for the presence of infectious virus. All samples were obtained from young and apparently healthy people from endemic areas for Hepatitis A disease. The isolation of the infectious virus from these stools demonstrates clearly the wide diffusion of the virus in these areas, and its transmission by the oral-fecal route.
In the fall of 1985, an outbreak of giardiasis occurred among several swimming groups at an indoor pool in northeast New Jersey. Nine clinical cases were identified, eight of whom had Giardia positive stool specimens. All were female; seven were adults (greater than 18 years) and two were children. The attack rate was highest (39 per cent, 5/13) for the ladies lap group who had exposure on one day. These cases had no direct contact with children or other risk factors for acquiring Giardia. Infection most likely occurred following the ingestion of swimming pool water contaminated with Giardia cysts. The source of Giardia contamination was a handicapped child who had a fecal accident in the pool. He was a member of a group that swam at the same time as the ladies lap group. A stool survey of the handicapped group showed that of the 20 persons tested, nine were positive for Giardia, including the specimen from this child. Examination of the pool records showed that no chlorine levels had been taken on the day of the fecal accident and that on the following day the chlorine level was zero. This is the second report of Giardia transmission among swimming pool attendees. It emphasizes the need to maintain appropriate chlorine levels in swimming pools and to institute measures to clear pools after a fecal accident.
Five healthy young women swam in untreated water of known bacterial quality under a variety of hygienic conditions. Evidence based on bacteriological examination of water samples leads to the following conclusions:
1. There is a marked variation in the number and types of bacteria shed by a bather while swimming and the variations do not seem to be correlated to the differences in personal hygiene or the menstrual period.
2. Faecal organisms may be discharged in considerable numbers by a swimmer after a thorough and careful shower with soap and warm water and yet not be discharged in appreciable numbers by a bather who does not take a shower before swimming.
3. Faecal organisms constitute only a small minority of the total number of viable bacteria that are discharged in swimming pool water by a bather during the act of swimming and as such seem to have limited use as indicators of total bacterial pollution.
4. Members of the genus Staphylococcus are shed in large numbers under all conditions and Staph. aureus is consistently present. Therefore, this genus appears to be a good choice as an index for the determination of body contamination.
5. Further studies are indicated under more stringently controlled hygienic conditions to determine the value of hexachlorophene in reducing microbial flora that a given individual may shed during swimming.
A prospective study was carried out on 200 patients admitted to Fairfield Hospital, Melbourne, Australia, with acute hepatitis
A to determine the frequency with which virus could be detected in their feces. Evidence of infection with hepatitis A virus
(HAV) was obtained by detecting IgM specific for HAV in a single serum sample or by demonstrating a rising titer of antibody
in paired sera by solid-phase radioimmunoassay. HAV was detected in the feces of 59 of the 200 patients by solid-phase radioimmunoassay
and immune electron microscopy. When patients were admitted within one week of the onset of dark urine, 45% were found to
be shedding HAV, whereas only 11% of specimens obtained from patients admitted during the second week contained virus. HAV
was not detected in fecal specimens collected more than 14 days after the onset of dark urine. These findings suggest that
patients admitted to hospital with hepatitis A may still be infectious and that appropriate precautions against fecal contamination
should be maintained.
Data have been gathered and collated from a variety of sources both published and unpublished, dealing with the concentration of enteroviruses in human stools. For polioviruses, a general range of 3.0–6.5 log10 TCD50* per gram of stool was reported, whereas for coxsackieviruses and echoviruses the range has been from 2.0–5.5 log10 TCD50. As human stools average about 100 gm, it is not unusual for an infected person to excrete as much as 10–300 million TCD50 of virus daily.
The results of enterovirus titrations are significantly affected by the types of cultures in which the tests are conducted. With certain kinds of cultures (eg, human kidney for polioviruses), comparative tests showed titers to be at least one log unit higher per gram of stool than the titers of the same strains titrated in monkey kidney cultures. Since almost all of the titrations included in this report were carried out in monkey kidney cultures, the concentration of virus in many cases may be assumed to be ten times higher than that reported.
