ArticleLiterature Review

# Lifting the lid on toilet plume aerosol: A literature review with suggestions for future research

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## Abstract

Background: The potential risks associated with "toilet plume" aerosols produced by flush toilets is a subject of continuing study. This review examines the evidence regarding toilet plume bioaerosol generation and infectious disease transmission. Methods: The peer-reviewed scientific literature was searched to identify articles related to aerosol production during toilet flushing, as well as epidemiologic studies examining the potential role of toilets in infectious disease outbreaks. Results: The studies demonstrate that potentially infectious aerosols may be produced in substantial quantities during flushing. Aerosolization can continue through multiple flushes to expose subsequent toilet users. Some of the aerosols desiccate to become droplet nuclei and remain adrift in the air currents. However, no studies have yet clearly demonstrated or refuted toilet plume-related disease transmission, and the significance of the risk remains largely uncharacterized. Conclusion: Research suggests that toilet plume could play a contributory role in the transmission of infectious diseases. Additional research in multiple areas is warranted to assess the risks posed by toilet plume, especially within health care facilities.

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... This practice, along with individuals infected with NV using residential bathrooms and NVs resilience in the environment, might explain why NV was detected at a wastewater treatment facility 18,19 . The mechanisms involved when a toilet is flushed have been shown to create aerosols from inside the toilet bowl 22 . Furthermore, two additional studies have found that biological materials (e.g., bacteria and virus) contained in toilet bowl water can also become aerosolized during flushing 23,24 . ...
... They successfully detected microorganisms in the air after flushing a seeded toilet 23 . Another study analyzed whether the type of toilet had an impact on aerosol generation, and found that flushometer (FOM) type toilets commonly found in healthcare, educational, and governmental buildings significantly increased the amount of aerosol generated compared to gravity-fed toilets 22 . This study hypothesized that toilet plume airborne infection risks are likely from viruses, of which the most significant is NV 22 . ...
... Another study analyzed whether the type of toilet had an impact on aerosol generation, and found that flushometer (FOM) type toilets commonly found in healthcare, educational, and governmental buildings significantly increased the amount of aerosol generated compared to gravity-fed toilets 22 . This study hypothesized that toilet plume airborne infection risks are likely from viruses, of which the most significant is NV 22 . Healthcare workers (HCW) may not currently use any precautions to prevent exposure to aerosolized NV (i.e., workers are at risk as they do not use respiratory protection or face shields when toilet flushing). ...
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Murine norovirus (MNV) was used as a surrogate for human viral pathogens (e.g., norovirus) to determine if toilet flushing resulted in the aerosolization of virus. A flushometer type toilet was seeded with a viral solution of 10⁵ and 10⁶ PFU mL⁻¹ of MNV and then flushed. Upon flushing, two bioaerosol samplers were activated to collect aerosolized MNV. Prior to the experiment, two optical particle counters monitored particle size and number distribution of aerosol produced from flushing a toilet across height, position, and side. The location with the highest mean particle concentration, was behind the toilet and 0.15 m above the toilet bowl rim, which is where bioaerosol sampling occurred. Bioaerosol and toilet water samples were collected, extracted and then quantified using RT-ddPCR. The concentration of MNV collected after seeding the toilet water ranged from 2.18 × 10⁵ to 9.65 × 10⁶ total copies of MNV. Positive samples of airborne MNV were detected with collected concentrations ranging from 383 to 684 RNA copies/m³ of air. This study provides evidence that viral pathogens may be aerosolized when a toilet is flushed. Furthermore, the MNV used in this study is a model organism for human norovirus and may be generalizable to other viral pathogens (e.g., coronavirus). This study suggests that virus is aerosolized from toilet flushing and may contribute to human exposure to viral pathogens.
... This process drives bioaerosol emissions from the toilet bowl into the toilet's surrounding air and eventually spreads them (Fig. 1). Hence, as can be seen from several studies, the generation of bioaerosols during flushing a toilet is likely to be affected by the numerous interactions between air and liquid, the flushing ways, and toilet structures (Fig. 2) [90,91]. ...
... The relationship between inhalable airborne particles generated from disturbed sewage and infection spread has been suggested for a century. Therefore, scientists have formerly been concerned that toilet plumes pose a risk for transmitting infectious diseases because a large number of bioaerosols can be generated by the high pressure and turbulence of toilet flushing [90]. Nevertheless, a few research studies have been dedicated to this issue [80,93]. ...
... Hence, existing scientific research on sewage aerosolization from toilets has demonstrated that flushing a toilet may cause to release of up to 80,000 bioaerosols into the toilet's indoor air and the toilet environment, floating above the toilet area around one meter (3.2 ft). Therefore, these bioaerosols can easily be floating in air currents due to their low settling velocity, finally depositing on the toilet seat, toilet lid, and the toilet's surface surroundings [90,92,96]. Other authors like Mendes and Lynch observed similar findings. ...
Article
The detection of SARS-CoV-2 RNA in raw and treated wastewater can open up a fresh perspective to waterborne and aerosolized wastewater as a new transmission route of SARS-CoV-2 RNA during the current pandemic. The aim of this paper is to discuss the potential transmission of SARS-CoV-2 RNA from wastewater aerosols formed during toilet flushing, plumbing failure, wastewater treatment plants, and municipal wastewater reuse for irrigation. Moreover, how these aerosols might increase the risk of exposure to this novel coronavirus (SARS-CoV-2 RNA). This article supplies a review of the literature on the presence of SARS-CoV-2 RNA in untreated wastewater, as well as the fate and stability of SARS-CoV-2 RNA in wastewater. We also reviewed the existing literatures on generation and transmission of aerosolized wastewater through flush a toilet, house's plumbing networks, WWTPs, wastewater reuse for irrigation of agricultural areas. Finally, the article briefly studies the potential risk of infection with exposure to the fecal bioaerosols of SARS-CoV-2 RNA for the people who might be exposed through flushing toilets or faulty building plumbing systems, operators/workers in wastewater treatment plants, and workers of fields irrigated with treated wastewater - based on current knowledge. Although this review highlights the indirect transmission of SARS-CoV-2 RNA through wastewater aerosols, no research has yet clearly demonstrated the role of aerosolized wastewater in disease transmission regarding the continuation of this pandemic. Therefore, there is a need for additional studies on wastewater aerosols in transmission of COVID-19.
... Johnson et al. (21) characterized, by size, the emissions spread by three different types of toilets when flushed. They observed that the emissions in the form of droplets, meaning having a diameter of 5 µm and more, constitute the smallest quantity of particles emitted, regardless of the model of toilet, compared to aerosols (smaller than 5 µm). ...
... According to the results of Johnson et al. (21), all of the emissions produced when a toilet is flushed end up in the form of an aerosol. This observation is corroborated by Knowlton (24). ...
Article
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In COVID-19 infection, the emissions of droplets and aerosols produced by the respiratory tract of contaminated subjects may represent a high risk of spreading the SARS-COV-2 virus in the environment. Thus, studies have shown that there is, at least, another source of droplets and aerosols in which viral particles of SARS-COV-2 can be found. It happens after flushing of toilet to dispose of the stools of a patient who has contracted COVID-19. The presence of viral particles of SARS-COV-2 in the stool could be linked to the concentration of angiotensin-converting enzyme 2 (ACE2) found on the surface of intestinal cells. Therefore, there is a reason to wonder whether the emission of viral particles by activating a toilet flush could represent an important potential risk of contamination for health care workers. To investigate this hypothesis, we have correlated different studies on the production of droplets and aerosols as well as the presence of viral particles following flush of toilet. This pooling of these studies led to the following conclusion: the precautionary principle should be applied with regard to the potential risk represented by viral particles of SARV-COV-2 in the stool when flushing the toilet.
... Park et al. recently demonstrated that exposure to CR-KP-colonized/infected patients was associated with environmental (toilet/hopper) CR-KP contamination [13]. Furthermore, it has been shown that a large amount of bacteria or viruses might remain in toilet bowls after flushing due to adsorption to porcelain, with gradual partial elution occurring after multiple flushes [16][17][18]. ...
... While the physical effect of droplet dispersion during flushing has been investigated [16,17], the dispersion of droplets during urination has not been studied and remains unaddressed in scientific studies. Hence, it is unknown whether droplet dispersion during urination contributes to the spread of microorganisms. ...
Article
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Background In the health care setting, infection control actions are fundamental for containing the dissemination of multidrug-resistant bacteria (MDR). Carbapenemase-producing Enterobacterales (CPE), especially Klebsiella pneumoniae (CR-KP), can spread among patients, although the dynamics of transmission are not fully known. Since CR-KP is present in wastewater and microorganisms are not completely removed from the toilet bowl by flushing, the risk of transmission in settings where toilets are shared should be addressed. We investigated whether urinating generates droplets that can be a vehicle for bacteria and explored the use of an innovative foam to control and eliminate this phenomenon. Methods To study droplet formation during urination, we set up an experiment in which different geometrical configurations of toilets could be reproduced and customized. To demonstrate that droplets can mobilize bacteria from the toilet bowl, a standard ceramic toilet was contaminated with a KPC-producing Klebsiella pneumoniae ST101 isolate. Then, we reproduced urination and attached culture dishes to the bottom of the toilet lid for bacterial colony recovery with and without foam. Results Rebound droplets invariably formed, irrespective of the geometrical configuration of the toilet. In microbiological experiments, we demonstrated that bacteria are always mobilized from the toilet bowl (mean value: 0.11 ± 0.05 CFU/cm²) and showed that a specific foam layer can completely suppress mobilization. Conclusions Our study demonstrated that droplets generated from toilets during urination can be a hidden source of CR-KP transmission in settings where toilets are shared among colonized and noncolonized patients.
... The potential for aerosolization of pathogens during toilet/urine flushing has received a lot of attention, especially in concerning emerging pathogens such as SARS, Ebola, and Clostridium difficile. All the research indicates that significant aerosolization can occur resulting in potential transmission of pathogens by inhalation and via fomite contamination (Johnson et al. 2013a). The degree of aerosolization is dependent upon several factors listed in Table 4. ...
... While large droplets settle out within a few minutes, smaller may persist and continued to settle out on surfaces for 90 min (Best et al. 2012;Knowlton et al. 2018). Residual levels of microorganisms may also remain in the bowl after the initial flush, resulting in aerosolization of bacteria after repeated flushes (Gerba et al. 1975;Johnson et al. 2013aJohnson et al. , 2017. ...
Article
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The goal of good toilet hygiene is minimizing the potential for pathogen transmission. Control of odors is also socially important and believed to be a societal measure of cleanliness. Understanding the need for good cleaning and disinfecting is even more important today considering the potential spread of emerging pathogens such as SARS‐CoV‐2 virus. While the flush toilet was a major advancement in achieving these objectives, exposure to pathogens can occur from failure to clean and disinfectant areas within a restroom, as well as poor hand hygiene. The build‐up of biofilm within a toilet bowl/urinal including sink can result in the persistence of pathogens and odors. During flushing, pathogens can be ejected from the toilet bowl/urinal/sink and be transmitted by inhalation and contaminated fomites. Use of automatic toilet bowl cleaners can reduce the number of microorganisms ejected during a flush. Salmonella bacteria can colonize the underside of the rim of toilets and persist up to 50 days. Pathogenic enteric bacteria appear in greater numbers in the biofilm found in toilets than in the water. Source tracking of bacteria in homes has demonstrated that during cleaning enteric bacteria are transferred from the toilet to the bathroom sinks and that these same bacteria colonize cleaning tools used in the restroom. Quantitative microbial risk assessment has shown that significant risks exist from both aerosols and fomites in restrooms. Cleaning with soaps and detergents without the use of disinfectants in public restrooms may spread bacteria and viruses throughout the restroom. Odors in restrooms are largely controlled by ventilation and flushing volume in toilet/urinals. However, this results in increased energy and water usage. Contamination of both the air and surfaces in restrooms is well documented. Better quantification of the risks of infection are needed as this well help determine what interventions will minimize these risks.
... 8 Toilet plume could play a contributory role to the transmission of enteric diseases. 9,10 Common toilet hygiene measures include handwashing, hand drying, disinfecting, or covering the toilet seat surface before use, and flushing the toilet with the lid closed. 4,9,11,12 Our previous article revealed a range of inappropriate handwashing practices among Chinese in Hong Kong, from not washing at all to washing without soap. ...
