Waterborne Outbreak Of Gastroenteritis Research Articles

An extensive gastroenteritis outbreak after drinking-water contamination by sewage effluent, Finland

An inappropriate cross-connection between sewage- and drinking-water pipelines contaminated tap water in a Finnish town, resulting in an extensive waterborne gastroenteritis outbreak in this developed country. According to a database and a line-list, altogether 1222 subjects sought medical care as a result of this exposure. Seven pathogens were found in patient samples of those who sought treatment. To establish the true disease burden from this exposure, we undertook a population-based questionnaire investigation with a control population, infrequently used to study waterborne outbreaks. The study covered three areas, contaminated and uncontaminated parts of the town and a control town. An estimated 8453 residents fell ill during the outbreak, the excess number of illnesses being 6501. Attack rates were 53% [95% confidence interval (CI) 49.5-56.4] in the contaminated area, 15.6% (95% CI 13.1-18.5) in the uncontaminated area and 6.5% (95% CI 4.8-8.8) in the control population. Using a control population allowed us to differentiate baseline morbidity from the observed morbidity caused by the water contamination, thus enabling a more accurate estimate of the disease burden of this outbreak.

Bacteria, genetics and irritable bowel syndrome

Evaluation of: Villani AC, Lemire M, Thabane M et al. Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis. Gastroenterology 138, 1502–1513 (2010).While the pathogenesis of irritable bowel syndrome (IBS) remains to be fully defined, two clinical observations – the occurrence, de novo, of IBS following bacterial gastroenteritis and the history, commonly obtained from IBS patients, of other instances of the syndrome within their families – have instigated investigations, in IBS, of the potential roles, on the one hand, of the gut microbiota and the host response and, on the other hand, of genetic factors. The study reviewed here relates to both of these factors by studying genetic predisposition to postinfective IBS in a large population of individuals who were exposed to a multimicrobial enteric infection, which resulted in a severe outbreak of gastroenteritis and was followed by the development of IBS in over a third. In this detailed study, the investigators identified a number of genes that were linked significantly to the development of postinfectious-IBS in the Toll-like receptor 9, IL-6 and cadherin 1 regions. These genes play important roles in bacterial recognition, the inflammatory response and epithelial integrity, respectively, and provide considerable support for the hypothesis that links IBS onset to disturbances in the microbiota and the host response.

Waterborne gastroenteritis outbreak at a scouting camp caused by two norovirus genogroups: GI and GII

Background A cross-border gastroenteritis outbreak at a scouting camp was associated with drinking water from a farmer's well. Objectives A retrospective cohort study was performed to identify size and source of the outbreak, as well as other characteristics. Study design Epidemiological investigation included standardized questionnaires about sex, age, risk exposures, illness and family members. Stool and water (100 mL) samples were analyzed for bacteria, viruses and parasites. Results Questionnaires were returned by 84 scouts (response rate 82%), mean age of 13 years. The primary attack rate was 85% (diarrhoea and/or vomiting). Drinking water was the strongest independent risk factor showing a dose–response effect with 50%, 75%, 75%, 93% and 96% case prevalence for 0, 1, 2–3, 4–5 and >5 glasses consumed, respectively. Norovirus (GI.2 Southampton and GII.7 Leeds) was detected in 51 stool specimens (75%) from ill scouts. Water analysis showed fecal contamination, but no norovirus. The secondary attack rate was 20%. Conclusions This remarkable outbreak was caused by a point-source infection with two genogroups of noroviruses most likely transmitted by drinking water from a well. Finding a dose–response relationship was striking. Specific measures to reduce the risk of waterborne diseases, outbreak investigation and a good international public health network are important.

