Identifying septic pollution exposure routes during a waterborne norovirus outbreak - A new application for human-associated microbial source tracking qPCR.

In June 2017, the Pennsylvania Department of Health (PADOH) was notified of multiple norovirus outbreaks associated with 179 ill individuals who attended separate events held at an outdoor venue and campground over a month period. Epidemiologic investigations were unable to identify a single exposure route and therefore unable to determine whether there was a persistent contamination source to target for exposure mitigation. Norovirus was detected in a fresh recreational water designated swimming area and a drinking water well. A hydrogeological site evaluation suggested a nearby septic leach field as a potential contamination source via ground water infiltration. Geological characterization revealed a steep dip of the bedrock beneath the septic leach field toward the well, providing a viral transport pathway in a geologic medium not previously documented as high risk for viral ground water contamination. The human-associated microbial source tracking (MST) genetic marker, HF183, was used as a microbial tracer to demonstrate the hydrogeological connection between the malfunctioning septic system, drinking water well, and recreational water area. Based on environmental investigation findings, venue management and local public health officials implemented a series of outbreak prevention strategies including discontinuing the use of the contaminated well, issuing a permit for a new drinking water well, increasing portable toilet and handwashing station availability, and promoting proper hand hygiene. Despite the outbreaks at the venue and evidence of ground water contamination impacting nearby recreational water and the drinking water well, no new norovirus cases were reported during a large event one week after implementing prevention practices. This investigation highlights a new application for human-associated MST methods to trace hydrological connections between multiple fecal pollutant exposure routes in an outbreak scenario. In turn, pollutant source information can be used to develop effective intervention practices to mitigate exposure and prevent future outbreaks associated with human fecal contaminated waters.

Variation in microparasite free-living survival and indirect transmission can modulate the intensity of emerging outbreaks.

Variation in free-living microparasite survival can have a meaningful impact on the ecological dynamics of established and emerging infectious diseases. Nevertheless, resolving the importance of indirect and environmental transmission in the ecology of epidemics remains a persistent challenge. It requires accurately measuring the free-living survival of pathogens across reservoirs of various kinds and quantifying the extent to which interaction between hosts and reservoirs generates new infections. These questions are especially salient for emerging pathogens, where sparse and noisy data can obfuscate the relative contribution of different infection routes. In this study, we develop a mechanistic, mathematical model that permits both direct (host-to-host) and indirect (environmental) transmission and then fit this model to empirical data from 17 countries affected by an emerging virus (SARS-CoV-2). From an ecological perspective, our model highlights the potential for environmental transmission to drive complex, nonlinear dynamics during infectious disease outbreaks. Summarizing, we propose that fitting alternative models with indirect transmission to real outbreak data from SARS-CoV-2 can be useful, as it highlights that indirect mechanisms may play an underappreciated role in the dynamics of infectious diseases, with implications for public health.

Occurrence of four waterborne viruses at five typical raw water resources in the Republic of Korea during August 2013 to February 2019.

Waterborne diseases have critical public health issues and socioeconomic relevancy worldwide. Various viral pathogens are ordinarily associated with waterborne diseases. Six-year-surveillance (a total of 20 times) of norovirus, hepatitis A virus, group C rotavirus, and enterovirus was conducted at five raw water sampling sites including two lakes (Lakes Soyang and Juam), Hyundo region of Geum River in Daejeon City, and Guui region of Han River in Seoul Metropolitan City and Moolgeum region of Nakdong River in Gimhae City which are located near two water intake plants. In this study, we routinely investigated virus contamination in water samples through reverse transcription polymerase chain reaction (RT-PCR) and integrated cell culture RT-PCR with high sensitivity and specificity. A total 100 samples were tested. Most of the targeted viruses were found in 32% of the samples and at least one of the indicator bacteria was detected in 65% of these occurrences. Among all the detected viruses, enterovirus was the most prevalent with a detection frequency of 12% and 2.71 MPN/10 L on average, while hepatitis A virus was the least prevalent with a detection frequency of 4%. Nearly all of the analyzed viruses (except for group C rotavirus) were present in samples from Han River (the Guui region), Geum River (the Hyundo region), Lake Juam, and Nakdong River (the Moolgeum region), while group C rotavirus was detected in those from the Guui region. During the six-year sampling period, the targeted waterborne viruses in water samples exhibited seasonal patterns in their occurrence that were different from the indicator bacteria levels in the water samples. The fact that they were detected in the five representative Korean water environments makes it necessary to establish the chemical and biological analysis systems for waterborne viruses and sophisticated management systems.

