Gastroenteritis associated with accidental contamination of drinking water with partially treated water

Due to human error, drinking water supplied to a new housing estate in The Netherlands was contaminated with grey water. The cohort of 921 accidentally exposed households (area A) had a higher attack rate for diarrhoea (54.1%) than a non-exposed cohort of 1529 households from an adjacent area (B) (24%) (RR 2.3, 95% CI 1.9-2.7). Household water score showed a dose-response with illness, in both areas A and B. For each 1000 inhabitants, 19.8 cases in area A, 7.0 cases in control area B (RRAB 2.2, 95% CI 1.3-3.8) and 3.3 cases in a more distant control area C (RRAC 4.6, 95% CI 2.7-8.0) were diagnosed with gastroenteritis by their general practitioner. A gastroenteritis outbreak associated with consumption of contaminated drinking water was observed in the exposed area. The use of grey water was banned in 2003, with the exception of rainwater use for flushing toilets. The risk of rainwater use is currently being investigated.     

Breaks and maintenance work in the water distribution systems and gastrointestinal illness: a cohort study

BACKGROUND: During maintenance work or breaks on the water distribution system, water pressure occasionally will be reduced. This may lead to intrusion of polluted water-either at the place of repair or through cracks or leaks elsewhere in the distribution system. The objective of this study was to assess whether breaks or maintenance work in the water distribution system with presumed loss of water pressure was associated with an increased risk of gastrointestinal illness among recipients. METHODS: We conducted a cohort study among recipients of water from seven waterworks in Norway during 2003-04. One week after an episode of mains breaks or maintenance work on the water distribution system, the exposed and unexposed households were interviewed about gastrointestinal illness in the week following the episode. RESULTS: During the 1-week period after the episode, 12.7% of the exposed households reported gastrointestinal illness in the household, compared with 8.0% in the unexposed households [risk ratio (RR) 1.58, 95% confidence interval (CI): 1.1, 2.3]. The risk was highest in households with higher average water consumption. The attributable fraction among the exposed households was 37% in the week following exposure. CONCLUSION: Our results show that breaks and maintenance work in the water distribution systems caused an increased risk of gastrointestinal illness among water recipients. Better data on the occurrence of low-pressure episodes and improved registration of mains breaks and maintenance work on the water distribution network are needed in order to assess the public health burden of contamination of drinking water within the distribution network.     

Septic system density and infectious diarrhea in a defined population of children

One-quarter of U.S. households use a septic system for wastewater disposal. In this study we investigated whether septic system density was associated with endemic diarrheal illness in children. Cases--children 1 to < 19 years old seeking medical care for acute diarrhea--and controls resided in the Marshfield Epidemiologic Study Area, a population-based cohort in central Wisconsin. Enrollment was from February 1997 through September 1998. Study participants completed a structured interview, and septic system density was determined from county sanitary permits. Household wells were sampled for bacterial pathogens and indicators of water sanitary quality. Risk factors were assessed for cases grouped by diarrhea etiology. In multivariate analyses, viral diarrhea was associated with the number of holding tank septic systems in the 640-acre section surrounding the case residence [adjusted odds ratio (AOR), 1.08; 95% confidence interval (CI), 1.02-1.15; p = 0.008], and bacterial diarrhea was associated with the number of holding tanks per 40-acre quarter-quarter section (AOR, 1.22; 95% CI, 1.02-1.46; p = 0.026). Diarrhea of unknown etiology was independently associated with drinking from a household well contaminated with fecal enterococci (AOR, 6.18; 95% CI, 1.22-31.46; p = 0.028). Septic system densities were associated with endemic diarrheal illness in central Wisconsin. The association should be investigated in other regions, and standards for septic systems should be evaluated to ensure that the public health is protected.     