Genetic Risk Factors for Post-Infectious Irritable Bowel Syndrome Following a Waterborne Outbreak of Gastroenteritis

Acute gastroenteritis is the strongest risk factor for irritable bowel syndrome (IBS). In May 2000, >2300 residents of Walkerton, Ontario, developed gastroenteritis from microbial contamination of the municipal water supply; a longitudinal study found that >36.2% of these developed IBS. We used this cohort to study genetic susceptibility to post-infectious (PI)-IBS. We screened 79 functional variants of genes with products involved in serotoninergic pathways, intestinal epithelial barrier function, and innate immunity and performed fine mapping in regions of interest. We compared data from Walkerton residents who developed gastroenteritis and reported PI-IBS 2 to 3 years after the outbreak (n = 228, cases) with data from residents who developed gastroenteritis but did not develop PI-IBS (n = 581, controls). Four variants were associated with PI-IBS, although the association was not significant after correction for the total number of single nucleotide polymorphisms. Two were located in TLR9, which encodes a pattern recognition receptor (rs352139, P545P; P = .0059 and rs5743836, -T1237C; P = .0250; r(2) < 0.14); 1 was in CDH1, which encodes a tight junction protein (rs16260, -C160A; P = .0352); and 1 was in IL6, which encodes a cytokine (rs1800795, -G174C; P = .0420). Denser mapping of these 3 regions revealed 1 novel association in IL6 (rs2069861; P = .0069) and 14 associations that could be accounted for by linkage disequilibrium with the 4 original variants. The TLR9, IL6, and CDH1 variants all persisted as independent risk factors for PI-IBS when controlling for previously identified clinical risk factors. This is the first descriptive study to assess potential genetic determinants of PI-IBS. Genes that encode proteins involved in epithelial cell barrier function and the innate immune response to enteric bacteria are associated with development of IBS following acute gastroenteritis.

Post-earthquake outbreak of rotavirus gastroenteritis in Kashmir (India): An epidemiological analysis

An earthquake struck Kashmir on 8 October 2005. A central team of public health specialists was sent to Kashmir to assess the public health measures required following the earthquake, and to assist in institution of public health measures. Epidemiological and environmental investigation in Tangdar block (Kupwara district) and Uri Tehsil (Baramula district). Visits to villages affected by the earthquake, rehabilitation camps and health care, examination of cases with acute diarrhoeal disease (ADD), environmental observations, collection of clinical samples from ADD cases and environmental samples from drinking water sources, and laboratory methods. In total, 1783 cases of ADD were reported between 14 October and 17 December 2005 in Tangdar (population 65000). The overall attack rate was 20% in children under 4 years of age. Twelve cases of ADD with loose motions without blood were studied, and 11 rectal swabs and one stool sample were processed. No bacterial enteropathogens could be isolated, but three of the 12 samples yielded rotavirus antigen on enzyme-linked immunosorbent assay. Twelve of 13 (92.3%) water samples, collected from various stream or tap water (source: spring/stream) sources, were unsatisfactory (P=0.001) using the H(2)S strip method compared with other sources (well/mineral water). All eight water sources in Tangdar block were unsatisfactory, indicated by blackening of H(2)S filter paper strips. Following the earthquake, drinking stream water or tap water without boiling or chlorination may have led to a common source water-borne outbreak of rotavirus gastroenteritis. Other contributing factors were: overcrowding; poor sanitation; open-air defaecation; poor hygiene; and living in makeshift camps near streams. Person-to-person transmission may also have contributed to perpetuation of the outbreak. Following the establishment of medical camps and information, education and communication regarding the need to drink boiled water and follow safer hygienic practices, the outbreak was brought under control. The earthquake in Kashmir in 2005 led to widespread contamination of drinking water sources such as stream and tap water (source: stream or spring). This appears to have led to a common source outbreak of rotavirus between October and December 2005, leading to ADD, amongst infants and small children, transmitted by the faecal-oral route and perpetuated by person-to-person transmission.

Lessons learned from ten investigations of waterborne gastroenteritis outbreaks, France, 1998–2006

Ten outbreaks of waterborne acute gastroenteritis (AGE) have been investigated in France since 1998. These outbreaks have affected populations of over 1,000 people, with generally high attack rates. The causal agents have been identified in six of these events. Aetiologies involved mainly noroviruses and Cryptosporidium sp. The point of entry of the contamination was located in the distribution network in five outbreaks (waste water backflows in four cases and one case of contamination induced by maintenance work) and at the water collection facilities in five other cases. Once the outbreak was detected, epidemiological and environmental investigations and crisis management followed well-established procedures. Further progress in public health surveillance will depend on more complete and rapid detection and reporting. Automated analysis of health insurance data on the reimbursement of drugs for AGE should help make detection more complete. Improved reactivity depends primarily on the operator immediately reporting incidents that indicate a possible massive contamination of the water network to health authorities - in particular complaints from the population, which are the only early-warning alerts in the case of waste water backflows.