[Waterborne outbreaks in Iceland - analysis of scale and causes]. / Vatnsbornar hópsýkingar á Íslandi - greining á umfangi og ástæðum

PURPOSE: Clean drinking water is essential for public health. The cause of waterborne outbreaks is most often faecal contamination of water from animals or humans. The objective of this resarch was to collect available information on waterborne outbreaks in Iceland for the twenty year period, 1998-2017. Incident of faecal and pathogenic pollution in samples where also collected even though rarely followed by registered outbreak. METHODS: Data are obtained from laboratory databases, the Directorate of Health, reports and interviews with the relevant surveillance authorities and epidemiologists. RESULTS: The results show that for the period investigated fifteen waterborne outbreaks were registered, all in small water supplies, many of which served transitent population, tourists and summerhouse dwellers. About 500 illnesses were confirmed and 8000 people affected. Other research have shown that around 10% of illnesses in waterborne outbreaks are registered so it can be estimated that on average 250 people have been taken ill every year because of contaminated drinking water. Analysis of monitoring water quality data show that on average 50 water supplies, or about 5% of the Icelandic registered water supplies have contained faecal matter every year. The most frequent cause of waterborne outbreak were poor design and inadequate maintainance of water intakes. CONCLUSIONS: It is likely that waterborne outbreaks are more numerous than are registered in official reports, especially concerning small water supplies. It also seems that the local heath authorities are often not informed of incidents of non-compliance. It is important to improve registration, information exchange between parties, epidemiological surveys and follow up of outbreaks due to drinking water to gather lessons learned. Water quality at small water supplies needs to be improved with risk-based approach and risk management.

Hepatitis E virus outbreak associated with rainfall in the Central African Republic in 2008-2009.

BACKGROUND: Infection by hepatitis E virus (HEV) can cause a high burden of morbidity and mortality in countries with poor access to clean water and sanitation. Our study aimed to investigate the situation of HEV infections in the Central African Republic (CAR). METHODS: A retrospective analysis of the blood samples and notification forms collected through the national yellow fever (YF) surveillance program, but for which a diagnosis of YF was discarded, was carried out using an anti-HEV IgM ELISA and a HEV-specific RT-PCR. RESULTS: Of 2883 YF-negative samples collected between January 2008 and December 2012, 745 (~ 26%) tested positive by at least either of the 2 tests used to confirm HEV cases. The results revealed that the CAR was hit by a large HEV outbreak in 2008 and 2009. The results also showed a clear seasonal pattern with correlation between HEV incidence and rainfall in Bangui. A phylogenetic analysis showed that the circulating strains belonged to genotypes 1e and 2b. CONCLUSIONS: Overall, this study provides further evidences that HEV can be a significant cause of acute febrile jaundice, particularly among adults during rainy season or flood, in a country from Sub-Saharan Africa.

Infectivity of Norovirus GI and GII from Bottled Mineral Water during a Waterborne Outbreak, Spain.

During a waterborne outbreak of norovirus in Spain, we estimated 50% illness doses for a group of exposed (secretor) persons to be 556 (95% CI 319-957) genome copies/day for norovirus GI and 2,934 (95% CI 1,683-5,044) genome copies/day for norovirus GII. Use of a propidium monoazide viability assay reduced these values.

Control of Waterborne Human Viruses by Indigenous Bacteria and Protists Is Influenced by Temperature, Virus Type, and Microbial Species.