Contaminated drinking water in one town manifesting as an outbreak of cryptosporidiosis in another

In early 1992 we identified an outbreak of cryptosporidiosis in Oregon and sought to identify and control its source. We used a series of studies to identify risk factors for illness: (i) a case-control study among employees of a long-term-care facility (LTCF); (ii) a matched case-control study of the general community; (iii) a cohort study of wedding attendees; and (iv) a cross-sectional survey of the general community. Drinking Talent water was associated with illness in the LTCF (OR = 22.7, 95 % CI = 2.7-1009.0), and in the community (matched OR = 9.5, 95% CI 2.3-84.1). Drinking Talent water was associated with illness only among non-Talent residents who attended the wedding (P < 0.001) and in the community (RR = 6.5, 95 % CI 3.3-12.9). The outbreak was caused by contaminated municipal water from Talent in the absence of a discernible outbreak among Talent residents, suggesting persons exposed to contaminated water may develop immunity to cryptosporidiosis.     

An outbreak of hypervitaminosis D associated with the overfortification of milk from a home-delivery dairy.

OBJECTIVES. The purpose of the study was to identify cases of hypervitaminosis D caused by the inadvertent overfortification of milk from a home-delivery dairy and to identify risk factors for this illness. METHODS. Hospital discharge, laboratory, and state health department data were used to define, identify, and describe cases of hypervitaminosis D diagnosed in the exposed communities between January 1, 1985, and June 30, 1991. To identify disease risk factors, community-based sex- and age-matched controls were used in a case-control study. RESULTS. Of the 56 case patients identified, at least 41 were hospitalized; 2 died. The study included 33 case patients and 93 control subjects. Nineteen of the 33 case patients had been customers of the implicated dairy. Risk of illness rose with increasing consumption of the dairy's milk and was also associated with vitamin D supplement use, sunburn susceptibility, and cancer history. Accounting for these factors did not alter the association between drinking the dairy's milk and developing hypervitaminosis D. CONCLUSIONS. Overfortification of milk with vitamin D can lead to hypervitaminosis D, manifested by severe illness and death. The episode highlights the need for monitoring the fortification process and enforcing the upper limit for vitamin D addition to milk.     

Viruses in nondisinfected drinking water from municipal wells and community incidence of acute gastrointestinal illness

Background: Groundwater supplies for drinking water are frequently contaminated with low levels of human enteric virus genomes, yet evidence for waterborne disease transmission is lacking.Objectives: We related quantitative polymerase chain reaction (qPCR)-measured enteric viruses in the tap water of 14 Wisconsin communities supplied by nondisinfected groundwater to acute gastrointestinal illness (AGI) incidence.Methods: AGI incidence was estimated from health diaries completed weekly by households within each study community during four 12-week periods. Water samples were collected monthly from five to eight households per community. Viruses were measured by qPCR, and infectivity assessed by cell culture. AGI incidence was related to virus measures using Poisson regression with random effects.Results: Communities and time periods with the highest virus measures had correspondingly high AGI incidence. This association was particularly strong for norovirus genogroup I (NoV-GI) and between adult AGI and enteroviruses when echovirus serotypes predominated. At mean concentrations of 1 and 0.8 genomic copies/L of NoV-GI and enteroviruses, respectively, the AGI incidence rate ratios (i.e., relative risk) increased by 30%. Adenoviruses were common, but tap-water concentrations were low and not positively associated with AGI. The estimated fraction of AGI attributable to tap-water-borne viruses was between 6% and 22%, depending on the virus exposure-AGI incidence model selected, and could have been as high as 63% among children < 5 years of age during the period when NoV-GI was abundant in drinking water.Conclusions: The majority of groundwater-source public water systems in the United States produce water without disinfection, and our findings suggest that populations served by such systems may be exposed to waterborne viruses and consequent health risks.     