A Waterborne Outbreak of Gastroenteritis with Multiple Etiologies among Resort Island Visitors and Residents: Ohio, 2004

The implementation of treated municipal water systems in the 20th century led to a dramatic decrease in waterborne disease in the United States. However, communities with deficient water systems still experience waterborne outbreaks. In August 2004, we investigated an outbreak of gastroenteritis on South Bass Island, Ohio, an island of 900 residents that is visited by >500,000 persons each year. To identify the source of illness, we conducted a case-control study and an environmental investigation. A case was defined as diarrhea in a person who traveled to the island during the period from May 1 through 30 September 2004 and became ill within 2 weeks after the visit. Healthy travel companions served as matched control subjects. We also performed an environmental assessment and extensive testing of island water sources. Among the 1450 persons reporting illness, Campylobacter jejuni, norovirus, Giardia intestinalis, and Salmonella enterica serotype Typhimurium were identified in 16, 9, 3, and 1 persons, respectively. We interviewed 100 case patients and 117 matched control subjects. Case patients were more likely to drink water on the island than control subjects (68% vs. 35%; matched odds ratio, 4.3; 95% confidence interval, 2.2-9.3). Sampling of ground water wells indicated contamination with multiple fecal microbes, including Escherichia coli, C. jejuni, Salmonella species, and Giardia species. Irregularities in sewage disposal practices that could have contaminated the underground aquifer were noted. The combined epidemiological and environmental investigation indicated that sewage-contaminated ground water was the likely source of this large outbreak. Long-term changes to the island's water supply and sewage management infrastructure are needed.

Identification of Cpgp40/15 Type Ib as the Predominant Allele in Isolates of Cryptosporidium spp. from a Waterborne Outbreak of Gastroenteritis in South Burgundy, France

Cryptosporidium sp. isolates from a waterborne outbreak of diarrhea in France were analyzed by PCR-restriction fragment length polymorphism analysis and sequencing of the Cpgp40/15 locus. Ninety-one percent of the isolates were Cryptosporidium hominis type Ib. The results of this study and those of studies of other outbreaks suggest that the type Ib allele is the predominant allele associated with waterborne cryptosporidiosis.

Calicivirus inactivation by nonionizing (253.7-nanometer-wavelength [UV]) and ionizing (gamma) radiation.

Noroviruses (previously Norwalk-like viruses) are the most common viral agents associated with food- and waterborne outbreaks of gastroenteritis. In the absence of culture methods for noroviruses, animal caliciviruses were used as model viruses to study inactivation by nonionizing (253.7-nm-wavelength [UV]) and ionizing (gamma) radiation. Here, we studied the respiratory feline calicivirus (FeCV) and the presumed enteric canine calicivirus (CaCV) and compared them with the well-studied bacteriophage MS2. When UV irradiation was used, a 3-log(10) reduction was observed at a fluence of 120 J/m(2) in the FeCV suspension and at a fluence of 200 J/m(2) for CaCV; for the more resistant phage MS2 there was a 3-log(10) reduction at a fluence of 650 J/m(2). Few or no differences were observed between levels of UV inactivation in high- and low-protein-content virus stocks. In contrast, ionizing radiation could readily inactivate MS2 in water, and there was a 3-log(10) reduction at a dose of 100 Gy, although this did not occur when the phage was diluted in high-protein-content stocks of CaCV or FeCV. The low-protein-content stocks showed 3-log(10) reductions at a dose of 500 Gy for FeCV and at a dose of 300 for CaCV. The inactivation rates for both caliciviruses with ionizing and nonionizing radiation were comparable but different from the inactivation rates for MS2. Although most FeCV and CaCV characteristics, such as overall particle and genome size and structure, are similar, the capsid sequences differ significantly, making it difficult to predict human norovirus inactivation. Adequate management of UV and gamma radiation processes for virus inactivation should limit public health risks.

Inactivation of caliciviruses.