... 9,10 Common toilet hygiene measures include handwashing, hand drying, disinfecting, or covering the toilet seat surface before use, and flushing the toilet with the lid closed. 4,9,11,12 Our previous article revealed a range of inappropriate handwashing practices among Chinese in Hong Kong, from not washing at all to washing without soap. 13 Other toilet use practices were identified, such as not covering toilet lid before flushing, stepping on toilet seats, and spitting into toilet bowls or hand basins. ...
Article
Toilet hygiene is an important preventive measure for infectious diseases, including severe acute respiratory syndrome (SARS) and COVID-19. This study explored public’s opinions on improving toilet environment and hygiene practices in Hong Kong. A mixed-method approach was applied. We conducted 4 focus groups plus 3 individual interviews among the Hong Kong Chinese, followed by a questionnaire survey with 300 respondents recruited from various districts. Difference in response distributions between groups with different demographics was tested by Pearson χ ² test. Instead of advocating for advanced toilet facilities, respondents were mostly concerned about basic hygiene issues. Malfunctioning facilities resulting from poor toilet management, such as clogged toilets, stained facilities, and problematic flushing systems, were most cited as barriers to toilet hygiene practices. Three quarters of the survey respondents expressed concerns over worn and poorly maintained toilets, shortage of janitors, and cleansing supplies. However, respondents who were older ( P < .001), less educated ( P < .001), and had lower income ( P = .001) were significantly more likely to find hygiene conditions in public toilets satisfactory. The findings reflected the substandard of the current provisions as a developed city in Asia. Enhanced efforts by the government to maintain basic toilet supplies and facilities is the key to improving public compliance to toilet hygiene practices.
... Flush toilets tend to produce aerosols in substantial quantities when flushed. Some of these aerosols, containing microbes, desiccate to become droplet nuclei above the toilet within 5 minutes and up to 90 minutes post-flush, with the toilet seat raised [56]. They are carried in air currents as viable forms small enough to get translocated through the nasal passages during inhalation. ...
... The ability to cause infection depends on the ability of the pathogen to survive environmental conditions, the number of organisms inhaled, their virulence and the immune status of the host. Available evidence suggests the potential for airborne transmission of norovirus, Severe Acute Respiratory Syndrome (SARS) coronavirus and influenza, since these can be shed in faeces and vomit which is often disposed of in toilets [56]. Infections of the respiratory tract such as influenza can trigger asthmatic episodes in predisposed persons. ...
Article
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Background A previous multi-site study involving lower- and middle-income countries demonstrated that asthma in older adults is associated with long-term exposure to particulate matter, male gender and smoking. However, variations may occur within individual countries, which are relevant to inform health promoting policies as populations live longer. The present study estimates asthma prevalence and examines the sociodemographic characteristics and environmental determinants associated with asthma in older adults in Ghana. Methods This study utilised data from the nationally representative World Health Organization Study on global AGEing and adult health (SAGE) Ghana Wave 2. A final sample of 4621 individuals residing in 3970 households was used in analytical modelling. Factors associated with asthma were investigated using single level and multilevel binary logistic regression models. Results Asthma was reported by 102 (2.2%) respondents. Factors associated with asthma in the univariate model were: those aged 60–69 (OR = 5.22, 95% CI: 1.24, 21.95) and 70 or more (OR = 5.56, 95% CI: 1.33, 23.26) years, Ga-Adangbe dialect group (OR = 1.65, 95% CI: 1.01, 2.71), no religion (OR = 3.59, 95% CI: 1.77, 7.28), having moderate (OR = 1.76, 95% CI: 1.13, 2.75) and bad/very bad (OR = 2.75, 95% CI: 1.58, 4.80) health state, and severe/extreme difficulty with self-care (OR = 3.49, 95% CI: 1.23, 9.88) and non-flush toilet facility (OR = 0.62, 95% CI: 0.39, 0.99). Factors independently associated with asthma in the adjusted models were: those aged 60–69 (OR = 4.49, 95% CI: 1.03, 19.55) years, father with primary education or less (OR = 0.40, 95% CI: 0.17, 0.94), no religion (OR = 2.52, 95% CI: 1.18, 5.41), and households with non-flush toilet facility (OR = 0.58, 95% CI: 0.35, 0.96). Significant residual household-level variation in asthma was observed. Over 40% of variance in asthma episodes could be attributable to residual household-level variations. Conclusion Individual as well as household factors were seen to influence the prevalence of asthma in this national survey. Clinical management of these patients in health facilities should consider household factors in addition to individual level factors.
... Bioaerosols generated during toilet flushing were first reported by Jessen who detected the bacteria that seeded around the toilet after flushing (Johnson et al. 2013b). This experiment has thus aroused an increasing concern on the health and safety of toilet. ...
... Such upward airflow vortex can expel bioaerosols from bowl to air above the toilet, and thus accelerate the spreading of bioaerosols ). In the 1950s, Jessen et al. firstly proposed the concept that toilet flushing might lead to the generation of bioaerosols (Johnson et al. 2013b). In that study, Serratia marcescens was concentrated into the toilet before flushing; meanwhile, the sedimentation plates were placed around the toilet at different distances to collect the settled bioaerosols. ...
Article
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The aerosols harboring microorganisms and viruses released from the wastewater system into the air have greatly threatened the health and safety of human beings. The wastewater systems, including toilet and wastewater treatment plant (WWTP), are the major locations of epidemic infections due to the extensive sources of aerosols, as well as multifarious germs and microorganisms. Viruses and microorganisms may transport from both toilet and hospital into municipal pipes and subsequently into WWTP, which accounts for the main source of bioaerosols dispersed in the air of the wastewater system. This review aims to elaborate the generation, transmission, and diffusion processes of bioaerosols at toilet and WWTP. Moreover, the main factors affecting bioaerosol transmission and the corresponding prevention strategies for the airborne and inhaled bioaerosols are also discussed. Collectively, this review highlights the importance of managing bioaerosol occurrence in the wastewater system, which has aroused increasing concern from the public.
... The viruses remain on the toilets' seats after being used by COVID-19 patients and carriers [14]. Studies revealed that massive particles are transported upward when flushing, with substantial quantities of infectious aerosols reaching above the toilet seat to spread the virus [15][16][17][18]. In addition, if wiping after toilet use has not been done properly, the pathogens may remain in the hands of the infected person and contaminate all surfaces being touched within the toilet area. ...
Article
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Background Hygiene behaviors in public toilets are important to prevent the transmission of infectious diseases, especially during the pandemic. All through the novel coronavirus (COVID-19) pandemic, governments in many countries published guidance on personal hygiene for the general population to prevent disease transmission. This study aimed to investigate improvements in residents’ hygiene awareness and behaviors in public toilets before and during the pandemic. Methods We recruited 316 residents between November and December 2018 before the pandemic, and 314 residents between December 2020 and January 2021 during the pandemic in the same study sites in Hangzhou, a well-developed city in China. Residents’ hygiene behaviors in public toilets, hygiene awareness, risk perception, and sociodemographic factors were collected. Bivariate analysis and multivariable logistic regressions were used to test the differences between the two rounds. We conducted an observational study to record the provision of hygiene amenities at toilets during the pandemic. Results After controlling for sociodemographic factors (gender, marital status, age, education level, and monthly household income), compared with respondents recruited before the pandemic, respondents recruited during the pandemic were more likely to perceive the risks of infection when using public toilets (aOR = 1.77, 95%CI [1.20, 2.60]), and were more likely to be aware of the risks of touching contaminated toilet facilities (aOR = 1.72, 95%CI [1.17, 2.54]) and the risks of not using soap to wash one’s hands after using the toilet (aOR = 1.93, 95%CI [1.38, 2.72]). They were more likely to always clean their toilet seat with alcohol (aOR = 1.88, 95%CI [1.01, 3.51]), wash hands with soap (aOR = 1.52, 95%CI [1.09, 2.10]) and dry their hands with a dryer (aOR = 1.78, 95%CI [1.16, 2.71]), but they were less likely to always wash their hands after using the toilets (aOR = 0.57, 95%CI [0.32, 1.00]). Among 70 public toilets observed, 9 provided alcohol for toilet seat disinfection, 52 provided soap, 33 provided paper towels, and 41 had working hand dryers. Conclusions Despite the overall improvement, residents’ hygiene behaviors in public toilets and the supply of hygiene amenities were still suboptimal during the pandemic. Further hygiene education and an adequate supply of hygiene amenities in public toilets are needed to promote residents’ hygiene behaviors.
... The aerosols from showerheads can contribute to the increased density of opportunistic pathogens inhabiting water systems; it is estimated that Legionella is greater than 10 2 CFU/m 3 in shower air [80]. Aerosols with microbes can also be generated after flushing the toilet [81]. Fecal pathogens (e.g., Clostridium difficile) can be identified in aerosols collected from 25 cm above the toilet after frequently flushing and even 90 min after the most recent flush [82]. ...
Article
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Abstract The exposome depicts the total exposures in the lifetime of an organism. Human exposome comprises exposures from environmental and humanistic sources. Biological, chemical, and physical environmental exposures pose potential health threats, especially to susceptible populations. Although still in its nascent stage, we are beginning to recognize the vast and dynamic nature of the exposome. In this review, we systematically summarize the biological and chemical environmental exposomes in three broad environmental matrices—air, soil, and water; each contains several distinct subcategories, along with a brief introduction to the physical exposome. Disease‐related environmental exposures are highlighted, and humans are also a major source of disease‐related biological exposures. We further discuss the interactions between biological, chemical, and physical exposomes. Finally, we propose a list of outstanding challenges under the exposome research framework that need to be addressed to move the field forward. Taken together, we present a detailed landscape of environmental exposome to prime researchers to join this exciting new field.
... Air age refers to the time elapsed from the time the air particles enter the room to a certain point in the room, reflecting the freshness of the indoor air. Air age can be used to comprehensively measure the ventilation effect in a room and is an important indicator for evaluating the IAQ [28]. In general, the younger the age of the air, the higher the IAQ. ...
Article
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Poor indoor air quality reduces the comfort experienced in the environment and can also harm our physical health. Mechanical ventilation design plays an important role in improving the indoor environment and the safety of public toilets. Therefore, in this study, we aimed to evaluate public toilet ventilation design schemes through a digital twin to determine the most effective scheme for reducing indoor pollutant concentrations. In this study, we used Autodesk Revit to create a digital twin BIM of different ventilation systems. We simulated the diffusion of pollutants in these models using computational fluid dynamics (CFD)-based methods, and we used DesignBuilder to simulate building energy consumption. From the perspective of architectural design, we determined measures important for reducing the concentration of air pollutants by increasing the number and volume of air exchanges and controlling the installation height of exhaust vents. The results show that the ventilation design of an all-air air conditioning system with an exhaust height of 400 mm can remarkably improve the indoor environmental health and ventilation efficiency of public toilets, while consuming 20.4% less energy and reducing carbon emissions by 30,681 kg CO2.
... While many studies have been conducted on the fecal-oral route for transmission of enteric diseases, studies on aerosol transmission of enteric pathogens in places with poor sanitation and associated risk of infection are limited in the literature. Numerous studies found enteric microorganisms in aerosols emitted from land application of biosolids (Dungan, 2014;Viau et al., 2011), concentrated animal feeding operations (Jahne et al., 2015;Millner, 2009), and toilet flushing (Johnson et al., 2013;Wilson et al., 2020). Our recent work detected multiple enteric pathogens in aerosols sampled near open waste canals (OWCs) (Rocha-Melogno et al., 2020;Ginn et al., 2021). ...
Article
The aeromicrobiological transmission pathway of enteric pathogens in places with unsafe sanitation services is poorly understood. In an attempt to partly fill this knowledge gap, we assessed the potential public health impact of bioaerosols near open waste canals (OWCs) using Quantitative Microbial Risk Assessment (QMRA). We used data acquired in La Paz, Bolivia to characterize the risk of disease that aerosolized enteric pathogens may pose through food, fomites and inhalation (all followed by ingestion). Three reference pathogens were selected to conduct the assessment: enterotoxigenic Escherichia coli (ETEC), Shigella flexneri, and Campylobacter jejuni. Inhalation followed by ingestion had the highest median infection risk per event i.e. 3 × 10⁻⁵ (3 infections for every 100,000 exposures), compared to contaminated food e.g. 5 × 10⁻⁶ and fomites e.g. 2 × 10⁻⁷, all for C. jejuni infections. Our sensitivity analysis showed that bacterial fluxes from the air were the most influential factor on risk. Our results suggest that fecal bacterial aerosols from OWCs present non-negligible risks of infection in La Paz, with median annual infection risks by C. jejuni being 18 (food), and 100 (inhalation) times greater than the EPA's standard for drinking water (1 × 10⁻⁴). We included two of the QMRA models presented here in a novel web application we developed for user-specified application in different contexts.