Internet use and epidemiologic investigation of gastroenteritis outbreak

In March 2000, a large outbreak of gastroenteritis occurred in a community where a regional computer network provides free Internet access for 42% of the households. We conducted an epidemiologic investigation using the Internet for data collection. Norovirus was identified in stool samples of nine patients but not in the municipal water supply. Of households with access to the network, 19% participated in the survey. The overall attack rate by household was 63%. Drinking water from the nonchlorinated community water system was associated with illness (relative risk [RR] 1.6; 95% confidence interval [CI] 1.1 to 2.2); drinking water only from a private well was associated with decreased likelihood of illness (RR 0.3; 95% CI 0.1 to 0.8). Data collection through the Internet was efficient. Internet surveys may become more common in epidemiologic investigations and have the potential to provide data rapidly, enabling appropriate public health action. However, methods should be developed to increase response rates and minimize bias.     

“Where we put little fish in the water there are no mosquitoes:” a cross-sectional study on biological control of the <Emphasis Type="Italic">Aedes aegypti</Emphasis> vector in 90 coastal-region communities of Guerrero,Mexico

Background

In the Mexican state of Guerrero, some households place fish in water storage containers to prevent the development of mosquito larvae. Studies have shown that larvivorous fish reduce larva count in household water containers, but there is a lack of evidence about whether the use of fish is associated with a reduction in dengue virus infection. We used data from the follow up survey of the Camino Verde cluster randomised controlled trial of community mobilisation to reduce dengue risk to study this association.

Methods

The survey in 2012, among 90 clusters in the three coastal regions of Guerrero State, included a questionnaire to 10,864 households about socio-demographic factors and self-reported cases of dengue illness in the previous year. Paired saliva samples provided serological evidence of recent dengue infection among 4856 children aged 3–9 years. An entomological survey in the same households looked for larvae and pupae of Aedes aegypti and recorded presence of fish and temephos in water containers. We examined associations with the two outcomes of recent dengue infection and reported dengue illness in bivariate analysis and then multivariate analysis using generalized linear mixed modelling.

Results

Some 17% (1730/10,111) of households had fish in their water containers. The presence of fish was associated with lower levels of recent dengue virus infection in children aged 3–9 years (OR 0.64; 95% CI 0.45–0.91), as was living in a rural area (OR 0.57; 95% CI 0.45–0.71), and being aged 3–5 years (OR 0.65; 95% CI 0.51–0.83). Factors associated with lower likelihood of self-reported dengue illness were: the presence of fish (OR 0.79; 95% CI 0.64–0.97), and living in a rural area (OR 0.74; 95% CI 0.65–0.84). Factors associated with higher likelihood of self-reported dengue illness were: higher education level of the household head (OR 1.28; 95% CI 1.07–1.52), living in a household with five people or less (OR 1.33; 95% CI 1.16–1.52) and household use of insecticide anti-mosquito products (OR 1.68; 95% CI 1.47–1.92).

Conclusions

Our study suggests that fish in water containers may reduce the risk of dengue virus infection and dengue illness. This could be a useful part of interventions to control the Aedes aegypti vector.

     

Norwalk-related viral gastroenteritis due to contaminated drinking water

An explosive outbreak of gastrointestinal illness clinically compatible with infection by an agent serologically related to Norwalk virus agent occurred in an elementary school in May 1978. Seroconversion by radioimmunoassay to the Norwalk antigen was noted in two of three ill persons, but no viral particles were identified in stool. Illness developed in 72% of students and teachers at the school, and 32% of household contacts of these ill persons. Of household contacts of persons exposed at school but not clinically ill, 11% developed illness. This value, however, was not statistically different from the level of illness observed concurrently in household contacts of students at an unaffected school nearby. Epidemiologic investigation implicated water as the mode of transmission. Average consumption of one or more glasses per day was strongly associated with illness (p less than 0.00000001). Among soccer team members with limited school contact, water consumption at the school was associated with a 14-fold greater risk of illness (p less than 0.000001). Drinking water was most likely contaminated by back-siphonage through a cross-connection between the school's well and septic tank. This contamination occurred approximately 24 to 36 hours before the outbreak developed.     

Microbial quality of water in rural communities of Trinidad.