The viruses most commonly associated with food- and waterborne outbreaks of gastroenteritis are the noroviruses. The lack of a culture method for noroviruses warrants the use of cultivable model viruses to gain more insight on their transmission routes and inactivation methods. We studied the inactivation of the reported enteric canine calicivirus no. 48 (CaCV) and the respiratory feline calicivirus F9 (FeCV) and correlated inactivation to reduction in PCR units of FeCV, CaCV, and a norovirus. Inactivation of suspended viruses was temperature and time dependent in the range from 0 to 100 degrees C. UV-B radiation from 0 to 150 mJ/cm(2) caused dose-dependent inactivation, with a 3 D (D = 1 log(10)) reduction in infectivity at 34 mJ/cm(2) for both viruses. Inactivation by 70% ethanol was inefficient, with only 3 D reduction after 30 min. Sodium hypochlorite solutions were only effective at >300 ppm. FeCV showed a higher stability at pH <3 and pH >7 than CaCV. For all treatments, detection of viral RNA underestimated the reduction in viral infectivity. Norovirus was never more sensitive than the animal caliciviruses and profoundly more resistant to low and high pH. Overall, both animal viruses showed similar inactivation profiles when exposed to heat or UV-B radiation or when incubated in ethanol or hypochlorite. The low stability of CaCV at low pH suggests that this is not a typical enteric (calici-) virus. The incomplete inactivation by ethanol and the high hypochlorite concentration needed for sufficient virus inactivation point to a concern for decontamination of fomites and surfaces contaminated with noroviruses and virus-safe water.

Bacterial indicators of faecal pollution of water supplies and public health: a review

Bacterial indicators of faecal pollution of water supplies and their significance to public health are reviewed in this paper, to highlight their levels of general acceptability and suitability as safeguards against health hazards associated with water supplies. Regular bacteriological analysis with the sole aim of detecting faecal coliform as a confirmation of faecal pollution, is shown to constitute a safeguard against health hazards arising from the consumption of faecally-polluted water. It is also shown that available indicators cannot be fully relied upon for total safeguard espericially as Cryptosporidium oocysts and Giardia cysts have been implicated in some water-borne outbreaks of gastroenteritis. Furthermore, there are still problems of confusing ecology, characterization and taxonomy, growth temperature in both temperate and hot climates, coupled with the fact that several non-classical indicators, e.g., Bifidobacterium, Bacteroides, Eubacterium , etc., have been found to be equally attractive as apparently reliable indicators. This confusing situation appears to have created considerable doubt on the general acceptability of classical indicators (e.g. coliforms, Streptococcus faecalis and Clostridum perfringens ), as safeguards against water-related infection. In perspective, further research on methods of detecting reliable indicators in addition to maintaining hygienic principles in homes, are recommended. KEY WORDS: Water Pollution, Bacterial indicators, General acceptability, Public Health. Global Jnl Medical Sciences Vol.2(2) 2003: 81-90

Waterborne outbreak of gastroenteritis in a religious summer camp in Norway, 2002.

In July 2002 an outbreak of acute gastroenteritis occurred in a camp facility in western Norway during a 10-day seminar, with around 300 guests staying overnight and several day-time visitors. Environmental and epidemiological investigations were conducted to identify and eliminate the source of the outbreak, prevent further transmission and describe the impact of the outbreak. Of 205 respondents, 134 reported illness (attack rate, 65%). Multivariate analysis showed drinking water and taking showers at the camp-site to be significant risk factors. Secondary person-to-person spread among visitors or outside of the camp was found. Norovirus was identified in 8 out of the 10 stool samples analysed. Indicators of faecal contamination were found in samples from the private untreated water supply, but norovirus could not be identified. This outbreak investigation illustrates the importance of norovirus as a cause of waterborne illness and the additional exacerbation through person-to-person transmission in closed settings. Since aerosol transmission through showering contributed to the spread, intensified hygienic procedures such as isolation of cases and boiling of water may not be sufficient to terminate outbreaks with norovirus.