... En människa avger miljontals aerosolpartiklar varje timme genom hudfragment som lossnar vid rörelser och friktion mot kläder (Bhangar et al., 2016, Licina et al., 2017. Mängder av luftburna droppar fulla av mikroorganismer sprids från toalettspolningar (Johnson et al., 2013). Inom sjukvården finns vårdmoment som förmodas sprida extra mycket virusinnehållande aerosol, så kallade aerosolgenererande procedurer (AGP), även om mycket tyder på att många av dessa procedurer är jämförelsevis svaga aerosolkällor (Alsved et al., 2020a, Hamilton et al., 2021, Thuresson et al., 2021, Tran et al., 2012. ...
Article
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Att spridning av sjukdomsframkallande luftvägsvirus kostar samhället enorma resurser har blivit uppenbart för alla under covid-19, men ovälkomna virus har varit människans följeslagare genom hela historien och ständigt uppkommer nya varianter med särskilt hög smittsamhet eller dödlighet. Riskerna har ökat med befolkningstillväxt och globalisering. Samtidigt har våra förutsättningar att skydda oss också blivit bättre genom ökad kunskap och framsteg inom medicin och teknik. Syftet med denna kunskapssammanställning är att beskriva smittvägar, riskfaktorer och skyddsåtgärder för infektiös luftvägssjukdom och därmed bidra till en minskad smittrisk vid arbetsplatser. Mycket av innehållet bygger på forskning om influensa och covid-19, men även en rad andra luftvägsinfektioner är inkluderade. Spridning av virus har här delats upp i tre smittvägar: inandning, direkt deponering och kontakt. Risken för smitta via inandning av virus är särskilt stor när avstånden mellan människor är korta och uppehållstiden lång i lokaler med dålig ventilation. Risken ökar om det också pågår aktiviteter som innebär spridning av virusinnehållande aerosolpartiklar till luften, såsom högt tal eller sång eller vissa medicinska procedurer, eller om den inandade luftmängden är förhöjd, som vid tungt arbete. Virusöverföring via direkt deponering sker när stora smittbärande droppar stänker direkt på en mottagare vid exempelvis hosta. Virusspridning via både inandning och direkt deponering sker på olika sätt genom luften, men benämns här inte ”luftsmitta” eftersom detta begrepp åtminstone enligt klassisk medicinsk indelning syftat på (effektiv) smitta via inandning över avstånd mer än enstaka meter och eftersom det främst använts för sjukdomar som är mycket allvarliga och därför kräver extrema skyddsåtgärder. Smitta via kontakt kan ske antingen via direkt beröring eller genom mellanled, som handtag eller andra ytor. Samtliga tre smittvägar är välbelagda för luftvägsvirus i den vetenskapliga litteraturen, men deras relativa betydelse varierar beroende situation, virustyp och interventioner för att minska smitta. För covid-19 pekar mycket forskning mot att inandning är en dominerande smittväg i många miljöer. Vissa yrkesgrupper, särskilt inom vårdsektorn, löper en förhöjd risk att smittas av luftvägsvirus. En lång rad skyddsåtgärder finns tillgängliga för att på olika sätt minska smittrisker: distans, hygien, fysiska barriärer, ventilation, administrativa åtgärder (exempelvis information, regleringar, kontroller, checklistor) och personlig skyddsutrustning. De flesta av dessa åtgärder har starkt stöd av vetenskapliga studier.
... In the indoor environment, toilet is one of the primary sources of bioaerosol due to flushing events [1,2]. The flow of toilet water can aerosolize stool materials (e.g., bubbling, swirling, and splashing) [3,4]. ...
Article
In the indoor environment, toilet is one of the primary sources of bioaerosol because flushing events can disturb stool materials. Bioaerosol exposure has a significant impact on human health. Therefore, this research focused on systematical investigation of Staphylococcus aureus bioaerosol emission characteristics in an indoor toilet after flushing with time. Then, annual probability of infection and disease burden with time under various ventilation scenarios were determined using a Monte Carlo simulation-based quantitative microbial risk assessment. The results showed that at the initial phase, the highest and lowest bioaerosol concentrations were found in poor and combined ventilation scenarios, respectively. The bioaerosol concentration in natural ventilation scenario was 1.1 times higher than that in mechanical ventilation scenario. However, a decreasing trend was observed after flushing. The adult male's health risks were consistently higher than those of all other exposed persons. However, the maximum and minimum health risks were observed in the poor and combined ventilation scenario, respectively. The health risks in the mechanical ventilation scenario were lower than those in the natural ventilation scenario. However, the health infection risk varied with time: it was unbearable to the U.S. Environmental Protection Agency benchmark at 0 min–15 min after flushing, but it was tolerable after flushing 35 min. Moreover, the disease health burdens were below the World Health Organization benchmark after flushing 20 min to 35 min. This research delivered novel data and provide a guideline for controlling the essential health threats from bioaerosol emissions in various toilet usage scenarios.
... In fact, the aerosol generation with unhealthy outcomes has been studied even before the COVID-19 pandemic (Aithinne et al., 2019). As early as discussed by the classical research of microbiological hazards (Gerba et al., 1975), the aerosol can be generated by toilet plume or flushing which may cause aerosolization (Barker & Jones, 2005;Best et al., 2012;Johnson et al., 2013a;Johnson et al., 2013b;Hamilton et al., 2018) or bioaerosol concentrations (Knowlton et al., 2018). In the process, the emission strength can be strong (Lai et al., 2018), which may promote the transmission of virus if there is any according to the fluid dynamics ). ...
Article
The surprising spread speed of the COVID-19 pandemic creates an urgent need for investigating the transmission chain or transmission pattern of COVID-19 beyond the traditional respiratory channels. This study therefore examines whether human feces and public toilets play a critical role in the transmission of COVID-19. First, it develops a theoretical model that simulates the transmission chain of COVID-19 through public restrooms. Second, it uses stabilized epidemic data from China to empirically examine this theory, conducting an empirical estimation using a two-stage least squares (2SLS) model with appropriate instrumental variables (IVs). This study confirms that the wastewater directly promotes the transmission of COVID-19 within a city. However, the role of garbage in this transmission chain is more indirect in the sense that garbage has a complex relationship with public toilets, and it promotes the transmission of COVID-19 within a city through interaction with public toilets and, hence, human feces. These findings have very strong policy implications in the sense that if we can somehow use the ratio of public toilets as a policy instrument, then we can find a way to minimize the total number of infections in a region. As shown in this study, pushing the ratio of public toilets to the local population in a city to its optimal level would help to reduce the total infection in a region.
... The most significant toilet plume airborne infection risks are likely from viruses (Johnson et al. 2013). Norovirus accounts for most of the nonbacterial gastroenteritis outbreaks worldwide, has a low infectious dose, and can be transmitted by aerosols . ...
Thesis
Source-separated urine is rich in nutrients and provides numerous benefits, including: offsetting energy requirements at wastewater treatment plants; offsetting energy required to produce nitrogen and phosphorus fertilizers; reducing the environmental impact of fertilizer production; and providing an alternative source of fertilizer. Source-separated urine can contain chemical and biological contaminants that need to be managed prior to its use as a fertilizer. Bacteria, viruses, and extracellular nucleic acids, if present in fertilizer, all have the potential to impact the environment being fertilized and consumers of fertilized products. Thus, it is important to understand their behavior and fate in urine and urine-derived products. Information about the fate of chemical and biological contaminants can help inform appropriate treatment technologies that transform urine into useful products while mitigating public and environmental health exposures. This dissertation is focused on microbiological contaminants that may impact public and environmental health. The presence of polyomavirus, a urinary tract virus, was evaluated in stored urine in which urea had been hydrolyzed and the solution pH was around 9.0. Polyomavirus infectivity measured through tissue culture assays was compared to its genome integrity measured through qPCR assays. The virus infectivity was also compared to two surrogate viruses, the bacteriophages MS2 and T3. The infectivity of polyomavirus decreased rapidly in stored urine within 1.1 - 11 hours, compared to surrogate virus infectivity, which remained stable for 3 - 5 weeks. In contrast, polyomavirus genomes were stable for more than 3 weeks despite this loss of infectivity. This led us to look at the fate of extracellular DNA, which may carry antibiotic resistance genes, in hydrolyzed urine. DNA transformation, integrity, and conformation were evaluated using transformation assays, qPCR assays, and gel electrophoresis. Based on filtered and pasteurization experiments, the loss in transformation efficiency correlated to plasmid linearization and appeared to be microbially driven, likely from organisms smaller than 0.22 μm or enzymes larger than 100 kDa. Collectively, these results indicate that the microbial activity of hydrolyzed urine reduced viral infectivity and the transformation of extracellular DNA, decreasing both the risk of exposure to infectious polyomavirus and spread of plasmid- associated antibiotic resistance genes. Finally, urine-diverting toilets, which are used to collect urine separate from other wastes, were compared to conventional flush toilets in terms of virus exposure. Virus-laden droplets were detected at a higher frequency outside the conventional institutional high- flush toilet compared to a urine- diverting toilet, indicating an added benefit of urine- diverting toilets. We conclude that the conditions of hydrolyzed urine reduce the potential risk of polyomaviruses and plasmid- associated antibiotic resistance gene transfer, and that using urine- diverting toilets can reduce one’s exposure to viruses from flushing events. Because storage is a common pretreatment before other fertilizer conversion technologies, this work demonstrates that microbial risks may be low and further advances the possibility of recovering urine for beneficial reuse.
... Next, we considered the infection risk conveyed by virusloaded aerosol particles in the toilet plume that occurs in the toilet space and drainage pipes when cleaning the sewage containing infectious viruses or microorganisms, which has long been indicated as an infection route. 21 As shown in Figure 1, the SARS outbreak at Amoy Gardens in Hong Kong was considered to have occurred because the infectious aerosol particles generated by flushing the stools of an infected person flowed backward through the drainage pipe in the room where the trap seal was broken, and then spread from the indoor environment to the outdoor environment and entered another house by air flow. [22][23][24][25] It has also been reported that SARS-CoV-2 entered and caused infections in a high-rise apartment building in Guangzhou, China, through the drainage stacks and vents from a trap seal where the sealed water had evaporated in the bathroom. ...
Article
Full-text available
It is still undetermined if the main infection route of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that leads to coronavirus disease 2019 (COVID-19), is infection through droplet, contact, or airborne transmission. However, confined spaces with poor ventilation are cited as a risk factor for group outbreaks, and there is growing interest in the effects of intervention through the appropriate operation of air-conditioning and sanitary equipment to reduce the risk of airborne transmission. This study first offers an outline of the characteristics of the novel coronavirus disease and the cluster outbreak case reports that have been clarified until now. Subsequently, we describe the appropriate operating conditions for building equipment that are effective in reducing the risk of infection and also highlight specificities for each building use based on the guidance provided by healthcare institutions and with reference to the standard recommendations by Western academic societies related to building equipment.
... For Indians that are able, they can do their part to avoid the potential fecal-oral transmission of COVID-19 by covering their squat latrines or Western toilets with a lid to avoid potential spread through toilet plume, washing their hands thoroughly and cleaning their toilets with a mild detergent regularly. [12,13] Hygienic washrooms play an important role in the prevention of disease transmission, and it is the authors' hopes that India will take the necessary steps to prevent fecal-oral spread of COVID-19 among its citizens. ...
Article
Full-text available
... The aerosolization of biomatter caused by flushing toilets has long been known to be a potential source of transmission of infectious microorganisms 1,2 . Toilet flushing can generate large quantities of microbe-containing aerosols 3 depending on the design and water pressure or flushing energy of the toilet [4][5][6] . A variety of different pathogens which are found in stagnant water or in waste products (e.g., urine, feces, and vomit) can get dispersed widely via such aerosolization, including the legionella bacterium responsible for causing Legionnaire's disease 7,8 , the Ebola virus 9 , the norovirus which causes severe gastroenteritis (food poisoning) 10,11 , and the Middle East Respiratory Syndrome coronavirus (MERS-CoV) 12 . ...
