Investigation of Two Outbreaks of Gastroenteritis in Tr?i? in September 2011

Background

An outbreak of gastroenteritis of etiologically unspecified origin and an outbreak of Salmonellosis occurred simultaneously in September 2011 in Tržič. The purpose of the investigation of both outbreaks was to identify the most probable source and the mode of transmission and to implement preventive measures.

Methods

In two retrospective case-control studies, the association between gastroenteritis of etiologically unspecified origin or Salmonellosis and food from a restaurant or drinking tap water were tested by univariate and multivariate analysis. The subject in the first study was a sick person with salmonellosis, and the subject in the second study was a resident that developed diarrhoea and/ or vomiting. Cases were reported by doctors, and controls were selected from healthy persons who responded to the questionnaire.

Results

A person exposed to food from the restaurant had a 24.8 times higher odds ratio (univariate analysis OR 24.8, 95% CI 7.5 to 82.3, p <0.05; multivariate analysis OR 14.7, 95% CI 3.5 – 61.3, p <0.05) for salmonellosis than non-exposed. A resident exposed to tap water from specific water source had a 3.4 times higher odds ratio (univariate analysis of OR 3.4, 95% CI 2.2 to 5.1 is p <0.05, multivariate analysis of RO 2.9, 95% CI 1, 7 to 5.3, p <0.05), for gastroenteritis of unspecific etiology than non-exposed. The dose response relationship was also statistically significant.

Conclusion

Analytical cases - controls studies confirmed a causal relationship between salmonellosis and food from the specific restaurant and the causal relationship between gastroenteritis of etiologically unspecified origin and drinking tap water from specific water source. Salmonella enteritidis may have entered into the restaurant through tap water.     

Brote de gastroenteritis por el consumo de agua de suministro público causado por Shigella sonnei

Objective

To investigate a waterborne outbreak in the population of València d’Àneu (Lleida, Spain).

Methods

A cohort study of consumption of mains water, bottled water and spring water was carried out. The sample was obtained by telephone contact with all private numbers in the municipality. We surveyed 58.3% of the population census (105/180) for water consumption, number of glasses drunk daily and symptoms. The water supply in the municipal system was sampled, and the presence of Enterobacteriaceae in the stool samples of 10 patients was determined. The association of each type of water was studied with estimation of relative risks (RR) and 95% confidence intervals (95% CI).

Results

The overall attack rate was 64.8% (68/105). The epidemic curve was consistent with an exposure of 6 days. Consumption of public supply water was associated with gastroenteritis (RR = 4.2, 95% CI: 1.5-11.9). In addition, a dose-response relationship was found (χ² = 34.1; p <0.001). There was a higher risk of illness in consumers of 2-3 glasses per day (RR = 4.3; CI 95%: 1.9-9.9) and in those drinking more than three glasses per day (RR = 4.9; 95% CI: 2.2 -10.9). The chlorinator of mains water froze and stopped working. Six stool cultures were positive for Shigella sonnei.

Conclusions

A waterborne outbreak of S. sonnei was caused by contamination of the public water supply. Investigation of illegal dumping of wastewater was recommended. Municipalities should ensure proper disinfection systems and prevent spillage near deposits.     

Epidemiological analysis of a cluster within the outbreak of Shiga toxin-producing Escherichia coli serotype O104:H4 in Northern Germany, 2011

In May 2011 one of the worldwide largest outbreaks of haemolytic uraemic syndrome (HUS) and bloody diarrhoea caused by Shiga toxin-producing Escherichia coli (STEC) serotype O104:H4 occurred in Germany. One of the most affected federal states was Lower Saxony. We present the investigation of a cluster of STEC and HUS cases within this outbreak by means of a retrospective cohort study. After a 70th birthday celebration which took place on 7th of May 2011 among 72 attendants seven confirmed cases and four probable cases were identified, two of them developed HUS. Median incubation period was 10 days. Only 35 persons (48.6%) definitely answered the question whether they had eaten the sprouts that were used for garnishing the salad. Univariable analysis revealed different food items, depending on the case definition, with Odds Ratio (OR) > 1 indicating an association with STEC infection, but multivariable logistic regression showed no increased risk for STEC infection for any food item and any case definition. Sprouts as the source for the infection had to be assumed based on the results of a tracing back of the delivery ways from the catering company to the sprouts producer who was finally identified as the source of the entire German outbreak. In this large outbreak several case–control studies failed to identify the source of infection.     