A cross-sectional study was conducted in four rural communities of northeastern Trinidad to determine the microbial quality of water supply to households and that quality's relationship to source and storage device. Of the 167 household water samples tested, total coliforms were detected in 132 of the samples (79.0%), fecal coliforms in 102 (61.1%), and E. coli in 111 (66.5%). There were significant differences among the towns in the proportion of the samples contaminated with coliforms (P < 0.001) and E. coli (P < 0.001). Of 253 strains of E. coli studied, 4 (1.6%) were mucoid, 9 (3.6%) were hemolytic, and 37 (14.6%) were nonsorbitol fermenters. Of 69 isolates of E. coli tested, 10 (14.5%) were verocytotoxigenic. Twenty-eight (14.0%) of 200 E. coli isolates tested belonged to enteropathogenic serogroups. Standpipe, the most common water source, was utilized by 57 (34.1%) of the 167 households. Treated water (pipeborne in homes, standpipes, or truckborne) was supplied to 119 households (71.3%), while 48 households (28.7%) used water from untreated sources (rain, river/stream, or well) as their primary water supply. The type of household storage device was associated with coliform contamination. Water stored in drums, barrels, or buckets was more likely to harbor fecal coliforms (74.2% of samples) than was water stored in tanks (53.3% of samples), even after controlling for water source (P = 0.04). Compared with water from other sources, water piped into homes was significantly less likely to be contaminated with total coliforms (56.9% versus 88.8%, P < 0.001) and fecal coliforms (41.2% versus 69.8%, P < 0.01), even when the type of storage device was taken into account. However, fecal contamination was not associated with whether the water came from a treated or untreated source. We concluded that the drinking water in rural communities in Trinidad was grossly unfit for human consumption, due both to contamination of various water sources and during household water storage.     

The economic consequences of malaria for households: a case-study in Nepal

Increased attention has recently been paid to the impact of illness on the well-being of households in developing countries. This has been a particular theme in the case of malaria, but relatively little evidence is available on how households react to malaria and on its impact on expenditure and time allocation patterns. This paper reports the results of a study designed to investigate the economic consequences of malaria for households in Nepal. A household survey of malaria cases in two districts provided information on use of various sources of treatment, their cost to households, time lost by the person with malaria, the extent to which others inside or outside the household provided assistance with the normal work of the malaria patient, the time spent caring for a child with malaria and any financial losses associated with the malaria episode. Out-of-pocket expenditure on treatment differed greatly between the two districts, for reasons associated with the choice of public or private sources of treatment and the number of visits made per episode. The majority of households appeared to cope without great difficulty with the reduction in labour supply caused by a malaria episode, by drawing largely on the time of adult family members. Caution is advised in extrapolating the results to other situations, given the extent to which local factors are likely to influence the impact on households. Moreover, the findings relate to a situation where a malaria control programme is in place: a relatively greater impact per household would occur in the absence of control. However, it is argued that such surveys have value in informing health policy, particularly in relation to setting priorities and treatment policy.     

Self-reported illness and household strategies for coping with health-care payments in Bangladesh

Objective

To investigate self-reported illness and household strategies for coping with payments for health care in a city in Bangladesh.

Methods

A cluster-sampled probability survey of 1593 households in the city of Rajshahi, Bangladesh, was conducted in 2011. Multilevel logistic regression – with adjustment for any clustering within households – was used to examine the risk of self-reported illness in the previous 30 days. A multilevel Poisson regression model, with adjustment for clustering within households and individuals, was used to explore factors potentially associated with the risk of health-care-related “distress” financing (e.g. paying for health care by borrowing, selling, reducing food expenditure, removing children from school or performing additional paid work).

Findings

According to the interviewees, about 45% of the surveyed individuals had suffered at least one episode of illness in the previous 30 days. The most frequently reported illnesses among children younger than 5 years and adults were common tropical infections and noncommunicable diseases, respectively. The risks of self-reported illness in the previous 30 days were relatively high for adults older than 44 years, women and members of households in the poorest quintile. Distress financing, which had been implemented to cover health-care payments associated with 13% of the reported episodes, was significantly associated with heart and liver disease, asthma, typhoid, inpatient care, the use of public outpatient facilities, and poverty at the household level.