Substrate specificity of the Norwalk virus 3C-like proteinase

The Norwalk Virus (NV) is the prototype strain of human caliciviruses that cause epidemic outbreaks of foodborne and waterborne gastroenteritis. These viruses do not grow in cell culture and the mechanisms of virus replication are obscure. The NV genome is a 7.7 kb ssRNA molecule that encodes three open reading frames (ORFs). The first ORF is a 1789 amino acid polyprotein that is processed into nonstructural proteins by a viral protease similar to the picornavirus 3C protease. Primary cleavage sites in the ORF1 polyprotein of two Norwalk-like viruses have been identified as QG dipeptides. We studied primary cleavage sites in the NV polyprotein and residues surrounding the scissile bond that are important in substrate recognition. A series of mutations were made at amino acids occupying positions implicated as important in cleavage site recognition for chymotrypsin-like viral proteases. We determined that effective processing at amino acid 398 to release the N-terminal p48 protein is necessary for proteolytic release of the p41 protein, that the P4 position N-terminal to the scissile bond is important for efficient processing, and that substitution of large hydrophobic residues were tolerated at this position. Finally, we defined the acidic residue of the 3CL pro catalytic site.

Concentration and detection of caliciviruses in water samples by reverse transcription-PCR.

Human caliciviruses (HuCVs) cause waterborne outbreaks of gastroenteritis. Standard indicators of a safe water supply do not adequately predict contamination of water by viruses, including HuCVs. We developed a method to concentrate and detect HuCVs in water samples by using a cultivable primate calicivirus (Pan-1) as a model. Viable Pan-1 was seeded in different types of water and then filtered with a 1MDS filter, eluted with beef extract (BE), and reconcentrated by polyethylene glycol (PEG) precipitation. The viruses in the final samples were tested by plaque assay or by reverse transcription (RT)-PCR following extraction of the RNA with Trizol. Pan-1 was more sensitive to high-pH treatment than poliovirus was; a pH 9.0 BE solution was found to recover 35% more viable Pan-1 than a pH 9.5 BE solution recovered. Pan-1 was recovered from small volumes of deionized, finished, ground, and surface waters at efficiencies of 94, 73, 67, and 64%, respectively, when samples were assayed after elution without further concentration. When larger volumes of water (up to 40 liters) were tested after elution and concentration with PEG, 38, 19, and 14% of the seeded Pan-1 were recovered from finished, ground, and surface waters, respectively. The limit of detection of Pan-1 by RT-PCR was estimated to be 0.75 to 1.5 PFU in 40 liters of finished water. This method may be adapted for monitoring HuCVs in drinking water and other types of water for public health safety.

Campylobacter epidemiology: an aquatic perspective

Members of the genus Campylobacter have established themselves as the most common human gastro-enteric pathogens throughout much of the developed world. The ubiquitous distribution of Campylobacter spp. in animal reservoirs and food products derived thereof make such vehicles primary risk factors in contracting campylobacteriosis. The contamination rates, identification of common pathogenic serotypes and extended survival of Campylobacter in surface waters illustrates the potential, but yet to be quantified, campylobacteriosis risk associated with untreated water. The existence and potential pathogenicity of viable but nonculturable forms of Campylobacter remains a contentious subject. Furthermore, the role of such forms in the epidemiology of Campylobacter related disease and their involvement in the large number of waterborne gastroenteritis outbreaks from which a disease agent cannot be isolated remains to be fully clarified. This article presents a survey of current perspectives with regard to the survival and epidemiology of Campylobacter spp. in natural water systems.

Epidemiological explanation of an outbreak of gastro-enteritis in Sweden in the absence of detailed microbiological information.

Waterborne gastroenteritis outbreaks have often gone undetected or been incompletely defined in terms of source and extent. Methods which allow detection or clarification of such events are therefore useful. We describe the methods used to detect and investigate such an outbreak. In autumn 1996 high school absence rates and the rate of parents absent from work to care for sick children suggested a health problem in a Swedish town which had a history of unexplained outbreaks of gastrointestinal disease. A systematic sample of 300 households was surveyed by post. Respondents represented 10% of the total population of the town. Questions concerning symptoms and exposures were included. The same questionnaire was used in a nearby town as a control. Sixty four percent of respondents reported an acute gastrointestinal illness during a two month period. Diarrhoea (90%) and abdominal pain (88%) were the most frequent symptoms among the sick. Two percent of those sick sought medical care. Exposures associated with disease were being a member of a large household, young age, and consumption of water from the community water supply. Attack rate showed a dose response relationship with increasing frequency of water consumption. The peak incidence of gastrointestinal illness occurred shortly after raw water quality control data had shown a rise in indicator bacteria. Further analysis, dividing those infected into groups according to when they became ill and whether they were the first member of their household to fall ill, supported the hypothesis of primary cases being infected from the water supply with some secondary person to person spread.