Effect modification of the association between trihalomethanes and pancreatic cancer by drinking water hardness: Evidence from an ecological study

The objective of this study was to examine the relationship between total trihalomethanes (TTHM) levels in public water supplies and risk of pancreatic cancer and to determine whether calcium (Ca) and magnesium (Mg) levels in drinking water modify the effects of TTHM on risk to develop pancreatic cancer. A matched case-control study was used to investigate the relationship between the risk of death attributed to pancreatic cancer and exposure to TTHM in drinking water in 53 municipalities in Taiwan. All pancreatic cancer deaths in the 53 municipalities from 1998 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair matched to the cancer cases by gender, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each cancer case. Data on TTHM levels in drinking water were collected from Taiwan Environmental Protection Administration. Information on the levels of Ca and Mg in drinking water was obtained from the Taiwan Water Supply Corporation. The municipality of residence for cancer cases and controls was presumed to be the source of the subject's TTHM, Ca, and Mg exposure via drinking water. Relative to individuals whose TTHM exposure level<4.9 ppb, the adjusted OR (95% CI) for pancreatic cancer was 1.01 (0.85-1.21) for individuals who resided in municipalities served by drinking water with a TTHM exposure>4.9 ppb. There was no evidence of an interaction of drinking water TTHM levels with low Ca intake via drinking water. However, we observed evidence of an interaction between drinking water TTHM concentrations and Mg intake via drinking water. Our findings showed that the correlation between TTHM exposure and risk of pancreatic cancer is influenced by Mg in drinking water. Increased knowledge of the interaction between Mg and TTHM in reducing pancreatic cancer risk will aid in public policy making and standard setting.     

Efficacy of different pneumococcal conjugate vaccine schedules against pneumonia,hospitalisation, and mortality: Re-analysis of a randomised trial in The Gambia

Background

Pneumococcal conjugate vaccines (PCV) reduce disease due to Streptococcus pneumoniae. We aimed to determine the efficacy of different PCV schedules in Gambian children.

Methods

We reanalysed data from a randomised placebo-controlled trial. Infants aged 6–51 weeks were allocated to three doses of nine-valent PCV (n = 8718) or placebo (n = 8719) and followed until age 30 months. We categorised participants to compare: (a) a first dose at age 6 or 10 weeks, (b) intervals of 1 or 2 months between doses, and (c) different intervals between second and third doses. The primary endpoint was first episode of radiologic pneumonia; other endpoints were hospitalisation and mortality. Using the placebo group as the reference population, Poisson regression models were used with follow-up after the first dose to estimate the efficacy of each schedule and from age 6 weeks to estimate the incidence rate difference between schedules.

Results

Predicted efficacy in the groups aged 6 weeks (n = 2467, 154 events) or 10 weeks (n = 2420, 106 events) at first dose against radiologic pneumonia were 32% (95% CI 19–43%) and 33% (95% CI 21–44%), against hospitalisation 14% (95% CI 3–23%) and 17% (95% CI 7–26%), and against mortality 17% (95% CI −3 to 33%) and 16% (95% CI −3 to 32%) respectively. Predicted efficacy in the groups with intervals of 1 month (n = 2701, 133 events) or 2 months (n = 1351, 58 events) between doses against radiologic pneumonia were 33% (95% CI 20–44%) and 36% (95% CI 24–46%), against hospitalisation 15% (95% CI 5–24%) and 18% (95% CI 8–27%), and against mortality 17% (95% CI −2 to 33%) and 13% (95% CI −8 to 29%) respectively. Efficacy did not differ by interval between second and third doses, nor did the incidence rate difference between schedules.