Human viruses are ubiquitous contaminants in surface waters, where they can persist over extended periods of time. Among the factors governing their environmental persistence, the control (removal or inactivation) by microorganisms remains poorly understood. Here, we determined the contribution of indigenous bacteria and protists to the decay of human viruses in surface waters. Incubation of echovirus 11 (E11) in freshwater from Lake Geneva and seawater from the Mediterranean Sea led to a 2.5-log10 reduction in the infectious virus concentration within 48 h at 22°C, whereas E11 was stable in sterile controls. The observed virus reduction was attributed to the action of both bacteria and protists in the biologically active matrices. The effect of microorganisms on viruses was temperature dependent, with a complete inhibition of microbial virus control in lake water at temperatures of ≤16°C. Among three protist isolates tested (Paraphysomonas sp., Uronema marinum, and Caecitellus paraparvulus), Caecitellus paraparvulus was particularly efficient at controlling E11 (2.1-log10 reduction over 4 days with an initial protist concentration of 103 cells ml-1). In addition, other viruses (human adenovirus type 2 and bacteriophage H6) exhibited different grazing kinetics than E11, indicating that the efficacy of antiviral action also depended on the type of virus. In conclusion, indigenous bacteria and protists in lake water and seawater can modulate the persistence of E11. These results pave the way for further research to understand how microorganisms control human viral pathogens in aquatic ecosystems and to exploit this process as a treatment solution to enhance microbial water safety.IMPORTANCE Waterborne human viruses can persist in the environment, causing a risk to human health over long periods of time. In this work, we demonstrate that in both freshwater and seawater environments, indigenous bacteria and protists can graze on waterborne viruses and thereby reduce their persistence. We furthermore demonstrate that the efficiency of the grazing process depends on temperature, virus type, and protist species. These findings may facilitate the design of biological methods for the disinfection of water and wastewater.

Point-of-Care Strategies for Detection of Waterborne Pathogens.

Waterborne diseases that originated due to pathogen microorganisms are emerging as a serious global health concern. Therefore, rapid, accurate, and specific detection of these microorganisms (i.e., bacteria, viruses, protozoa, and parasitic pathogens) in water resources has become a requirement of water quality assessment. Significant research has been conducted to develop rapid, efficient, scalable, and affordable sensing techniques to detect biological contaminants. State-of-the-art technology-assisted smart sensors have improved features (high sensitivity and very low detection limit) and can perform in a real-time manner. However, there is still a need to promote this area of research, keeping global aspects and demand in mind. Keeping this view, this article was designed carefully and critically to explore sensing technologies developed for the detection of biological contaminants. Advancements using paper-based assays, microfluidic platforms, and lateral flow devices are discussed in this report. The emerging recent trends, mainly point-of-care (POC) technologies, of water safety analysis are also discussed here, along with challenges and future prospective applications of these smart sensing technologies for water health diagnostics.

A Review and Update on Waterborne Viral Diseases Associated with Swimming Pools.

Infectious agents, including bacteria, viruses, protozoa, and molds, may threaten the health of swimming pool bathers. Viruses are a major cause of recreationally-associated waterborne diseases linked to pools, lakes, ponds, thermal pools/spas, rivers, and hot springs. They can make their way into waters through the accidental release of fecal matter, body fluids (saliva, mucus), or skin flakes by symptomatic or asymptomatic carriers. We present an updated overview of epidemiological data on viral outbreaks, a project motivated, among other things, by the availability of improved viral detection methodologies. Special attention is paid to outbreak investigations (source of the outbreak, pathways of transmission, chlorination/disinfection). Epidemiological studies on incidents of viral contamination of swimming pools under non-epidemic conditions are also reviewed.

Application of a salivary immunoassay in a prospective community study of waterborne infections.