Article
Full-text available
Aerosolized droplets play a central role in the transmission of various infectious diseases, including Legionnaire's disease, gastroenteritis-causing norovirus, and most recently COVID-19. Respiratory droplets are known to be the most prominent source of transmission for COVID-19; however, alternative routes may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of micro-organisms; thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation. To quantify the extent of aerosolization, we measure the size and number of droplets generated by flushing toilets and urinals in a public restroom. The results indicate that the particular designs tested in the study generate a large number of droplets in the size range 0.3 μ m - 3 μ m , which can reach heights of at least 1.52 m. Covering the toilet reduced aerosol levels but did not eliminate them completely, suggesting that aerosolized droplets escaped through small gaps between the cover and the seat. In addition to consistent increases in aerosol levels immediately after flushing, there was a notable rise in ambient aerosol levels due to the accumulation of droplets from multiple flushes conducted during the tests. This highlights the need for incorporating adequate ventilation in the design and operation of public spaces, which can help prevent aerosol accumulation in high occupancy areas and mitigate the risk of airborne disease transmission.
... As the film stretches, it thins and forms holes that retract and create ligaments of fluid that pinch-off into drops [ Fig. 1 [27]. Similarly, flushing toilets have been shown to generate pathogen-bearing aerosols from bubble rupture [28]. The sloshing of the contaminated toilet water entrains air bubbles that rise to the surface [ Fig. 1(c)]; these bubbles, on rupture, produce an upward jet that can pinch-off into jet drops [ Fig. 1(d)]. ...
Article
Lower respiratory tract infections originate from multiple aerosol sources, varying from droplets erupting from bursting bubbles in a toilet or those produced by human speech. A key component of the aerosol-based infection pathway—from source to potential host—is the survival of the pathogen during aerosolization. Due to their finite-time instability, pinch-off processes occurring during aerosolization have the potential to rapidly accelerate the fluid into focused regions of these droplets, stress objects therein, and if powerful enough, disrupt biological life. However, the extent that a pathogen will be exposed to damaging hydrodynamic stressors during the aerosolization process is unknown. Here we compute the probability that particulates will be exposed to a hydrodynamic stressor during the generation of droplets that range in size from one to 100 microns. For example, particulates in water droplets less than 5 μm have a 50% chance of being subjected to an energy dissipation rate in excess of 1011 W/m3, hydrodynamic stresses in excess of 104 Pa, and strain rates in excess of 107 s−1, values known to damage certain biological cells. Using a combination of numerical simulations and self-similar dynamics, we show how the exposure within a droplet can be generally predicted from its size, surface tension, and density, even across different aerosolization mechanisms. Collectively, these results introduce aerosol agitation as a potential factor in pathogen transmission and implicate the pinch-off singularity flow as setting the distribution of hydrodynamic stressors experienced within the droplet.
... This review focuses only on emissions from the respiratory tract, defined here as the path of respiratory air from deep lungs through the mouth and nose. Nevertheless, other emissions of potentially pathogen-laden particles from the human body (e.g., skin, clothes) -the "personal cloud" effect -can also play critical roles in disease transmission, if deposited in the respiratory tract of a recipient (e.g., Johnson et al., 2013;Meadow et al., 2015;Sherertz et al., 2001;Yamamoto et al., 2015;Yang et al., 2021;You et al., 2013). ...
Preprint
Full-text available
Knowing the physicochemical properties of exhaled droplets and aerosol particles is a prerequisite for a detailed mechanistic understanding and effective prevention of the airborne transmission of infectious human diseases. This article provides a critical review and synthesis of scientific knowledge on the number concentrations, size distributions, composition, mixing state, and related properties of respiratory particles emitted upon breathing, speaking, singing, coughing, and sneezing. We derive and present a parametrization of respiratory particle size distributions based on five lognormal modes related to different origins in the respiratory tract, which can be used to trace and localize the sources infectious particles. This approach may support the medical treatment as well as the risk assessment for aerosol and droplet transmission of infectious diseases. It was applied to analyze which respiratory activities may drive the spread of specific pathogens, such as Mycobacterium tuberculosis, influenza viruses, and SARS-CoV-2 viruses. The results confirm the high relevance of vocalization for the transmission of SARS-CoV-2 as well as the usefulness of face masks, including community, medical, and N95/FFP2 masks, as preventive measures against COVID-19 and other airborne infectious diseases.
... The aerosolization of biomatter caused by flushing toilets has long been known to be a potential source of transmission of infectious microorganisms 1,2 . Toilet flushing can generate large quantities of microbe-containing aerosols 3 depending on the design and water pressure or flushing energy of the toilet [4][5][6] . A variety of different pathogens which are found in stagnant water or in waste products (e.g., urine, feces, and vomit) can get dispersed widely via such aerosolization, including the legionella bacterium responsible for causing Legionnaire's disease 7,8 , the Ebola virus 9 , the norovirus which causes severe gastroenteritis (food poisoning) 10,11 , and the Middle East Respiratory Syndrome coronavirus (MERS-CoV) 12 . ...
Preprint
Full-text available
Aerosolized droplets play a central role in the transmission of various infectious diseases, including Legionnaire's disease, gastroenteritis-causing norovirus, and most recently COVID-19. Respiratory droplets are known to be the most prominent source of transmission for COVID-19, however, alternative routes may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of microorganisms, thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation. To quantify the extent of aerosolization, we measure the size and number of droplets generated by flushing toilets and urinals in a public restroom. The results indicate that the particular designs tested in the study generate a large number of droplets in the size range 0.3$\mu m$ to 3$\mu m$, which can reach heights of at least 1.52m. Covering the toilet reduced aerosol levels but did not eliminate them completely, suggesting that aerosolized droplets escaped through small gaps between the cover and the seat. In addition to consistent increases in aerosol levels immediately after flushing, there was a notable rise in ambient aerosol levels due to the accumulation of droplets from multiple flushes conducted during the tests. This highlights the need for incorporating adequate ventilation in the design and operation of public spaces, which can help prevent aerosol accumulation in high occupancy areas and mitigate the risk of airborne disease transmission.
... Since using the toilet also causes hand disinfection by touching the glasses, the creation of an aerosol after flushing the toilet will also require technical innovations, e.g. the installation of UV-C light for decontamination, and the invitation to wash hands thoroughly after each use of the toilet should be displayed [45,46,47,48,49]. Pets will be left in the car park and personal belongings will remain at home or be stored in a locker. ...
Article
Full-text available
Background The COVID-19 pandemic does not leave the dental practice unattended. In Part 1 the reason why measures should be taken was explored. Objective The objective is to review the measures that can be taken to minimize the risk of tranmission in the dental practice. Data Sources These measures can be classified according to the guidelines of the National Institute for Occupational Safety and Health (NIOSH). Study Selection A qualitative approach explores the applicability of these guidelines to the dental practice. Data Extraction In order to prevent aerosol transmission in the dental practice a large number of changes are needed. It concerns hygiene protocols, organizational protocols and architectural changes, none of which are backed by a legal framework. Conclusion Until a vaccination program is introduced to counter the COVID-19 pandemic in a country, the dental society will need to take measures to prevent aerosol transmission in the dental office. The pyramid of measures according to NIOSH offers a suitable frame to classify all measures. Any legal regulatory intervention could use this framework.
... If aerosolization of fecal matter is important, it can occur by more pedestrian means than a massive aerosolization event in an apartment complex's waste disposal system or cleaning sewage-soaked footwear. Studies have shown that aerosolization of bacteria and other fecal contaminants occurs when toilets are flushed [10,11], though clear implication of this as a route of spread for any disease remains elusive. The evidence does seem strong enough, however, to consider the role of toilets when developing infection control plans for particularly vulnerable populations (e.g., in long term care facilities) or in frequently trafficked areas. ...
... This would also have implications for protocols regarding keeping crew or staff aboard cruise ships after the identification of a COVID-19 outbreak or hospitals with COVID-19 patients (11). Additionally, given the demonstrated ability of high energy flush toilets (the common flushing mechanism) to generate toilet plume (12), could the bathroom be responsible for some part of the high spread within households? ...
... Shared bathrooms in hospitals, rehabilitation centers, or assisted living facilities are used by patients who might be infected, thus making them a likely source of indoor cross-contamination (Best et al. 2012. The pathogen-spreading potential of toilet flushes was investigated in toilets seeded with microorganisms that were later recovered from surfaces and in the air after flushing (Darlow & Bale 1959, Johnson et al. 2013b). The organisms in the bowl could not be fully cleared even after repeated flushing (Gerba et al. 1975), and the droplets produced by flushing harbored the organisms that were used for seeding, which remained airborne and viable. ...
Article
For an infectious disease such as the coronavirus disease 2019 (COVID-19) to spread, contact needs to be established between an infected host and a susceptible one. In a range of populations and infectious diseases, peer-to-peer contact modes involve complex interactions of a pathogen with a fluid phase, such as isolated complex fluid droplets or a multiphase cloud of droplets. This is true for exhalations including coughs or sneezes in humans and animals, bursting bubbles leading to micron-sized droplets in a range of indoor and outdoor settings, or impacting raindrops and airborne pathogens in foliar diseases transferring pathogens from water to air via splashes. Our mechanistic understanding of how pathogens actually transfer from one host or reservoir to the next remains woefully limited, with the global consequences that we are all experiencing with the ongoing COVID-19 pandemic. This review discusses the emergent area of the fluid dynamics of disease transmission. It highlights a new frontier and the rich multiscale fluid physics, from interfacial to multiphase and complex flows, that govern contact between an infected source and a susceptible target in a range of diseases. Expected final online publication date for the Annual Review of Fluid Mechanics, Volume 53 is January 6, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... It is worth recalling that vomiting or flushing the toilet can generate the aerosols causing subsequent airborne transmission (Johnson, Mead, Lynch, & Hirst, 2013;Knowlton et al., 2018). Spreading the virus through aerosolization and vaporization of fecal waste water has been demonstrated for adenoviruses and torque teno virus as they have already been detected in aerosols surrounding toilets (Verani, Bigazzi, & Carducci, 2014). ...
Article
Full-text available
Background: COVID-19 is a pandemic disease that has paralyzed social life and the economy around the world since the end of 2019, and which has so far killed nearly 300,000 people. The rapidity of its spread and the lack of detailed research on the course and methods of transmission significantly impede both its eradication and prevention. Scope and approach: Due to the high transmission rate and fatality resulting from COVID-19 disease, the paper focus on analyzing the current state of knowledge about SARS-CoV-2 as well as its potential connection with food as a source of pathogen and infection. Key findings and conclusions: There is currently no evidence (scientific publications, WHO, EFSA etc.) that COVID-19 disease can spread directly through food and the human digestive system. However, according to the hypothesis regarding the primary transmission of the virus, the source of which was food of animal origin (meat of wild animals), as well as the fact that food is a basic necessity for humans, it is worth emphasizing that food can, if not directly can be a carrier of the virus. Particular attention should be paid to this indirect pathway when considering the potential for the spread of an epidemic and the development of prevention principles.
... CoV-2 from stool samples (non-diarrhoea) from two patients [5]. This is of particular interest since various studies have shown the production of bioaerosols during toilet flushing [6]. That is significant since new data shows that airborne transmission plays a major role for the spread of SARS-CoV-2 [7]. ...