Conclusions

We found no evidence that efficacy or effectiveness of PCV9 differed when doses were given with modest variability around the scheduled ages or intervals between doses.     

Sero-prevalence of mumps antibodies in subpopulations subsequently affected by a large scale mumps epidemic in Israel

Background and aims

Despite the high national vaccination coverage, a large outbreak of mumps occurred in Israel, in 2009-2010, with onset and heavy transmission in ultraorthodox Jewish communities and further country-wide spread. We examined the sero-prevalence of mumps antibodies in the subpopulations subsequently affected by this large mumps outbreak, compared with the general population.

Methods

The study was conducted in ultraorthodox Jewish communities, in Jerusalem district (N = 251), in Bnei Brak city in Tel Aviv district (N = 453), and in the general population (N = 1846), using residual sera of 1-20 year old subjects. Mumps IgG antibodies were measured using Enzygnost anti-parotitis virus IgG ELISA kit.

Results

Mumps sero-positivity was significantly lower in Jerusalem: 51.8% (95% CI 51.9-61.0), and Bnei Brak: 56.5% (95% CI 45.6-57.9), than in the general population: 68.1% (95% CI 66.0-70.2). Sero-positivity increased with age, however in Jerusalem it was substantially low (46%) in the age group 10-20 years. This age group comprised a significant portion of mumps patients in the 2009-2010 outbreak.

Conclusions

Low immunity levels, combined with overcrowding and social mixing, were the main predisposing factors of the enhanced epidemic transmission of mumps in the ultraorthodox Jewish communities and further country-wide spread.     

Cryptosporidiosis in Wisconsin: a case-control study of post-outbreak transmission.

During March-April 1993, an estimated 403000 residents of the 5-county greater Milwaukee, Wisconsin area developed cryptosporidiosis after drinking contaminated municipal water. Although the number of cases dropped precipitously after the implicated water plant closed on 9 April, cases continued to occur. To investigate risk factors for post-outbreak cryptosporidiosis, 33 Milwaukee-area residents who had laboratory-confirmed Cryptosporidium infection with onset of diarrhoea between 1 May and 27 June 1993 were interviewed by telephone. Of these, 28 (85%) had onset of diarrhoea during May, 12 (36%) had watery diarrhoea during the outbreak, and 5(15%) were HIV-infected. In a neighbourhood-matched case-control study, immunosuppression (matched odds ratio (MOR) not calculable, 95% confidence interval (CI) 3.0, infinity) and having a child less than 5 years old in the household (MOR = 17.0, CI 2.0, 395.0) were independently associated with infection. When persons who had diarrhoea during the outbreak were excluded, immunosuppression remained significantly associated with illness (MOR not calculable, CI 1.6, infinity). Cryptosporidium transmission continued after this massive waterborne outbreak but decreased rapidly within 2 months.     

Human papillomavirus vaccination and Pap testing profile in Manitoba,Canada

Background

Females who receive the human papillomavirus (HPV) vaccine may believe they are protected from developing cervical cancer and no longer require screening. Concern has also been expressed that vaccinated females are those that would be screened regularly. This study assesses the Pap testing behavior of vaccinated and non-vaccinated females.

Methods

For this population-based retrospective cohort study, vaccination and screening registries were linked for 3540 vaccinated females aged 15 years and over and 9592 matched non-vaccinated females. Conditional logistic regression, the Kaplan–Meier method and Cox regression were used to examine the association between vaccination and Pap testing.