Quantifying sporadic waterborne infections in community settings can be challenging. Salivary antibody immunoassays are a promising non-invasive tool that can be used in prospective studies of common infections, especially those involving children. This study was conducted in a Massachusetts city, which uses a microbiologically contaminated river as its water source, during summer-early winter periods before and after construction of a new drinking water treatment plant. Monthly saliva samples (7480 samples from 1170 children and 816 adults) were analyzed for immunoglobulin G (IgG) responses to recombinant proteins of Cryptosporidium, one genogroup I (GI) and two GII noroviruses. Immunoconversion was defined as at least four-fold increase in specific antibody responses between two monthly samples with a post-conversion response above a flexible age-dependent cut-off. Episodes of gastroenteritis (diarrhea or vomiting or cramps) were associated with 3.2 (95% confidence limits 1.1; 9.5) adjusted odds ratio (aOR) of immunoconversion to Cryptosporidium; episodes of combined diarrhea and vomiting symptoms were associated with 3.5 (0.8; 15.0) and 4.6 (1.7; 12.6) aORs of an immunoconversion to GI and GII noroviruses, respectively. Swimming in natural water bodies or chlorinated pools was associated with 2.3 (0.4; 15.4) and 4.9 (1.6; 15.5) aORs of immunoconversion to Cryptosporidium, respectively. In a subset of study participants who did not use home water filters, consumption of at least some amount of non-boiled tap water reported in a monthly recall survey was associated with 11.1 (1.2; 100.0) and 0.6 (0.1; 2.5) aORs of immunoconversion to Cryptosporidium before and after the new water treatment plant construction, respectively. Among individuals who used home water filters, associations between non-boiled tap water consumption and Cryptosporidium immunoconversion were not significant before and after new plant construction with aORs of 0.8 (0.2; 3.3) and 0.3 (0.1; 1.6), respectively. The interaction effect of study phase and non-boiled tap water consumption on Cryptosporidium immunoconversions was statistically significant in the entire study population with aOR of 5.4 (1.1; 25.6). This was the first study that has used a salivary antibody immunoassay to demonstrate significant associations between gastrointestinal symptoms and Cryptosporidium and norovirus infections, and between water-related exposures and Cryptosporidium infections.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries.

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Waterborne Norovirus outbreak at a seaside resort likely originating from municipal water distribution system failure.

In May 2016 a Norovirus (NoV) gastroenteritis outbreak involved a high school class visiting a seaside resort near Taormina (Mascali, Sicily). Twenty-four students and a teacher were affected and 17 of them showed symptoms on the second day of the journey, while the others got ill within the following 2 days. Symptoms included vomiting, diarrhoea and fever, and 12 students required hospitalisation. Stool samples tested positive for NoV genome by Real-Time polymerase chain reaction assay in all 25 symptomatic subjects. The GII.P2/GII.2 NoV genotype was linked to the outbreak by ORF1/ORF2 sequence analysis. The epidemiological features of the outbreak were consistent with food/waterborne followed by person-to-person and/or vomit transmission. Food consumed at a shared lunch on the first day of the trip was associated to illness and drinking un-bottled tap water was also considered as a risk factor. The analysis of water samples revealed the presence of bacterial indicators of faecal contamination in the water used in the resort as well as in other areas of the municipal water network, linking the NoV gastroenteritis outbreak to tap water pollution from sewage leakage. From a single water sample, an amplicon whose sequence corresponded to the capsid genotype recovered from patients could be obtained.

Virus-Bacteria Interactions: Implications and Potential for the Applied and Agricultural Sciences.

Eukaryotic virus-bacteria interactions have recently become an emerging topic of study due to multiple significant examples related to human pathogens of clinical interest. However, such omnipresent and likely important interactions for viruses and bacteria relevant to the applied and agricultural sciences have not been reviewed or compiled. The fundamental basis of this review is that these interactions have importance and deserve more investigation, as numerous potential consequences and applications arising from their discovery are relevant to the applied sciences. The purpose of this review is to highlight and summarize eukaryotic virus-bacteria findings in the food/water, horticultural, and animal sciences. In many cases in the agricultural sciences, mechanistic understandings of the effects of virus-bacteria interactions remain unstudied, and many studies solely focus on co-infections of bacterial and viral pathogens. Given recent findings relative to human viral pathogens, further research related to virus-bacteria interactions would likely result in numerous discoveries and beneficial applications.

Enteric viruses' dissemination in a private reserve of natural heritage.