Article
Full-text available
The current literature strongly indicates that SARS-CoV-2 infections in the gut have short- and long-term effects. The short-term effects are gastrointestinal symptoms and in about 50% of the patients, viral shedding in the stool occurs. Toilet flushing can create infectious bioaerosols that are a potential risk factor for oral/nasalfaecal transmission of SARS-CoV-2. Cleaning procedures of toilets in hospitals, care facilities, schools, nurseries, workplaces, restaurants, trains, busses, airplanes, and public spaces will need to be looked at and perhaps improved. Recent studies also indicate that infections with SARS-CoV-2 lead to changes in the human gut microbiome and could lead to long term effects. This is an opinion paper. Journal: Infectious Diseases and Therapeutics
... Facility A did note a housekeeping staffing shortage during 2018. Unrecognized colonization and missed opportunities in environmental cleaning may have played a role in the transmission of gastrointestinal flora from the source patient to other patients on the same unit in Facility A. Unrecognized colonization and a shared bathroom may have led to transmission from the source patient to the roommate at Facility B. It has been shown that toilet flushing generates aerosolized bacteria that can land on nearby surfaces or drift in air currents to land on surfaces further away, which can contribute to the direct and/or indirect transmission of gastrointestinal flora (Barker and Jones, 2005;Johnson D. L. et al., 2013;. As environmental screening was not done in the course of this investigation, it is impossible to determine if horizontal transfer of the plasmid harboring bla KPC−2 may have occurred in the environment at Facility A and/or B, or within a patient, or both. ...
Article
Full-text available
Carbapenemase-producing Enterobacteriaceae are a major threat to global public health. Klebsiella pneumoniae carbapenemase (KPC) is the most commonly identified carbapenemase in the United States and is frequently found on mobile genetic elements including plasmids, which can be horizontally transmitted between bacteria of the same or different species. Here we describe the results of an epidemiological investigation of KPC-producing bacteria at two healthcare facilities. Using a combination of short-read and long-read whole-genome sequencing, we identified an identical 44 kilobase plasmid carrying the blaKPC–2 gene in four bacterial isolates belonging to three different species (Citrobacter freundii, Klebsiella pneumoniae, and Escherichia coli). The isolates in this investigation were collected from patients who were epidemiologically linked in a region in which KPC was uncommon, suggesting that the antibiotic resistance plasmid was transmitted between these bacterial species. This investigation highlights the importance of long-read sequencing in investigating the relatedness of bacterial plasmids, and in elucidating potential plasmid-mediated outbreaks caused by antibiotic resistant bacteria.
... Numerous research studies have shown that the flushing of toilets can generate aerosols that could lead to the transmission of pathogens (Aithinne et al. 2019;Johnson et al. 2013). However, in the case of SARS-CoV-2, the potential contribution of this route of transmission is unclear. ...
... coli), Shigella sonnei, Streptococcus, Staphylococcus, Salmonella, Yersinia and viruses such as norovirus, rotavirus, adenovirus, Torque teno virus spread from toilet surfaces (Gerhardts et al. 2012;Greed 2006;Mendes and Lynch 1976;Sassi et al. 2018) and can result in several serious health issues. Flushing of toilets or cleaning lavatories using pressurized water jet streams can also result in aerosolization of the above mentioned bacteria and viruses which can cause transmission of infectious diseases such as Severe Acute Respiratory Syndrome (SARS) (Gerhardts et al. 2012;Greed 2006;Mendes and Lynch 1976;Johnson et al. 2013;Hamilton et al. 2018). ...
Article
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The purpose of this article is twofold, one is to provide a brief review on various lavatory cleaning devices while the other is to study the feasibility of using these devices in public toilets in developing countries. The article presents a literature review on various lavatory cleaning devices, focusing on various designs available as patent documents and commercially available toilet cleaning robots. The issues that prevent these devices from being deployed in multi-lavatory public toilet complexes in developing countries are discussed. Design considerations of a simple, cost-effective, semi-automated lavatory cleaning robot that may serve as a solution to these issues are also covered in this article.
... In fact, human expiratory activities (coughing, sneezing, speaking and singing, but also just breathing) release particles in a wide range of size, from 1 to 2000 µm, with the majority of them between 2 and 100 µm [22]. Moreover, the production of droplets and aerosol from the toilet flow or the sewage treatment processes was demonstrated also for respiratory viruses [23]. The droplet/aerosol dispersion has been widely studied, so that pictures of the mouth "cloud" have been captured firstly by photos with incident light [24] and then by the sophisticated new recording graphic processing systems [25,26], and numerous experiments have been carried out to study the dynamic of airborne particles [27]. ...
Article
Full-text available
Besides the predominant ways of transmission of SARS-CoV-2 (namely, contacts and large droplets) the airborne one is increasingly taken into consideration as a result of latest research findings. Nevertheless, this possibility has been already suggested by previous studies on other coronaviruses including SARS-CoV and MERS-CoV. To describe the state of the art of coronaviruses and airborne transmission, a systematic review was carried out using the PRISMA methodology. Overall, 64 papers were selected and classified into three main groups: laboratory experiments (12 papers), air monitoring (22) and epidemiological and airflow model studies (30). The airborne transmission of SARS-CoV-2 is suggested by the studies of the three groups, but none has yet obtained complete evidence. The sampling and detection methods have not been validated, therefore monitoring results are a�ected by a possible underestimation. Then, epidemiological investigations only hypothesize the airborne transmission as a possible explanation for some illness cases, but without estimating its attributable risk. Nevertheless, while waiting for more evidence, it is urgent to base advice on preventive measures, such as the use of masks, safe distancing and air ventilation, on the precautionary principle.
... For Indians that are able, they can do their part to avoid the potential fecal-oral transmission of COVID-19 by covering their squat latrines or Western toilets with a lid to avoid potential spread through toilet plume, washing their hands thoroughly and cleaning their toilets with a mild detergent regularly. [12,13] Hygienic washrooms play an important role in the prevention of disease transmission, and it is the authors' hopes that India will take the necessary steps to prevent fecal-oral spread of COVID-19 among its citizens. ...
... The latter can additionally be contaminated by transfers of microorganisms to the air during flushing. 51,52 Buses and other means of public transportation 53 (Figure 1c) also involve many individuals sharing confined air in small spaces as well as frequent hand contact with small area surfaces such as handrails. Although often involving larger volumes, the work environment in shared offices ( Figure 1d) and workshops can foster virus transmission as well because people spend long working hours inside of them. ...
Article
Full-text available
We advocate the widespread use of UV-C light as a short-term, easily deployable, and affordable way to limit virus spread in the current SARS-CoV-2 pandemic. Radical social distancing with the associated shutdown of schools, restaurants, sport clubs, workplaces, and traveling has been shown to be effective in reducing virus spread, but its economic and social costs are unsustainable in the medium term. Simple measures like frequent handwashing, facial masks, and other physical barriers are being commonly adopted to prevent virus transmission. However, their efficacy may be limited, particularly in shared indoor spaces, where, in addition to airborne transmission, elements with small surface areas such as elevator buttons, door handles, and handrails are frequently used and can also mediate transmission. We argue that additional measures are necessary to reduce virus transmission when people resume attending schools and jobs that require proximity or some degree of physical contact. Among the available alternatives, UV-C light satisfies the requirements of rapid, widespread, and economically viable deployment. Its implementation is only limited by current production capacities, an increase of which requires swift intervention by industry and authorities.
... Wherever might be the primary source of contamination, public toilets are likely foci for contracting ESBL-producing bacteria similar to other pathogens. Earlier studies have identified public toilets as sources of possible spread of infections within the community especially during disease outbreaks (Johnson et al., 2013;Suen et al., 2019). The use of public toilets within the community could be a risk factor for insidious transmission of ESBL-producing bacteria to unsuspecting people (Dayan, 2004). ...
Article
Full-text available
Increasing reports of the pandemic nature of extended spectrum β-lactamase (ESBL) producing bacteria in clinical infections called for more surveillance to identify possible sources of infection. This study examined the dissemination of ESBL producing Enterobacteriaceae in hospital and public toilet facilities in Abeokuta. Swab samples were collected from toilet seats, door handles, toilet bowls and flush handles. Detection of ESBL producing isolates was done using double disc test. Presence of ESBL gene was done using multiplex PCR. Overall, ESBL-producing bacteria was detected in 44 (27.5%) out of 160 samples. ESBL-producing bacteria were detected at significantly higher rate )p<0.001) in hospital toilets than in community toilets. Isolates were identified as Klebsiella pneumoniae (n=25), Klebsiella oxytoca (n=2), Citrobacter freundii (n=6), Citrobacter youngae (n=3), Escherichia coli (n=5), Enterobacter cloacae (n=2) and Enterobacter kobei (n=1). . Analysis for the presence of ESBL gene showed that all the isolates harboured the blaCTX-M- gene while blaTEM and blaSHV were detected in six and two isolates respectively. All the ESBL-producing isolates demonstrated resistance to at least three different classes of antimicrobials. The study showed that public toilets could serve as sources for nosocomial and community transmission of ESBL-producing bacteria in the environment.
Article
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Aerosols can transmit infectious diseases including SARS-CoV-2, influenza and norovirus. Flushed toilets emit aerosols that spread pathogens contained in feces, but little is known about the spatiotemporal evolution of these plumes or the velocity fields that transport them. Using laser light to illuminate ejected aerosols we quantify the kinematics of plumes emanating from a commercial flushometer-type toilet, and use the motion of aerosol particles to compute velocity fields of the associated flow. The toilet flush produces a strong chaotic jet with velocities exceeding 2 m/s; this jet transports aerosols to heights reaching 1.5 m within 8 seconds of initiating a flush. Quantifying toilet plumes and associated flow velocities provides a foundation for future design strategies to mitigate plume formation or to disinfect pathogens within it.
Article
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In this study, based on the numerical simulation , we investigated aerosol pollution diffusion in residential bathroom with exhaust vents at different positions and different ventilation methods. The results show that setting an air outlet under the side wall next to the toilet can discharge aerosol pollutants in time , which not only shortens the diffusion path of aerosol pollutants , but also optimizes the air organization form. The dry and wet separation of the toilet area and the wash area separated by a physical partition adopts the principle of "screen" , which effectively blocks the transmission path of aerosol pollutants.
Article
Background The spread of some respiratory and gastro-intestinal infections has been linked to the exposure to infectious bioaerosols released after toilet flushing. This represents a health hazard and infection risk for immunocompromised patients, health workers and the public, particularly within the healthcare and hospitality settings. This systematic review provides current knowledge and identifies gaps in the evidence regarding toilet plume bioaerosols and the potential contributing role in spreading infections in healthcare and hospitality settings. Methods The PRISMA guidelines were used. Searches were run in PubMed, Scopus, and Google Scholar from 1950 to 30th June 2021. Searches of global and regional reports and updates from relevant international and governmental organisations were also conducted. Results and Conclusion The search yielded 712 results, and 37 studies were finally selected for this review. There is a lack of national and international bioaerosol sampling and exposure standards for healthcare and hospitality settings. Toilet plume bioaerosols are complex in nature, thus, measured bioaerosol concentrations in these settings depend on many variables and may differ for every pathogen responsible for a particular infectious disease. The contact and airborne transmission risks posed by toilet plume bioaerosols also remain unquantified. They are an important pathway that can increase the exposure to enteric and airborne pathogens. Hence, quantitative risk assessment and related research are needed to investigate these transmission risks.
Article
Lavatory use on commercial aircraft may present a risk of contagion, especially on long-haul flights. Flushing the toilet can induce a strong sweeping flow, which generates aerosols in the toilet bowl and also resuspends deposited particles from lavatory surfaces. Currently, the generation of aerosols, the flushing-induced airflow, and the potential of airborne particle exposure for a lavatory user are unclear. This investigation performed in-flight tests to measure the particle concentrations in the toilet bowl, near the floor, and in the breathing zone. A lavatory mockup was constructed in a laboratory for visualization of the airflow and measurement of airflow speeds. After the similarity in particle generation between the in-flight test and mockup model had been verified, the residual ratio of the generated aerosols in the toilet bowl after flushing was determined. Then the total number of generated aerosols in the toilet bowl of a commercial aircraft was inferred. In addition, the effects of the drainage pressure and rinse water pressure on the particle concentrations and spectrum were measured and evaluated. The results revealed that the total number of aerosols larger than 0.3 μm generated by the flushing of a toilet on a typical aircraft was 8498 ± 1,918, of which the submicron particles comprised 92%. A higher drainage pressure or a lower rinse water pressure resulted in a lower monitored aerosol concentration. The concentration in the breathing zone with an open toilet lid was clearly higher than that with a closed toilet lid, which should be given careful attention.