Results

Vaccinated females were more likely to have had a Pap test within the year prior to the index date than non-vaccinated females (15–19 years old: OR = 1.38, 95% CI 1.20–1.59; 20+ years old: OR = 2.34, 95% CI 1.98–2.76). In the three-year period after the index date, vaccinated females had a significantly higher cumulative probability of having a Pap test (83.3%) than non-vaccinated females (66.1%). Females who had a Pap test within three years prior to the index date were more likely to have a Pap test after the index date (vaccinated: HR = 5.03, 95% CI 4.65–5.45; non-vaccinated HR = 3.97, 95% CI 3.70–4.24). Being vaccinated had a significant effect on Pap testing (15–19 years old: HR = 1.54, 95% CI 1.39–1.69; 20+ years old: HR = 1.87, 95% CI 1.52–2.31). 80.1% of vaccinated females who had a Pap test prior to the index date also had one subsequent to it, compared to 70.1% for non-vaccinated females. 41.1% of females had not been vaccinated nor had a Pap test.

Conclusion

The majority of vaccinated females continue to participate in screening, and do so at a higher rate than non-vaccinated females. Renewed efforts need to be made to include the large proportion of non–vaccinated, non–screened females in vaccination and/or screening.     

Outbreak of Salmonella javiana infection at a children's hospital.

OBJECTIVE: To determine the source of an outbreak of Salmonella javiana infection. DESIGN: Case-control study. PARTICIPANTS: A total of 101 culture-confirmed cases and 540 epidemiologically linked cases were detected between May 26, 2003, and June 16, 2003, in hospital employees, patients, and visitors. Asymptomatic employees who had eaten in the hospital cafeteria between May 30 and June 4, 2003, and had had no gastroenteritis symptoms after May 1, 2003, were chosen as control subjects. SETTING: A 235-bed academic tertiary care children's hospital. RESULTS: Isolates from 100 of 101 culture-confirmed cases had identical pulsed-field gel electrophoresis patterns. A foodhandler with symptoms of gastroenteritis was the presumed index subject. In multivariate analysis, case subjects were more likely than control subjects to have consumed items from the salad bar (adjusted odds ratio [aOR], 5.3; 95% confidence interval [CI], 2.3-12.1) and to have eaten in the cafeteria on May 28 (aOR, 9.4; 95% CI, 1.8-49.5), May 30 (aOR, 3.6; 95% CI, 1.0-12.7), and/or June 3 (aOR, 4.0; 95% CI, 1.4-11.3). CONCLUSIONS: Foodhandlers who worked while they had symptoms of gastroenteritis likely contributed to the propagation of the outbreak. This large outbreak was rapidly controlled through the use of an incident command center.     

Risk factors associated with parents claiming personal-belief exemptions to school immunization requirements: community and other influences on more skeptical parents in Oregon, 2006

Background and objectives

With vaccine-preventable diseases at record lows, few studies investigate rising parent-claimed exemptions to school immunization requirements. After finding exemption clusters in Oregon, we hypothesized that exemption risk factors may vary among communities. We surveyed parents to identify risk factors for exemptions and evaluated risk factor differences among communities with differing exemption rates.

Design

Retrospective cohort study, multi-staged, population-proportionate sampling.

Setting and participants

Parents of 2004-05 Oregon elementary school children (N = 2900).

Main outcome measure

Parent-reported exemption status.

Results

The response rate was 55%. Compared to vaccinators, exemptors were significantly more likely to have: strong vaccine concerns (weighted adjusted odds ratio (aOR) = 15.3, 95% CI 6.4-36.7); “vaccine-hesitant” concerns (aOR = 2.3; 95% CI 1.0-5.0); >1 childbirth(s) at a non-hospital, alternative setting (aOR = 3.6; 95% CI 1.6-8.0); distrust of local doctors (aOR = 2.7; 95% CI 1.0-7.5); reported chiropractic healthcare for their youngest school-age child (aOR = 3.9; 95% CI 1.8-8.5); and reported knowledge of someone with a vaccine-hurt child (aOR = 1.8; 95% CI 0.9-3.4). Exemptors were less likely to have “pro-vaccine” beliefs (aOR = 0.2; 95% CI 0.0-0.6) and less likely to report relying on print materials (aOR = 0.4; 95% CI 0.2-0.8).The strengths of association differed significantly for those with strong vaccine concerns and those reporting knowledge of someone with a vaccine-hurt child, depending on residence in exemption-rate areas, e.g., exemptors in medium-rate areas were more likely to have strong vaccine concerns (aOR = 13.5; 95% CI 5.4-34.0) than those in high-rate areas (aOR = 9.7; 95% CI 3.7-25.4).