Some of the data collected also contributed information on the duration of enterovirus excretion. These data reemphasize the fact that a person in the course of an asymptomatic enterovirus infection may excrete the virus over a period of many weeks, with about 50% of those infected continuing to shed virus into the third and fourth weeks of infection.
An outbreak of gastrointestinal illness in which headache, low grade fever and myalgia were common symptoms occurred among persons who visited a recreational park in Macomb County, Michigan, on July 13-16, 1979. The temporal clustering of onsets of 121 persons who were the first in their households to become ill suggested an incubation period ranging from 4-77 hours. A history of swimming in the park's lake was elicited with significantly greater frequency from these persons than from park visitors who were not ill (age standardized odds ratio = 4.8; 95% confidence interval, 1.8-12.7). One hundred twenty-six park visitors who became ill were household contacts of index patients who had swum in the lake; at least 62 of these 126 cases were probably due to secondary transmission. A secondary attack rate of 19% was observed in household contacts who had not visited the park. Serologic studies identified Norwalk virus as the etiologic agent. The source of the contamination of the lake could not be determined. Although some water samples collected just before and after the epidemic period had high coliform counts, the geometric mean coliform density of all samples collected on those days was within the limits established by the Environmental Protection Agency as acceptable for recreational contact water.
Biophysical and biochemical analysis of hepatitis A virus has shown it to be a 27- to 32-nm icosahedral particle with 32 capsomers. The mature virion has a buoyant density of 1.33-1.34 g/cm3, a sedimentation coefficient of 156-160S, and is composed of four polypeptides with molecular weights of 30,000-33,000 (VP1), 24,000-27,000 (VP2), 21,000-23,000 (VP3), and 7,000-14,000 (VP4). The genome of hepatitis A virus consists of a single piece of single-stranded RNA which sediments at 32-35S and has a buoyant density of 1.64 g/cm3. The molecular weight of RNA is 2.25 x 10(6) when measured under nondenaturing conditions and 2.8 x 10(6) when measured under fully denaturing conditions. The genome contains a 40-80 nucleotide sequence of polyadenylic and is capable of infecting cell cultures. These findings, together with the observation that the virion is stable at pH 3.0 and resistant to ether and a temperature of 60 degrees for 1 h, indicate that hepatitis A virus should now be classified as an Enterovirus within the family Picornaviridae.
In June 1977 an outbreak of acute gastroenteritis affected 103 students and teachers at an elementary school in Ohio. The illness typically lasted 24 hours or less and was characterized by vomiting (86%) and cramping (70%), but more than half of the persons involved also reported having nausea, diarrhea, and headache. Similar illness frequently followed in household members (29%) of families with primary cases. Investigation revealed that 70% of the children and teachers who swam in a pool at an all day outing June 1 (4 classrooms) and 55% of those who swam during a similar outing June 2 (2 classrooms) had the onset of acute illness from 12--48 hours later. None of the children who attended the outings but did not swim had a similar illness. The evidence suggested that the primary outbreak was caused by contaminated water in the pool and that person-to-person spread of illness followed. Results of a microbiologic study of pool water were negative for bacterial and viral pathogens. Throat washings, stool specimens, and paired blood samples studied for evidence of pathogens were negative initially, but subsequent serologic studies suggested that infection by Norwalk virus was the cause of the outbreak. The pool chlorinator which was inadvertently unconnected at the time of the school visits was reconnected and an underground leak in the water supply pipes was corrected. No more cases were reported after the pool was drained, cleaned, and reopened.
Enteric illnesses in residents of Tecumseh, Michigan, were studied from 1976 to 1981. The frequency of illness among adults
and children increased each year in the late autumn, usually in November. This peak of illness preceded the main period of
appearance of the rotaviruses, which were less regularly associated with another peak of illness. Rotaviruses were identified
in 3.8% of all stool specimens collected; in specimens from children under two years of age, the annual rate of rotavirus
identification was 10.4%. All rotaviruses were identified during the period from late December to early April. Bacterial pathogens
were isolated from 3.3% of stool specimens, with no concentration in any age group or season. However, most enteric illnesses
in the community were not associated with recognized pathogens. Testing of blood specimens collected in 1976–1978 by complement
fixation confirmed the seasonal pattern of rotavirus activity. Rotavirus infections were documented in all age groups, even
in older adults, and were associated with symptomatic illness.