Article
Full-text available
The lavatory is a fertile area for the transmission of infectious disease through bioaerosols between its users. In this study, we built a generic compact lavatory model with a vacuum toilet, and computational fluid dynamics (CFD) is used to evaluate the effects of ventilation and user behaviors on the airflow patterns, and the resulting fates of bioaerosols. Fecal aerosols are readily released into the lavatory during toilet flush. Their concentration rapidly decays in the first 20 s after flushing by deposition or dilution. It takes about 315 s to 348 s for fine bioaerosols (<10 µm in diameter) to decrease to 5% of the initial concentration, while it takes 50 and 100 µm bioaerosols approximately 11 and <1 s, respectively, to completely deposit. The most contaminated surfaces by aerosol deposition include the toilet seat, the bowl, and the nearby walls. The 10 µm aerosols tend to deposit on horizontal surfaces, while the 50 and 100 µm bioaerosols almost always deposit on the bowl. In the presence of a standing thermal manikin, the rising thermal plume alters the flow field and more bioaerosols are carried out from the toilet; a large fraction of aerosols deposit on the manikin’s legs. The respiratory droplets generated by a seated coughing manikin tend to deposit on the floor, legs, and feet of the manikin. In summary, this study reveals the bioaerosol dilution time and the easily contaminated surfaces in a compact lavatory, which will aid the development of control measures against infectious diseases.
Article
Contact surfaces within shared sanitation facilities could lead to disease transmission due to contamination. In this study, we applied metagenomics, by targeting the 16S rRNA gene region using illumina sequencing to determine the common bacterial communities on key contact surfaces in shared sanitation facilities within a metropolitan municipality area. The common bacterial phyla identified on these surfaces were Actinobacteria, Firmicutes, Proteobacteria, and Bacteriodetes, with average counts up to 12 Log10 and a prevalence of 100% for each of these phyla. Known diarrhoeal pathogens like, Salmonella enterica, Bacillus cereus, Campylobacter jejuni, Campylobacter coli, Yersinia pestis, Yersinia pseudotuberculosis, Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus were detected on almost all surfaces. Cistern handles, tap handles and toilet seats had the highest number of potentially pathogenic bacteria, such as S. enterica. Additionally, uncommon and very rarely pathogenic bacteria such as Cedeceae neteri, Enterobacter hormaechei, Klebsiella michiganensis, Pluralibacter gergoviae, Kosakonia cowanii and Raoutella ornithinolyitca were also detected. Many of these can be considered as environmental commensals. These results show that contact surfaces within shared sanitation facilities could have been contaminated with faecal matter as well as soil. In conclusion, being the first study to apply metagenomics in profiling bacterial communities on contact surfaces in shared sanitation facilities in South Africa, this study shows the potential of disease transmission via the use of these shared facilities. Additionally, the results also show the application of 16S rRNA-based metagenomics in determining the potential role of shared sanitation in disease transmission.
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The hospital water environment, including the wastewater drainage system, is increasingly reported as a potential reservoir for carbapenemase-producing Enterobacterales (CPE). We investigated a persistent outbreak of OXA-48 CPE (primarily Citrobacter freundii ) in a haematological ward of a French teaching hospital by epidemiological, microbiological and environmental methods. Between January 2016 and June 2019, we detected 37 new OXA-48 CPE-colonised and/or ‑infected patients in the haematological ward. In October 2017, a unit dedicated to CPE-colonised and/or ‑infected patients was created. Eleven additional sporadic acquisitions were identified after this date without any obvious epidemiological link between patients, except in one case. Environmental investigations of the haematological ward (June–August 2018) identified seven of 74 toilets and one of 39 drains positive for OXA-48 CPE (seven C. freundii , one Enterobacter sakazakii , one Escherichia coli ). Whole genome comparisons identified a clonal dissemination of OXA-48-producing C. freundii from the hospital environment to patients. In addition to strict routine infection control measures, an intensive cleaning programme was performed (descaling and bleaching) and all toilet bowls and tanks were changed. These additional measures helped to contain the outbreak. This study highlights that toilets can be a possible source of transmission of OXA-48 CPE.
Article
Background Toilet surfaces are contaminated with pathogens, and they may be a vector for disease transmission. In this study, we investigated the efficacy of an automated 222-nm ultraviolet C (UVC) disinfection device “Care222™,” with a motion sensor, for removing bacterial contamination in a shared bathroom. Methods Two automated UVC devices, deactivated by motion sensors, were mounted on the ceiling of two bathrooms; the emission window of the UVC device was covered in the non-treated bathroom. After irradiation, samples were collected from five surfaces at four time points/day for 5 days, and colony-forming units (CFUs) of aerobic bacteria (AB) were determined. The irradiation time was also measured. Results UVC source deactivation time did not significantly differ between the bathrooms. There was a significant difference in the total AB CFUs between the treated and non-treated bathrooms. In the treated bathroom, the CFUs of AB of the toilet seat, control panel of the electric toilet seat, and top of the toilet paper holder were significantly lower than those of the control. The CFUs of AB at 9:00, 15:00, and 18:00 h in the treated bathroom were significantly lower than those of the control. Conclusions The automated 222-nm UVC disinfection device with a motion sensor significantly reduced AB surface contamination of a shared bathroom.
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The highly contagious coronavirus disease 2019 (COVID-19) pandemic that began in late 2019 has greatly affected education globally, especially for learning skills that require human contact and constant practice in order to achieve competency. Similar to the rest of the world, the closure of theaters and suspension of school activities in Singapore have particularly impacted the dance and performing arts academies. As economies around the world gradually open up, performance-based colleges must find ways to provide a safe and sustainable environment while adhering to public health guidelines during a pandemic. Implementing safety protocols in the campus and studio can minimize disease transmission. This article presents measures and guidelines to help minimize the risk of viral spread, including using a blended model of virtual home-based and face-to-face training with faculty, in order to ensure continued adequate pre-professional dance education. The challenges of providing a blended model of education are also addressed.
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The objective of this research was to evaluate the performance of a greywater treatment 13 plant, composed of an upflow anaerobic filter followed by a vertical constructed wetland, and 14 to assess the microbial risk resulting from the non-potable reuse of its effluent. The microbial 15 risk posed by selected pathogens (rotavirus, Campylobacter spp. and Cryptosporidium spp.), 16 through the ingestion of aerosols during toilet flushing or garden irrigation, was investigated 17 using the QMRA approach. According to the Brazilian water reuse technical standards, the 18 monitored greywater treatment plant was not able to consistently produce reclaimed water 19 with satisfactory quality for reuse. Moreover, although the treatment plant produced an 20 effluent that achieved the USEPA recommended level of 10-4pppy for the risk of infection 21 posed by Campylobacter spp. and Cryptosporidium spp., the risk posed by rotavirus was above 22 this threshold. The monitoring data and the QMRA outcomes showed that a post-treatment, 23 including sand filtration and chlorination, was essential to produce reclaimed water 24 presenting a risk of infection below 10-4 for all evaluated target pathogens. The QMRA was 25 very useful to evaluate and compare different levels of treatment applied to greywater reuse, 26 based on similar assumptions. It was also concluded that the use of E. coli does not appear to 27 be appropriate to assess the risk of infection in greywater reuse systems.
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Introduction Non-pharmaceutical measures to facilitate a response to the COVID-19 pandemic, a disease caused by novel coronavirus SARS-CoV-2, are urgently needed. Using the World Health Organization (WHO) health emergency and disaster risk management (health-EDRM) framework, behavioural measures for droplet-borne communicable diseases and their enabling and limiting factors at various implementation levels were evaluated. Sources of data Keyword search was conducted in PubMed, Google Scholar, Embase, Medline, Science Direct, WHO and CDC online publication databases. Using the Oxford Centre for Evidence-Based Medicine review criteria, 10 bottom-up, non-pharmaceutical prevention measures from 104 English-language articles, which published between January 2000 and May 2020, were identified and examined. Areas of agreement Evidence-guided behavioural measures against transmission of COVID-19 in global at-risk communities were identified, including regular handwashing, wearing face masks and avoiding crowds and gatherings. Areas of concern Strong evidence-based systematic behavioural studies for COVID-19 prevention are lacking. Growing points Very limited research publications are available for non-pharmaceutical measures to facilitate pandemic response. Areas timely for research Research with strong implementation feasibility that targets resource-poor settings with low baseline health-EDRM capacity is urgently needed.
Article
Background Carbapenemase-producing Enterobacterales (CPE) have rapidly emerged in Europe, being responsible for nosocomial outbreaks. Aim Following an outbreak in the burn unit of Ghent University Hospital, we investigated whether CPE can spread between toilets through drain water and therefrom be transmitted to patients. Methods In 2017, the burn centre of our hospital experienced an outbreak of OXA-48 producing Klebsiella pneumoniae that affected five patients staying in three different rooms. Environmental samples were collected from the sink, shower, shower stretcher, handrail of the bed, nursing carts, toilets and drain water to explore a common source. Whole-genome sequencing and phylogenetic analysis was performed on K. pneumoniae outbreak isolates and two random K. pneumoniae isolates. Findings OXA-48 producing K. pneumoniae was detected in toilet water in 4/6 rooms and drain water between two rooms. The strain persisted in 2/6 rooms after two months of daily disinfection with bleach. All outbreak isolates belonged to sequence type (ST) 15 and showed isogenicity (<15 allele differences). This suggests that the strain may have spread between rooms by drain water. Unexpectedly, one random isolate obtained from a patient who became colonized whilst residing at the geriatric ward clustered with the outbreak isolates, suggesting the outbreak to be larger than expected. Daily application of bleach tended to be superior to acetic acid to disinfect toilet water, however, disinfection did not completely prevent the presence of carbapenemase-producing K. pneumoniae in toilet water. Conclusion Toilet drain water may be a potential source of hospital room-to-room transmission of carbapenemase-producing K. pneumoniae.
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The Venezuelan Society of Childcare and Pediatrics (SVPP) always at the forefront and thinking about welfare of the child population and the continuing medical education of our Pediatricians and all other health professionals including to students in health-related careers, gathered to a specialized working group, to carry out a second review of relevant literature related to the COVID-19 pandemic, considering the systemic involvement of the SARS-CoV-2 in order to produce a second supplement of Venezuelan Archives of Childcare and Pediatrics (AVPP) as a practical guide for the purpose provide up-to-date information.
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Background: On April 15 and April 17, 2009, novel swine-origin influenza A (H1N1) virus (S-OIV) was identified in specimens obtained from two epidemiologically unlinked patients in the United States. The same strain of the virus was identified in Mexico, Canada, and elsewhere. We describe 642 confirmed cases of human S-OIV infection identified from the rapidly evolving U.S. outbreak. Methods: Enhanced surveillance was implemented in the United States for human infection with influenza A viruses that could not be subtyped. Specimens were sent to the Centers for Disease Control and Prevention for real-time reverse-transcriptase-polymerase-chain-reaction confirmatory testing for S-OIV. Results: From April 15 through May 5, a total of 642 confirmed cases of S-OIV infection were identified in 41 states. The ages of patients ranged from 3 months to 81 years; 60% of patients were 18 years of age or younger. Of patients with available data, 18% had recently traveled to Mexico, and 16% were identified from school outbreaks of S-OIV infection. The most common presenting symptoms were fever (94% of patients), cough (92%), and sore throat (66%); 25% of patients had diarrhea, and 25% had vomiting. Of the 399 patients for whom hospitalization status was known, 36 (9%) required hospitalization. Of 22 hospitalized patients with available data, 12 had characteristics that conferred an increased risk of severe seasonal influenza, 11 had pneumonia, 8 required admission to an intensive care unit, 4 had respiratory failure, and 2 died. The S-OIV was determined to have a unique genome composition that had not been identified previously. Conclusions: A novel swine-origin influenza A virus was identified as the cause of outbreaks of febrile respiratory infection ranging from self-limited to severe illness. It is likely that the number of confirmed cases underestimates the number of cases that have occurred.
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We describe an investigation of a norovirus gastroenteritis outbreak aboard a cruise ship affecting 6 consecutive cruises and the use of sequence analysis to determine modes of virus transmission. Noroviruses (NoV), are the most common cause of infectious acute gastroenteritis and are transmitted feco-orally through food and water, directly from person to person and by environmental contamination (1). These viruses are often responsible for protracted outbreaks in closed settings, such as cruise ships, nursing homes, and hospitals (2,3).