Conclusions

Vaccine beliefs were important risk factors. That differing community-level exemption use modified the effects of several individual-level factors suggests that communities also influence parent decisions. Therefore, understanding community contexts and norms may be important when designing interventions.     

Outbreak of Norwalk virus in a Caribbean island resort: application of molecular diagnostics to ascertain the vehicle of infection

In 1998, an outbreak of gastroenteritis affected at least 448 persons including 122 staff at a resort hotel in Bermuda. A survey among staff indicated that gastroenteritis was associated with eating or drinking at the hotel (OR = 60, 95% CI = 2.4-15.1). Multiple specimens of drinking water had elevated faecal coliform levels and Escherichia coli present, suggestive of faecal contamination. Stools from 18 of the 19 persons with gastroenteritis that were tested were positive for genogroup-II Norwalk-like viruses (NLVs). RT-PCR analysis of a 31 specimen of water produced a genogroup-II NLV genome with a sequence identical to that of NLVs in the stools of three ill persons. This outbreak shows the value of new molecular diagnostics to link illness with a contaminated source through the use of sequence analysis. The risk of outbreaks such as these could be reduced in tourism dependent regions like Bermuda and the Caribbean by regular evaluation of data from the inspection and monitoring of drinking water supplies and waste water systems, by ensuring the chlorination of supplemental drinking water supplies and by establishing food-safety initiatives.     

Risk factors associated with typhoid fever in Son La province, northern Vietnam

Between July and December 2002, we undertook a hospital-based case-control study to identify risk factors associated with typhoid fever in Son La province, northern Vietnam. Among 617 suspected cases, 90 cases of typhoid fever were confirmed by blood or stool culture. One hundred and eighty controls (neighbours of typhoid cases matched for gender and age) were chosen. Participants were interviewed at home using a standardized questionnaire. Seventy-five per cent of cases were aged 10-44 years. No cases in patients aged less than 5 years were recorded in this study. In a conditional logistic regression analysis recent contact with a typhoid patient (OR = 3.3, 95% CI 1.7-6.2, P < 0.001), no education (OR = 2.0, 95% CI 1.0-3.7, P = 0.03) and drinking untreated water (OR = 3.9, 95% CI 2.0-7.5, P < 0.001) were independently associated with typhoid fever. Improving quality of drinking water must be a priority and health education strategies targeted at individuals with no schooling, and contacts of patients, would be expected to decrease the burden of typhoid fever.     

Carriage of diarrhoeagenic Escherichia coli by older children and adults in Accra, Ghana

Diarrhoeagenic Escherichia coli (DEC) were sought in stool specimens from 72 adults and children aged over 3 years, who presented with diarrhoea at a hospital in Accra, Ghana, and 72 matched controls. Only diffusely-adherent E. coli were significantly associated with disease in these older individuals (P = 0.029). We additionally tested 53 specimens from infants among whom DEC were collectively associated with disease (P = 0.012). Enteropathogenic, enterotoxigenic and enteroaggregative E. coli, the most commonly isolated pathotypes from infants with diarrhoea, were frequently recovered from healthy adults. Asymptomatic carriage of DEC by older individuals in Accra may place young children at risk for diarrhoea.     