From September 1979 to July 1980 inclusive, rotaviruses were prospectively detected by electron microscopy (EM) and ELISA
in 82 (29%) of 283 children under two years of age who were admitted to a general pediatric ward in Paris. Rotavirus was found
in 43 (36%) of 119 children with diarrhea and in 40 (24%) of 164 children without diarrhea; thus of 83 children shedding rotavirus,
40 (48%) were not diarrheic. Virus shedding that was not associated with diarrhea was observed in 71% of neonates, in 50%
of one- to six-month-old children, and in 26% of 7–24-month-old children. Rotavirus shedding was statistically correlated
(P < .01) only with those cases of diarrhea with fever and vomiting (DFV syndrome). Consequently, relative risk (RR) for the
DFV syndrome in patients who were shedding virus was 2.07 (P < .001) vs. 0.95 for other types of diarrhea. These observations show that asymptomatic rotaviral infection is not an infrequent
occurrence; that the association between rotavirus and diarrhea is not necessarily an etiologic one; and that the DFV syndrome
appears as a major clinical expression of rotaviral disease. Consequently, recovery of rotavirus from feces is of little diagnostic
significance since it does not give a differentiation between rotavirus-induced and rotavirus-associated diarrhea.
A Giardia infected Washington State child was found to participate in an infant and toddler swim class. A stool survey of 70 child participants revealed a 61 per cent prevalence of Giardia infection. Also, 39 per cent of 53 mothers and 28 per cent of 21 fathers were Giardia positive. None of the non-swimming playmates were positive. Thirty-five per cent of 23 children exposed only at a better maintained pool to which the classes had been moved four weeks prior to the survey were positive. No evidence of transmission to non-swim class pool users was found.
We prospectively evaluated excretion of Giardia lamblia in children in day care centers in Houston by conducting two prevalence studies of 600 children enrolled in 30 DCC, day care centers, and an 18-month longitudinal study in 82 children in one center. In the two prevalence surveys, Giardia cysts were identified in 72 (21%) and 67 (26%) children, respectively, who provided stool specimens. Trophozoites were found in 15 (4%) and 8 (3%), respectively. There was no correlation between the frequency of recent diarrheal episodes and the finding of Giardia. Stool specimens containing cysts were significantly (P less than 0.0001) more frequent in the 13- to 30-month-old children than in children younger than 12 months. Children attending day care centers for more than 3 months were more likely to be excreting Giardia than those attending for less than 3 months. In the longitudinal study, cysts were detected in stool specimens from 27 (33%) of the 82 children at least once during the survey. Twelve children had Giardia cysts in weekly stool specimens for a mean of 6.2 +/- 1.2 months and trophozoites for 3.3 +/- 1.2 months. The number of enteric symptoms observed in children and the classification of nutritional status based on monthly height and weekly weight measurements did not differ significantly when infected and noninfected children were compared. Asymptomatic Giardia excretion in children younger than 36 months is common and appears to be well tolerated.
Five surveys of 1,731 children for stool ova and parasites (1971 to 1981) in a rural county provide a unique perspective on naturally occurring, nonepidemic giardiasis. Currently white children in day care centers in Hampton County, South Carolina, experience attack rates of 26%. They enter the first grade with at least six times as much infection as those who do not attend day care. A trend toward more giardiasis linked to working mothers and day care is evident among white preschool children. This has not yet occurred among black preschool-aged children. These and other epidemiologic data indicate that as few as 100 children can maintain endemic levels of infection in a county of 18,000 residents. Person-to-person transmission in the day care setting is sufficient to explain this county's rising rate of stool positivity of infection (8% of all stool specimens submitted to the state laboratory).