This study aimed to assess anthropogenic impact of surrounding population in the Private Reserve of Natural Heritage at Pantanal, the world's largest freshwater wetland ecosystem located in the centre of South America. Viral aetiological agents of acute gastroenteritis as rotavirus A (RVA), noroviruses, human adenoviruses, klassevirus and of hepatitis, as hepatitis A virus, were investigated in different aquatic matrices. Annual collection campaigns were carried out from 2009 to 2012, alternating dry and rainy seasons. Viral particles present in the samples were concentrated by the adsorption-elution method, with negatively charged membranes, and detected by qualitative and quantitative PCR. From a total of 43 samples at least one virus was detected in 65% (28) of them. Viruses were detected in all matrices with concentrations ranging from 2 × 102 to 8·3 × 104 genome copies per litre. A significant higher RVA frequency was observed in the dry season. Our data revealing dissemination of human enteric viruses in water matrices both inside and outside the reserve could be useful to trace faecal contamination in the environment and to minimize the risk of infection by exposure of susceptible individuals. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is part of a collaborative project designed to investigate the environmental and health conditions of the Private Reserve of Natural Heritage at Pantanal, the largest seasonally flooded wetland in the world. The project aimed to promote health and quality of human and wildlife extending technical-scientific knowledge about pathogens present in the region. By assessing the occurrence of human enteric viruses in different water matrices we demonstrated the anthropogenic impact of surrounding population and pointed out the potential risk of infection by exposure of susceptible individuals.

The impact of anthropogenic pressure on the virological quality of water from the Tiber River, Italy.

The objective of the present study was to assess the occurrence of major waterborne enteric viruses (enterovirus, norovirus, adenovirus, rotavirus, hepatitis A and E virus) along the Tiber River in Italy, in areas affected by different kinds of anthropogenic pressure (agricultural, urban, industrial and pristine). Moreover, in light of the recent abundant detection of human bocavirus in urban wastewater samples in Italy, the occurrence of this virus was also assessed. Virus detection was based on nested PCR followed by sequencing, and on real-time PCR. A correlation with anthropogenic pressure was observed. The urban and industrial areas were the most contaminated (100 and 75% of samples were positive for at least one virus respectively). The agricultural area was less contaminated, with 50% of samples positive. None of the samples collected in a pristine area were positive for viruses. The most frequently detected virus was human bocavirus, identified in 37·5% of samples, followed by norovirus and enterovirus (28% each) and adenovirus (21·6%). Rotavirus, and hepatitis A and E viruses were less common (<9%). Although Human Bocavirus is not considered a waterborne pathogen, the widespread contamination of river waters suggests that virus transmission via the water route should not be neglected. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, this study constitutes the first attempt to assess the occurrence of enteric viruses in river waters, in areas differentially influenced by anthropogenic pressure. Enteric viruses (enterovirus, norovirus, adenovirus, rotavirus, hepatitis A and E viruses, and bocavirus) were widespread in the industrial and urban areas, and were less frequently detected in the agricultural area. Interestingly, human bocavirus was the most frequently detected virus, outnumbering even adenoviruses, known to be widespread in water environments. The widespread presence of bocavirus in surface waters suggests that a potential role of water in its transmission should not be excluded.

Burden of Disease Attributed to Waterborne Transmission of Selected Enteric Pathogens, Australia, 2010.

AbstractUniversal access to safe drinking water is a global priority. To estimate the annual disease burden of campylobacteriosis, nontyphoidal salmonellosis, cryptosporidiosis, giardiasis, and norovirus attributable to waterborne transmission in Australia, we multiplied regional World Health Organization (WHO) estimates of the proportion of cases attributable to waterborne transmission by estimates of all-source disease burden for each study pathogen. Norovirus was attributed as causing the most waterborne disease cases (479,632; 95% uncertainty interval [UI]: 0-1,111,874) followed by giardiasis and campylobacteriosis. The estimated waterborne disability-adjusted life year (DALY) burden for campylobacteriosis (2,004; 95% UI: 0-5,831) was 7-fold greater than other study pathogens and exceeded the WHO guidelines for drinking water quality (1 × 10-6 DALY per person per year) by 90-fold. However, these estimates include disease transmitted via either drinking or recreational water exposure. More precise country-specific and drinking water-specific attribution estimates would better define the health burden from drinking water and inform changes to treatment requirements.