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Current data on the risk of transmission of 2009 H1N1 Influenza in public transportation systems (e.g., public trains, busses, airplanes) are conflicting. The main transmission route of this virus is thought to be via droplets, but airborne transmission has not been completely ruled out. This is a contact tracing investigation of a young woman subsequently diagnosed with the 2009 H1N1 Influenza virus who was symptomatic during a long-distance bus trip from Spain to Switzerland. Fever and cough had begun 24 h earlier, 2 h before she stepped onto a bus for a long-distance trip. After the 2009 H1N1 virus had been confirmed in the patient, the other bus travellers were contacted by telephone on day 7 and 10 after the bus trip. Of the 72 individuals travelling on the bus with the H1N1-infected young woman, 52 (72%) could be contacted. Only one of these 52 developed fever, with onset of symptoms 3 days after the bus trip, and rRT-PCR analysis of the nasopharyngeal swab showed the infection to be caused by the 2009 H1N1 virus. One other person complained of coughing 1 day after the bus trip, but without fever, and no further investigation was carried out. All other passengers remained without fever, coughing, or arthralgia. The risk of transmission was calculated as 1.96% (95% confidence interval 0-5.76%). The transmission rate of 2009 H1N1 Influenza was low on a long-distance bus trip.
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The relative importance of the aerosol transmission route for influenza remains contentious. To determine the potential for influenza to spread via the aerosol route, we measured the size distribution of airborne influenza A viruses. We collected size-segregated aerosol samples during the 2009-2010 flu season in a health centre, a day-care facility and onboard aeroplanes. Filter extracts were analysed using quantitative reverse transcriptase polymerase chain reaction. Half of the 16 samples were positive, and their total virus concentrations ranged from 5800 to 37,000 genome copies m(-3). On average, 64 per cent of the viral genome copies were associated with fine particles smaller than 2.5 µm, which can remain suspended for hours. Modelling of virus concentrations indoors suggested a source strength of 1.6±1.2×10(5) genome copies m(-3) air h(-1) and a deposition flux onto surfaces of 13±7 genome copies m(-2) h(-1) by Brownian motion. Over 1 hour, the inhalation dose was estimated to be 30±18 median tissue culture infectious dose (TCID50), adequate to induce infection. These results provide quantitative support for the idea that the aerosol route could be an important mode of influenza transmission.
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Characterizing household transmission of the 2009 pandemic A/H1N1 influenza virus (pH1N1) is critical for the design of effective public health measures to mitigate spread. Our objectives were to estimate the secondary attack rates (SARs), the proportion of asymptomatic infections, and risk factors for pH1N1 transmission within households on the basis of active clinical follow-up and laboratory-confirmed outcomes. We conducted a prospective observational study during the period May-July 2009 (ie, during the first wave of the pH1N1 pandemic) in Quebec City, Canada. We assessed pH1N1 transmission in 42 households (including 43 primary case patients and 119 contacts). Clinical data were prospectively collected during serial household visits. Secondary case patients were identified by clinical criteria and laboratory diagnostic tests, including serological and molecular methods. We identified 53 laboratory-confirmed secondary case patients with pH1N1 virus infection, for an SAR of 45% (95% confidence interval [CI], 35.6%-53.5%). Thirty-four (81%) of the households had ≥1 confirmed secondary case patient. The mean serial interval between onset of primary and confirmed secondary cases was 3.9 days (median interval, 3 days). Influenza-like illness (fever and cough or sore throat) developed in 29% (95% CI, 20.5%-36.7%) of household contacts. Five (9.4%) of secondary case patients were asymptomatic. Young children (<7 years of age) were at highest risk of developing laboratory-confirmed influenza-like illness. Primary case patients with both diarrhea and vomiting were the most likely to transmit pH1N1. Household transmission of pH1N1 may be substantially greater than previously estimated, especially in association with clinical presentations that include gastrointestinal complaints. Approximately 10% of pH1N1 infections acquired in the household may be asymptomatic.
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In immunocompromised patients, influenza infection may progress to prolonged viral shedding from the respiratory tract despite antiviral therapy. We describe chronic influenza A virus infection in an immunocompromised child who had prolonged shedding of culturable influenza virus in stool.
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To assess the risk of transmission of pandemic A/H1N1 2009 influenza (pandemic A/H1N1) from an infected high school group to other passengers on an airline flight and the effectiveness of screening and follow-up of exposed passengers. Retrospective cohort investigation using a questionnaire administered to passengers and laboratory investigation of those with symptoms. Auckland, New Zealand, with national and international follow-up of passengers. Passengers seated in the rear section of a Boeing 747-400 long haul flight that arrived on 25 April 2009, including a group of 24 students and teachers and 97 (out of 102) other passengers in the same section of the plane who agreed to be interviewed. Laboratory confirmed pandemic A/H1N1 infection in susceptible passengers within 3.2 days of arrival; sensitivity and specificity of influenza symptoms for confirmed infection; and completeness and timeliness of contact tracing. Nine members of the school group were laboratory confirmed cases of pandemic A/H1N1 infection and had symptoms during the flight. Two other passengers developed confirmed pandemic A/H1N1 infection, 12 and 48 hours after the flight. They reported no other potential sources of infection. Their seating was within two rows of infected passengers, implying a risk of infection of about 3.5% for the 57 passengers in those rows. All but one of the confirmed pandemic A/H1N1 infected travellers reported cough, but more complex definitions of influenza cases had relatively low sensitivity. Rigorous follow-up by public health workers located 93% of passengers, but only 52% were contacted within 72 hours of arrival. A low but measurable risk of transmission of pandemic A/H1N1 exists during modern commercial air travel. This risk is concentrated close to infected passengers with symptoms. Follow-up and screening of exposed passengers is slow and difficult once they have left the airport.
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Pulmonary tuberculosis diagnosis is difficult when patients cannot produce sputum. Most sputum is swallowed, and tuberculosis DNA can survive intestinal transit. We therefore evaluated molecular testing of stool specimens for detecting tuberculosis originating from the lungs. Paired stool and sputum samples (n=159) were collected from 89 patients with pulmonary tuberculosis. Control stool samples (n=47) were collected from patients without tuberculosis symptoms. Two techniques for DNA extraction from stool samples were compared, and the diagnostic accuracy of the PCR in stool was compared with the accuracy of sputum testing by PCR, microscopy, and culture. A heminested IS6110-PCR was used for tuberculosis detection, and IS6110-PCR-positive stool samples then underwent rifampin sensitivity testing by universal heteroduplex generator PCR (heteroduplex-PCR) assay. For newly diagnosed pulmonary tuberculosis patients, stool IS6110-PCR had 86% sensitivity and 100% specificity compared with results obtained by sputum culture, and stool PCR had similar sensitivities for HIV-positive and HIV-negative patients (P=0.3). DNA extraction with commercially available spin columns yielded greater stool PCR sensitivity than DNA extraction with the in-house Chelex technique (P=0.007). Stool heteroduplex-PCR had 98% agreement with the sputum culture determinations of rifampin resistance and multidrug resistance. Tuberculosis detection and drug susceptibility testing by stool PCR took 1 to 2 days compared with an average of 9 weeks to obain those results by traditional culture-based testing. Stool PCR was more sensitive than sputum microscopy and remained positive for most patients for more than 1 week of treatment. In conclusion, stool PCR is a sensitive, specific, and rapid technique for the diagnosis and drug susceptibility testing of pulmonary tuberculosis and should be considered when sputum samples are unavailable.
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The clinical picture in severe cases of pandemic (H1N1) 2009 influenza is markedly different from the disease pattern seen during epidemics of seasonal influenza, in that many of those affected were previously healthy young people. Current predictions estimate that, during a pandemic wave, 12-30% of the population will develop clinical influenza (compared with 5-15% for seasonal influenza) with 4% of those patients requiring hospital admissions and one in five requiring critical care. This review covers the background, clinical presentation, diagnosis, and treatment. The role of immunization and antiviral drugs is discussed. Experience from the first wave of pandemic (H1N1) 2009 influenza suggests that a number of infected patients become critically ill and require intensive care admission. These patients rapidly develop severe progressive respiratory failure which is often associated with failure of other organs, or marked worsening of underlying airways disease. The critical care management of these patients and the implications for resources is reviewed. Guidance from a range of bodies has been produced in a relatively short period of time in response to pandemic (H1N1) 2009 influenza. Disease severity has the potential to change, especially if there is virus mutation. Clinicians must be prepared for the unexpected and continue to share their experiences to maximize patient outcomes.
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As of June 11, 2009, a total of 17,855 probable or confirmed cases of 2009 pandemic influenza A (H1N1) had been reported in the United States. Risk factors for transmission remain largely uncharacterized. We characterize the risk factors and describe the transmission of the virus within households. Probable and confirmed cases of infection with the 2009 H1N1 virus in the United States were reported to the Centers for Disease Control and Prevention with the use of a standardized case form. We investigated transmission of infection in 216 households--including 216 index patients and their 600 household contacts--in which the index patient was the first case patient and complete information on symptoms and age was available for all household members. An acute respiratory illness developed in 78 of 600 household contacts (13%). In 156 households (72% of the 216 households), an acute respiratory illness developed in none of the household contacts; in 46 households (21%), illness developed in one contact; and in 14 households (6%), illness developed in more than one contact. The proportion of household contacts in whom acute respiratory illness developed decreased with the size of the household, from 28% in two-member households to 9% in six-member households. Household contacts 18 years of age or younger were twice as susceptible as those 19 to 50 years of age (relative susceptibility, 1.96; Bayesian 95% credible interval, 1.05 to 3.78; P=0.005), and household contacts older than 50 years of age were less susceptible than those who were 19 to 50 years of age (relative susceptibility, 0.17; 95% credible interval, 0.02 to 0.92; P=0.03). Infectivity did not vary with age. The mean time between the onset of symptoms in a case patient and the onset of symptoms in the household contacts infected by that patient was 2.6 days (95% credible interval, 2.2 to 3.5). The transmissibility of the 2009 H1N1 influenza virus in households is lower than that seen in past pandemics. Most transmissions occur soon before or after the onset of symptoms in a case patient.
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During June 2-8, 2009, an outbreak of influenza A pandemic (H1N1) 2009 occurred among 31 members of a tour group in China. To identify the mode of transmission and risk factors, we conducted a retrospective cohort investigation. The index case-patient was a female tourist from the United States. Secondary cases developed in 9 (30%) tour group members who had talked with the index case-patient and in 1 airline passenger (not a tour group member) who had sat within 2 rows of her. None of the 14 tour group members who had not talked with the index case-patient became ill. This outbreak was apparently caused by droplet transmission during coughing or talking. That airborne transmission was not a factor is supported by lack of secondary cases among fellow bus and air travelers. Our findings highlight the need to prevent transmission by droplets and fomites during a pandemic.
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Norovirus infection outbreaks (NoVOs) occur frequently in closed populations, such as cruise ship passengers. Environmental contamination is believed to play an important role in NoVO propagation. Trained health care professionals covertly evaluated the thoroughness of disinfection cleaning (TDC) of 6 standardized objects (toilet seat, flush handle or button, toilet stall inner handhold, stall inner door handle, restroom inner door handle, and baby changing table surfaces) with high potential for fecal contamination in cruise ship public restrooms, by means of a previously validated novel targeting method. Fifty-six cruise ships (approximately 30% of 180 vessels operated by 9 large cruise lines) were evaluated from July 2005 through August 2008. Overall, 37% (range, 4%-100%; 95% confidence interval, 29.2%-45.4%) of 8344 objects in 273 randomly selected public restrooms were cleaned daily. The TDC did not differ by cruise line and did not correlate with the Centers for Disease Control and Prevention (CDC) Vessel Sanitation Program inspection scores (r(2), .002; P = .75). More than half the vessels had overall TDC scores <30%, although several of these low-scoring ships had near-perfect CDC sanitation scores. The mean TDC of the 3 ships evaluated within 4 months before a NoVO (10.3%) was substantially less than the mean TDC of the 40 ships that did not experience NoVOs (40.4%) (P < .004). An objective evaluation of public restroom environmental hygiene on 56 cruise ships found that only 37% of selected toilet area objects were cleaned on a daily basis. Low TDC scores may predict subsequent NoVO-prone vessels. Enhanced public restroom cleaning may prevent or moderate NoVOs on cruise ships.