An outbreak of Cryptosporidiosis occurred over three months in a British Columbia community, peaking in December 1990. Results of the case-control study and illness surveys support the hypothesis that transmission occurred in a public children's pool at the local recreation centre. Analysis using lab-confirmed cases revealed a matched odds ratio of 4.5 [95% CI 0.97, 20.83], and using clinical cases an unmatched odds ratio of 12.8 [95% CI 3.68, 46.77], associated with swimming in the children's pool within two weeks prior to onset of illness. Other risk factors were not significant. Attack rates in various groups of children's pool users ranged from 8% to 78%. The children's pool was closed for steam cleaning and disinfection. Unusually frequent defecations including liquid stools had occurred before and during the outbreak. Improvements were instituted for removal of feces and superchlorination of pool water.
The occurrence and survival of viruses in municipal solid waste. Dissertation Abstracts Soiled disposable diapers: A potential source of viruses
- M L Peterson
M.L. Peterson (1972). The occurrence and survival of viruses in municipal solid waste. Dissertation Abstracts. 33a3, 2232-B±2233-B. Ann Arbor, MI. M.L. Peterson, Soiled disposable diapers: A potential source of viruses. Amer J Public Hlth 64, 912±914 (1974).
Standard Methods for Water and Wastewater Analysis
- Apha
APHA. American Public Health Association, Standard Methods for Water and Wastewater Analysis (Washington, DC, 1998).
Clinical features of rotavirus infections
- T H Flewett
T.H. Flewett, Clinical features of rotavirus infections, in Virus Infections of the Gastrointestinal Tract, edited by D.A.J. Tyrell, A.Z. Kapikian (Marcel Dekker Inc., NY, 1982), pp. 125±146. J.P. Fox, C.E. Hall, Viruses In Families (PSG Publishing Company, Inc., Littleton, MA, 1980).
Hepatitis A virus Intestinal parasites in Arkansas
- F B Hollinger
- J Ticehurst
F.B. Hollinger, J. Ticehurst, Hepatitis A virus, in Virology, edited by B.N. Fields, D.M. Knipe (Lippincott-Raven, Philadelphia, PA, 1990), pp. 631±637. R.T. Howell, B.S. Waldron, Intestinal parasites in Arkansas. J Arkansas Med Soc 75, 212±214 (1978).
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Detection of Giardia cysts in drinking water: State-of-the-art
- W Jakubowski
W. Jakubowski, Detection of Giardia cysts in drinking water: State-of-the-art, in Giardia and Giardiasis, Biology,
Pathogenesis and Epidemiology, (Plenum Press, NY, 1984), pp. 263±285.
Sanitation and Disease
- R G Feachem
- D J Bradley
- H Garelick
- D D Mara
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Effects of swimmers on the microbiological quality of recreational waters: A simulation study Cryptosporidum and other protozoa including Isospora, Sacrocysts, Blantidium coli and Blastocysts Swimming associated cryptospor-idsis
- B G Smith
- A P Dufour
B.G. Smith, A.P. Dufour, Effects of swimmers on the microbiological quality of recreational waters: A simulation study, Abstracts of the Annual Meeting of the American Society for Microbiology (American Society for Microbiology. Washington, DC, 1994), pp. 406. R. Soave, C.S. Weikel, Cryptosporidum and other protozoa including Isospora, Sacrocysts, Blantidium coli and Blastocysts, in Principles and Practice of Infectious Diseases, (Churchill Livingstone Inc., NY, 1990), pp. 2122±2130. F.J. Sorvillo, K. Fujioka, B. Nahlen, M.P. Tonney, R. Kebabjian, L. Mascola, Swimming associated cryptospor-idsis. Amer J Public Hlth 82, 742±744 (1992).
Concentration of viruses from water by membrane ®lters A quantitative analysis of the effects of bathers on recreational water quality, 5th International Water Pollution Research Conference
- S M Goyal
- C P Gerba
S.M. Goyal, C.P. Gerba, Concentration of viruses from water by membrane ®lters, in Methods in Environmental Virology, edited by C.P. Gerba, S.M. Goyal (Marcel-Dekker, Inc., NY, 1982), pp. 59±116. N.B. Hanes, A.J. Fossa, A quantitative analysis of the effects of bathers on recreational water quality, 5th International Water Pollution Research Conference 1970 preprint. 1-1A-9a1 through HA 9a8 (Pergamon Press, London, Great Britain, 1970).
Outbreaks caused by Giarda and Cryptosporidium associated with swimming pools
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- P Gerba
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