Mortality from selected diseases that can be transmitted by water - United States, 2003-2009.

Diseases spread by water are caused by fecal-oral, contact, inhalation, or other routes, resulting in illnesses affecting multiple body systems. We selected 13 pathogens or syndromes implicated in waterborne disease outbreaks or other well-documented waterborne transmission (acute otitis externa, Campylobacter, Cryptosporidium, Escherichia coli (E. coli), free-living ameba, Giardia, Hepatitis A virus, Legionella (Legionnaires' disease), nontuberculous mycobacteria (NTM), Pseudomonas-related pneumonia or septicemia, Salmonella, Shigella, and Vibrio). We documented annual numbers of deaths in the United States associated with these infections using a combination of death certificate data, nationally representative hospital discharge data, and disease-specific surveillance systems (2003-2009). We documented 6,939 annual total deaths associated with the 13 infections; of these, 493 (7%) were caused by seven pathogens transmitted by the fecal-oral route. A total of 6,301 deaths (91%) were associated with infections from Pseudomonas, NTM, and Legionella, environmental pathogens that grow in water system biofilms. Biofilm-associated pathogens can cause illness following inhalation of aerosols or contact with contaminated water. These findings suggest that most mortality from these 13 selected infections in the United States does not result from classical fecal-oral transmission but rather from other transmission routes.

Safe drinking water and waterborne outbreaks.

The present work compiles a review on drinking waterborne outbreaks, with the perspective of production and distribution of microbiologically safe water, during 2000-2014. The outbreaks are categorised in raw water contamination, treatment deficiencies and distribution network failure. The main causes for contamination were: for groundwater, intrusion of animal faeces or wastewater due to heavy rain; in surface water, discharge of wastewater into the water source and increased turbidity and colour; at treatment plants, malfunctioning of the disinfection equipment; and for distribution systems, cross-connections, pipe breaks and wastewater intrusion into the network. Pathogens causing the largest number of affected consumers were Cryptosporidium, norovirus, Giardia, Campylobacter, and rotavirus. The largest number of different pathogens was found for the treatment works and the distribution network. The largest number of affected consumers with gastrointestinal illness was for contamination events from a surface water source, while the largest number of individual events occurred for the distribution network.

Environmental contamination and risk factors for transmission of highly pathogenic avian influenza A(H5N1) to humans, Cambodia, 2006-2010.

BACKGROUND: Highly pathogenic avian influenza A (H5N1) virus has been of public health concern since 2003. Probable risk factors for A(H5N1) transmission to human have been demonstrated in several studies or epidemiological reports. However, transmission patterns may differ according to demographic characteristics of the population and local practices. This article aggregates these data from three studies with data collected in the previous surveys in 2006 and 2007 to further examine the risks factors associated with presence of anti-A(H5) antibodies among villagers residing within outbreak areas. METHODS: We aggregated 5-year data (2006-2010) from serology survey and matched case-control studies in Cambodia to further examine the risks factors associated with A(H5N1) infection among villagers in the outbreak areas. RESULTS: Serotesting among villagers detected 35 (1.5 % [0-2.6]) positive cases suggesting recent exposure to A(H5N1) virus. Practices associated with A(H5N1) infection among all ages were: having poultry cage or nesting area under or adjacent to the house (OR: 6.7 [1.6-28.3]; p = 0.010) and transporting poultry to market (OR: 17.6 [1.6-193.7]; p = 0.019). Practices found as risk factors for the infection among age under 20 years were swimming/bathing in ponds also accessed by domestic poultry (OR: 4.6 [1.1-19.1]; p = 0.038). Association with consuming wild birds reached borderline significance (p = 0.066). CONCLUSION: Our results suggest that swimming/bathing in contaminated pond water and close contact with poultry may present a risk of A(H5N1) transmission to human.