Risk factors for pandemic (H1N1) 2009 seroconversion among adults, Singapore, 2009

A total of 828 community-dwelling adults were studied during the course of the pandemic (H1N1) 2009 outbreak in Singapore during June-September 2009. Baseline blood samples were obtained before the outbreak, and 2 additional samples were obtained during follow-up. Seroconversion was defined as a >4-fold increase in antibody titers to pandemic (H1N1) 2009, determined by using hemagglutination inhibition. Men were more likely than women to seroconvert (mean adjusted hazards ratio [HR] 2.23, mean 95% confidence interval [CI] 1.26-3.93); Malays were more likely than Chinese to seroconvert (HR 2.67, 95% CI 1.04-6.91). Travel outside Singapore during the study period was associated with seroconversion (HR 1.76, 95% CI 1.11-2.78) as was use of public transport (HR 1.81, 95% CI 1.05-3.09). High baseline antibody titers were associated with reduced seroconversion. This study suggests possible areas for intervention to reduce transmission during future influenza outbreaks.     

Emerging genotype (GGIIb) of norovirus in drinking water, Sweden

From May through June 2001, an outbreak of acute gastroenteritis that affected at least 200 persons occurred in a combined activity camp and conference center in Stockholm County. The source of illness was contaminated drinking water obtained from private wells. The outbreak appears to have started with sewage pipeline problems near the kitchen, which caused overflow of the sewage system and contaminated the environment. While no pathogenic bacteria were found in water or stools specimens, norovirus was detected in 8 of 11 stool specimens and 2 of 3 water samples by polymerase chain reaction. Nucleotide sequencing of amplicons from two patients and two water samples identified an emerging genotype designated GGIIb, which was circulating throughout several European countries during 2000 and 2001. This investigation documents the first waterborne outbreak of viral gastroenteritis in Sweden, where nucleotide sequencing showed a direct link between contaminated water and illness.     

Eight years of Legionnaires' disease transmission in travellers to a condominium complex in Las Vegas, Nevada

SUMMARY Travel is a risk factor for Legionnaires' disease. In 2008, two cases were reported in condominium guests where we investigated a 2001 outbreak. We reinvestigated to identify additional cases and determine whether ongoing transmission resulted from persistent colonization of potable water. Exposures were assessed by matched case-control analyses (2001) and case-series interviews (2008). We sampled potable water and other water sources. Isolates were compared using sequence-based typing. From 2001 to 2008, 35 cases were identified. Confirmed cases reported after the cluster in 2001-2002 were initially considered sporadic, but retrospective case-finding identified five additional cases. Cases were more likely than controls to stay in tower 2 of the condominium [matched odds ratio (mOR) 6·1, 95% confidence interval (CI) 1·6-22·9]; transmission was associated with showering duration (mOR 23·0, 95% CI 1·4-384). We characterized a clinical isolate as sequence type 35 (ST35) and detected ST35 in samples of tower 2's potable water in 2001, 2002, and 2008. This prolonged outbreak illustrates the importance of striving for permanent Legionella eradication from potable water.     

Microbiologic effectiveness of boiling and safe water storage in South Sulawesi, Indonesia

In Indonesia, where diarrhea remains a major cause of mortality among children <5 years, the government promotes boiling of drinking water. We assessed the impact of boiling on water quality in South Sulawesi. We surveyed randomly selected households with at least one child <5 years old in two rural districts and tested source and stored water samples for Escherichia coli contamination. Among 242 households, 96% of source and 51% of stored water samples yielded E. coli. Unboiled water samples, obtained from 15% of households, were more likely to yield E. coli than boiled samples [prevalence ratios (PR) = 2.0, 95% confidence interval (CI) 1.7–2.5]. Water stored in wide-mouthed (PR = 1.4, 95% CI = 1.1–1.8) or uncovered (PR = 1.8, 95% CI = 1.3–2.4) containers, or observed to be touched by the respondent's hands (PR = 1.6, 95% CI = 1.3–2.1) was more likely to yield E. coli. A multivariable model showed that households that did not boil water were more likely to have contaminated stored water than households that did boil water (PR = 1.9, 95% CI = 1.5–2.3). Although this study demonstrated the effectiveness of boiling in reducing contamination, overall impact on water quality was suboptimal. Future studies are needed to identify factors behind the success of boiling water in Indonesia to inform efforts to scale up other effective water treatment practices.     