Outbreaks of food-borne and waterborne viral gastroenteritis.

Norwalk virus infection is the epidemiologic prototype for outbreaks of food-borne and waterborne gastroenteritis. Around the world, Norwalk virus and Norwalk-like viruses appear to be major causes of food-borne and waterborne illness. Assessment of the overall significance of viral agents to the epidemiology of food-borne and waterborne illness is hampered by the lack of surveillance throughout much of the world. In areas where food-borne and waterborne illness surveillance is conducted, outbreaks of viral gastroenteritis are underreported because of the lack of availability of routine laboratory services to confirm the viral etiology. Routine use of epidemiologic criteria as an alternative to laboratory confirmation will allow better assessments of the importance of viral gastroenteritis until effective laboratory methods can be widely implemented. Outbreaks of viral gastroenteritis have been propagated by contamination of water supplies, raw foods, and ill food handlers. Controlling an outbreak depends on identifying and removing the source of contamination. The demonstrated occurrence of person-to-person transmission and the likely occurrence of transmission of Norwalk-like viruses by aerosol make it necessary to evaluate the potential for transmission by food handlers and servers in every outbreak, regardless of primary source.

Outbreaks of food-borne and waterborne viral gastroenteritis.

Norwalk virus infection is the epidemiologic prototype for outbreaks of food-borne and waterborne gastroenteritis. Around the world, Norwalk virus and Norwalk-like viruses appear to be major causes of food-borne and waterborne illness. Assessment of the overall significance of viral agents to the epidemiology of food-borne and waterborne illness is hampered by the lack of surveillance throughout much of the world. In areas where food-borne and waterborne illness surveillance is conducted, outbreaks of viral gastroenteritis are underreported because of the lack of availability of routine laboratory services to confirm the viral etiology. Routine use of epidemiologic criteria as an alternative to laboratory confirmation will allow better assessments of the importance of viral gastroenteritis until effective laboratory methods can be widely implemented. Outbreaks of viral gastroenteritis have been propagated by contamination of water supplies, raw foods, and ill food handlers. Controlling an outbreak depends on identifying and removing the source of contamination. The demonstrated occurrence of person-to-person transmission and the likely occurrence of transmission of Norwalk-like viruses by aerosol make it necessary to evaluate the potential for transmission by food handlers and servers in every outbreak, regardless of primary source.

Elevated levels of immunoglobulin A to Giardia lamblia during a waterborne outbreak of gastroenteritis.

During an outbreak of diarrheal illness among residents of a trailer park in rural Vermont, 37 (30%) of 122 residents met the case definition of outbreak-related giardiasis. Convalescent-phase sera from 24 residents and 20 nonresident control subjects were tested by enzyme-linked immunosorbent assay for immunoglobulin G (IgG), IgM, and IgA antibodies to Giardia lamblia. Residents showed higher levels of parasite-specific antibody than did nonresident controls for IgG and IgA but not IgM. Nine residents with giardiasis had a higher median level of G. lamblia-specific IgA but not IgG or IgM than 15 healthy residents (0.61 versus 0.16 optical density units; P = 0.004). Moreover, parasite-specific IgA levels were higher in those consuming tap water than in those who did not (0.31 versus 0.08 optical density units; P = 0.03) and increased with increasing water consumption. Levels of serum antibody to G. lamblia, particularly IgA, may be useful in determining exposure to G. lamblia-contaminated water and illness from G. lamblia during waterborne outbreaks of diarrheal illness.

Waterborne Viral Gastroenteritis

In studying the causes of human gastroenteritis, electron microscopy and related techniques have led to the identification of new viral agents that had previously escaped detection by routine cell culture procedures. Efforts to characterize and study these agents further are currently being made by researchers in many areas of the world. Two of the best‐known agents, rotavirus and Norwalk virus, have been implicated in waterborne outbreaks of this illness. Another virus, the Snow Mountain agent, was first identified from the investigation of one waterborne gastroenteritis outbreak.