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During the containment phase in the United Kingdom (April to June 2009), a cluster of influenza A(H1N1)v cases was identified prompting further investigation and public health action by the Health Protection Agency. The first confirmed case, a pupil at a school in England, was imported. During the following two weeks, 16 further cases were confirmed with epidemiological links to the first imported case. In this cluster, we found that significant transmission occurred in two classes with attack rates of 17.4% and 7.4%. In each of the two classes a case had attended school whilst symptomatic. Other settings included a choir and a party. Minimum and maximum attack rates were 3.6% and 4.2% for the choir and 14.3% and 25% for the party. We did not find any evidence of transmission on two school bus trips despite exposure over 50 minutes to a symptomatic case and over two periods of 30 minutes to a case during the prodromal phase (i.e. within 12 hours of symptom onset). Nor was there onward transmission in another school despite exposure over several hours to two cases, both of whom attended school during the prodromal phase.
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Difficulties in early and accurate diagnosis of intestinal tuberculosis lead to frequent misdiagnosis even in endemic areas. This study aimed to investigate clinical and laboratory characteristics of patients with lower gastrointestinal tract tuberculosis (LGITB). Patients who met the criteria for LGITB in a medical center from 1997 to 2006 were identified and their medical records reviewed. A number of 4,567 patients with culture or histology-proven tuberculosis were identified, and 30 (0.66%) were diagnosed with LGITB. Principal co-morbidities were type II diabetes mellitus (23%) and alcoholism (23%). Twenty-two (73%) had radiographic findings suggestive of pulmonary tuberculosis, which was culture-proven in 13. Mycobacterial cultures from stool or sputum had diagnostic yields of about 50%, comparable to that of histological studies of colonoscopic or surgical biopsies. Multidrug-resistant tuberculosis (MDRTB) was identified in four patients, including two alcoholics. Fourteen underwent surgery; two (14%) received right hemicolectomy under the diagnosis of colon cancer without pre- or intraoperative histological study. The 1-year mortality was 20% but was 50% in patients with MDRTB. A high rate of alcoholism and diabetes mellitus and a high percentage of MDRTB among alcoholics were observed in our patients with LGITB. The diagnostic yields of stool or sputum mycobacterial culture (50%) were similar to that of intestinal histological study. Pre- or intraoperative histological examination could prevent unnecessarily extensive surgery.
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Size-fractionated aerosol particles were collected in a hospital emergency department to test for airborne influenza virus. Using real-time polymerase chain reaction, we confirmed the presence of airborne influenza virus and found that 53% of detectable influenza virus particles were within the respirable aerosol fraction. Our results provide evidence that influenza virus may spread through the airborne route.
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Noroviruses are the most common cause of viral gastroenteritis in the United States. To determine the magnitude and duration of virus shedding in feces, we evaluated persons who had been experimentally infected with Norwalk virus. Of 16 persons, clinical gastroenteritis (watery diarrhea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days. Virus shedding was first detected by reverse transcription-PCR (RT-PCR) 18 hours after participant inoculation and lasted a median of 28 days after inoculation (range 13-56 days). The median peak amount of virus shedding was 95 x 10(9) (range 0.5-1,640 x 10(9)) genomic copies/g feces as measured by quantitative RT-PCR. Virus shedding was first detected by antigen ELISA approximately 33 hours (median 42 hours) after inoculation and lasted 10 days (median 7 days) after inoculation. Understanding of the relevance of prolonged fecal norovirus excretion must await the development of sensitive methods to measure virus infectivity.
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The use of aerosols produced by atomization of suspensions of monodisperse spheres, such as polystyrene latex spheres, is common for testing and calibrating air sampling equipment and studying aerosol behavior. The dilution required to yield a desired fraction of single particles has been customarily determined by trial. In this discussion a formula is developed for estimating the dilution required to produce a given singlet ratio (ratio of single particles to all particles), it being assumed that the atomizer used produces a droplet distribution which is log-normal. It is found that the dilution is proportional to the cube of the droplet distribution median diameter and inversely proportional to the cube of the monodisperse particle diameter. The fraction of droplets which do not contain particles is also calculated; this is found to depend only on the desired singlet ratio and the geometric standard deviation of the droplet distribution.
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Nontuberculous mycobacteria (21 isolates), biochemically similar to those that are recovered from humans, were recovered from rainwater and from natural river waters and their aerosols in the area of Richmond, Virginia. Field experiments have confirmed the existence of a natural mechanism for the transfer of significant numbers of mycobacteria from water to air. These findings support the hypothesis that aerosolization of potentially pathogenic mycobacteria from waters of the southeastern United States may be a major pathway for human infection.
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An outbreak of gastroenteritis followed a meal in a large hotel during which one of the diners vomited. The clinical features of the illness suggested Norwalk-like virus (NLV, small round structured virus) infection, and this was confirmed by electron microscopy and reverse transcriptase polymerase chain reaction (RT-PCR) of stool samples. Further characterization of the virus by nucleotide sequence analysis of the PCR amplicons revealed identical strains in all the affected individuals. The foods served at the meal could not be demonstrated to be the cause of the outbreak. Analysis of attack rates by dining table showed an inverse relationship with the distance from the person who vomited. No one eating in a separate restaurant reported illness. Transmission from person-to-person or direct contamination of food seems unlikely in this outbreak. However, the findings are consistent with airborne spread of NLV with infection by inhalation with subsequent ingestion of virus particles.
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There is uncertainty about the mode of transmission of the severe acute respiratory syndrome (SARS) virus. We analyzed the temporal and spatial distributions of cases in a large community outbreak of SARS in Hong Kong and examined the correlation of these data with the three-dimensional spread of a virus-laden aerosol plume that was modeled using studies of airflow dynamics. We determined the distribution of the initial 187 cases of SARS in the Amoy Gardens housing complex in 2003 according to the date of onset and location of residence. We then studied the association between the location (building, floor, and direction the apartment unit faced) and the probability of infection using logistic regression. The spread of the airborne, virus-laden aerosols generated by the index patient was modeled with the use of airflow-dynamics studies, including studies performed with the use of computational fluid-dynamics and multizone modeling. The curves of the epidemic suggested a common source of the outbreak. All but 5 patients lived in seven buildings (A to G), and the index patient and more than half the other patients with SARS (99 patients) lived in building E. Residents of the floors at the middle and upper levels in building E were at a significantly higher risk than residents on lower floors; this finding is consistent with a rising plume of contaminated warm air in the air shaft generated from a middle-level apartment unit. The risks for the different units matched the virus concentrations predicted with the use of multizone modeling. The distribution of risk in buildings B, C, and D corresponded well with the three-dimensional spread of virus-laden aerosols predicted with the use of computational fluid-dynamics modeling. Airborne spread of the virus appears to explain this large community outbreak of SARS, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus.
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Microbial contamination of bathrooms by aerosols generated by toilet flushing has been previously demonstrated. In this study, the impact of automatic bowl cleaners on aerosol generation was evaluated. Three toilet bowl cleaners which contained 2.5, 6.7 or 18.2% surfactant materials were evaluated. Results indicated that these cleaners significantly (p≤0.05) reduced the numbers of bacteria ejected from the bowl, and that the cleaner containing the greatest amount of surfactant was the most effective in aerosol reduction.
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The survival and environmental spread of Salmonella bacteria from domestic toilets was examined in homes, where a family member had recently suffered an attack of salmonellosis. In four out of six households tested, Salmonella bacteria persisted in the biofilm material found under the recess of the toilet bowl rim which was difficult to remove with household toilet cleaners. In two homes Salmonella bacteria became incorporated into the scaly biofilm adhering to the toilet bowl surface below the water line. Salmonella enteritidis persisted in one toilet for 4 weeks after the diarrhoea had stopped, despite the use of cleaning fluids. Salmonellas were not isolated from normally dry areas such as, the toilet seat, the flush handle and door handle. Toilet seeding experiments were set up with Salmonella enteritidis PT4 to mimic environmental conditions associated with acute diarrhoea. Flushing the toilet resulted in contamination of the toilet seat and the toilet seat lid. In one out of three seedings, Salmonella bacteria were also isolated from an air sample taken immediately after flushing, indicating that airborne spread of the organism could contaminate surfaces in the bathroom. In the seeded toilet Salmonella bacteria were isolated from the biofilm in the toilet bowl below the waterline for up to 50 d after seeding, and also on one occasion from the bowl water. The results suggest that during diarrhoeal illness, there is considerable risk of spread of Salmonella infection to other family members via the environment, including contaminated hands and surfaces in the toilet area.
Article
Toilet facilities in healthcare settings vary widely, but patient toilets are commonly shared and do not have lids. When a toilet is flushed without the lid closed, aerosol production may lead to surface contamination within the toilet environment. To substantiate the risks of airborne dissemination of C. difficile following flushing a toilet, in particular when lids are not fitted. We performed in-situ testing, using faecal suspensions of C. difficile to simulate the bacterial burden found during disease, to measure C. difficile aerosolization. We also measured the extent of splashing occurring during flushing of two different toilet types commonly used in hospitals. C. difficile was recoverable from air sampled at heights up to 25 cm above the toilet seat. The highest numbers of C. difficile were recovered from air sampled immediately following flushing, and then declined 8-fold after 60 min and a further 3-fold after 90 min. Surface contamination with C. difficile occurred within 90 min after flushing, demonstrating that relatively large droplets are released which then contaminate the immediate environment. The mean numbers of droplets emitted upon flushing by the lidless toilets in clinical areas were 15-47, depending on design. C. difficile aerosolization and surrounding environmental contamination occur when a lidless toilet is flushed. Lidless conventional toilets increase the risk of C. difficile environmental contamination, and we suggest that their use is discouraged, particularly in settings where CDI is common.
Article
Viral shedding profile of infections caused by the pandemic H1N1 2009 influenza A virus has not been reported. The aim of this study was to determine the viral load in different body sites. Viral loads of pandemic H1N1 virus in respiratory specimens, stool, urine, and serum were determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Respiratory specimens from patients with seasonal influenza were used as historical controls. Initial pre-treatment viral load were compared between these two groups. Serial respiratory specimens from patients with pandemic H1N1 virus infection were obtained for analysis of viral dynamics. Twenty-two pandemic H1N1 cases and 44 seasonal influenza historical controls were included. The mean initial viral load before oseltamivir therapy was 1.84 x 10(8) copies/ml for pandemic H1N1 virus compared with 3.28 x 10(8) copies/ml in seasonal influenza historical controls (P = 0.085). Among patients with pandemic H1N1 virus infection, peak viral load occurred on the day of onset of symptoms, and declined gradually afterwards, with no virus being detectable in respiratory specimens by RT-PCR 8 days and by culture 5 days after the onset of symptoms respectively, except in one patient. Pandemic H1N1 virus was detected in stool and in urine from 4/9 and 1/14 patients, respectively. Viral culture was also positive from the stool sample with the highest viral load. Younger age was associated with prolonged shedding in the respiratory tract and higher viral load in the stool. Data from this quantitative analysis of viral shedding may have implications for formulating infection control measures.
Article
Noroviruses are now recognized as the leading cause of epidemics of gastroenteritis and an important cause of sporadic gastroenteritis among both children and adults. In the United States, more than 90% of the outbreaks of gastroenteritis for which the cause could not previously be identified can now be attributed to this virus. Understanding the nature of immunity to the norovirus is a key determinant for future improvements in the control and prevention of this viral infection.
Article
We studied the bacterial burden on toilet seats in a children's cancer hospital to validate a policy requesting that immunocompromised children use alcohol wipes on the seats prior to use of the toilets. Methicillin-resistant Staphylococcus aureus (MRSA) was recovered from 3.3% of hospital toilets when wipes were not in use. Use of wipes resulted in a 50-fold reduction in mean daily bacterial counts and eliminated MRSA. © 2009 Association for Professionals in Infection Control and Epidemiology, Inc.
Article
Large numbers of bacteria and viruses when seeded into household toilets were shown to remain in the bowl after flushing, and even continual flushing could not remove a persistent fraction. This was found to be due to the adsorption of the organsims to the porcelain surfaces of the bowl, with gradual elution occuring after each flush. Droplets produced by flushing toilets were found to harbor both bacteria and viruses which had been seeded. The detection of bacteria and firuses falling out onto surfaces in bathrooms after flushing indicated that they remain airborne long enough to settle on surfaces throughout the bathroom. Thus, there is a possibility that a person may acquire an infection from an aerosol produced by a toilet.