Cyclosporiasis associated with imported raspberries, Florida, 1996

OBJECTIVES: Until 1995, infection with Cyclospora cayetanenis, a parasite that causes gastroenteritis, was diagnosed in the US primarily in overseas travelers; its modes of transmission were largely unknown. In 1995, 45 cases of cyclosporiasis were diagnosed in Florida residents who had no history of recent foreign travel, but an investigation could not pinpoint a source for the parasite. In 1996, a North American outbreak of cyclosporiasis resulted in more than 1400 cases, 180 of them in Florida. The authors investigated the 1996 Florida outbreak to identify the vehicle of transmission. METHODS: The authors conducted a matched case-control study in which each of 86 laboratory-confirmed sporadic cases was matched with up to four controls. They also investigated nine clusters of cases associated with common meals and attempted to trace implicated foods to their countries of origin. RESULTS: In the case control study, eating raspberries was strongly associated with cyclosporiasis (matched odds ratio = 31.9; 95% confidence interval [CI] 7.4, 138.2). In the cluster investigation, raspberries were the only food common to all nine clusters of cases; a summary analysis showed a strong association between consumption of raspberries and confirmed or probable cyclosporiasis (risk ratio = 17.6; 95% CI 1.9, 188.8). Guatemala was the sole country of origin for raspberries served at six of nine events. CONCLUSIONS: Guatemalan raspberries were the vehicle for the 1996 Florida cyclosporiasis outbreak. Cyclospora is a foodborne pathogen that may play a growing role in the etiology of enteric disease in this country as food markets become increasingly international.     

Risk reduction assessment of waterborne Salmonella and Vibrio by a chlorine contact disinfectant point-of-use device

Unsafe drinking water continues to burden developing countries despite improvements in clean water delivery and sanitation, in response to Millennium Development Goal 7. Salmonella serotype Typhi and Vibrio cholerae bacteria can contaminate drinking water, causing waterborne typhoid fever and cholera, respectively. Household water treatment (HWT) systems are widely promoted to consumers in developing countries but it is difficult to establish their benefits to the population for specific disease reduction. This research uses a laboratory assessment of halogenated chlorine beads treating contaminated water to inform a quantitative microbial risk assessment (QMRA) of S. Typhi and V. cholerae disease in a developing country community of 1000 people. Laboratory challenges using seeded well water resulted in log₁₀ reductions of 5.44 (±0.98 standard error (SE)) and 6.07 (±0.09 SE) for Salmonella serotype Typhimurium and V. cholerae, respectively. In well water with 10% sewage and seeded bacteria, the log₁₀ reductions were 6.06 (±0.62 SE) and 7.78 (±0.11 SE) for S. Typhimurium and V. cholerae, respectively. When one infected individual was contributing to the water contamination through fecal material leaking into the water source, the risk of disease associated with drinking untreated water was high according to a Monte Carlo analysis: a median of 0.20 (interquartile range [IQR] 0.017–0.54) for typhoid fever and a median of 0.11 (IQR 0.039–0.20) for cholera. If water was treated, risk greatly decreased, to a median of 4.1 × 10⁻⁷ (IQR 1.6 × 10⁻⁸ to 1.1 × 10⁻⁵) for typhoid fever and a median of 3.5 × 10⁻⁹ (IQR 8.0 × 10⁻¹⁰ to 1.3 × 10⁻⁸) for cholera. Insights on risk management policies and strategies for public health workers were gained using a simple QMRA scenario informed by laboratory assessment of HWT.