Conclusion

Despite the subsidization of public health services in Bangladesh, high prevalences of distress financing – and illness – were detected in the surveyed, urban households.     

Copper in drinking water, Nebraska, 1994

In 1993, the levels of copper (Cu) in much of Nebraska's drinking water exceeded the U.S. Environmental Protection Agency's (EPA) action level of 1.3 mg/L. To determine the association of copper with gastrointestinal (GI) illness in August 1994 the authors interviewed persons living in households with 1993 Cu levels > 3 mg/L (51 households), 2-3 mg/L (54 households), and < 1.3 mg/L (43 households). Cases were defined as persons who had experienced the rapid onset of vomiting or nausea with abdominal pain during the preceding two weeks. To validate their exposure index, the authors immediately resampled drinking water in the households of 25 cases and 27 controls matched for age. Reassessment in December 1994 of the exposure and case status of the original cohort showed no association between copper in drinking water in 1993 and case status in 1994. The risk of GI illness seemed no greater with Cu > 3 mg/L (RR = 1.03; 95% CI = 0.43, 2.49) or 2-3 mg/L (RR = 0.50; 95% CI = 0.18, 1.41) than with Cu < 1.3 mg/L. The 1993 Cu concentrations could not be reproduced in August 1994; resampling in December 1994 again showed no association between GI illness and Cu exposure (RR > 1.3-2.9 mg/L, < or = 1.3 mg/L = 0.25, 95% CI = 0.10, 0.64, and RR > or = 3.0 mg/L, < or = 1.3 mg/L = 0.36, 95% CI = 0.09, 1.49).     

Epidemic campylobacteriosis associated with a community water supply.

In May 1983, an estimated 865 cases of epidemic gastrointestinal disease occurred in Greenville, Florida. Surveillance of pharmacy sales of antidiarrheal medicines suggested that the outbreak was confined to Greenville and its immediate vicinity. Surveys demonstrated that the gastrointestinal illness attack rates inside and outside the city limits were 56 per cent (72/128) and 9 per cent (7/77), respectively (relative risk (RR) = 6.2); consumption of city water was associated with illness (RR = 12); and as water consumption increased, the attack rate also increased (p less than 0.001). Four adults were hospitalized and one outbreak-related case of Guillain-Barre' syndrome was identified. Campylobacter jejuni was isolated from specimens from 11 ill persons; serologic studies showed the development of Campylobacter-specific antibodies. Fecal coliforms were found in water samples, but Campylobacter was not recovered from water. The city water plant, a deep well system, had numerous deficiencies including an unlicensed operator, a failure of chlorination, and open-top treatment towers. Birds were observed perching on the open-top treatment tower. Of 38 birds trapped seven weeks later, 37 per cent harbored C. jejuni; however, plasmid and serotyping studies showed that strains were not the same as the common strain from ill persons. This outbreak suggests that water systems that are unprotected from contact with birds may become contaminated and a source of outbreaks of human campylobacteriosis.     

Diarrhoea episodes and treatment-seeking behaviour in a slum area of North Jakarta, Indonesia

Visits to household during a census in an impoverished area of north Jakarta were used for exploring the four-week prevalence of diarrhoea, factors associated with episodes of diarrhoea, and the patterns of healthcare use. For 160,261 urban slum-dwellers, information was collected on the socioeconomic status of the household and on diarrhoea episodes of individual household residents in the preceding four weeks. In households with a reported case of diarrhoea, the household head was asked which form of healthcare was used first. In total, 8,074 individuals (5%)--13% of children aged less than five years and 4% of adults--had a diarrhoea episode in the preceding four weeks. The two strongest factors associated with a history of diarrhoea were a diarrhoea episode in another household member in the four weeks preceding the interview (adjusted odds ratio [OR] 11.1; 95% confidence interval [CI] 10.4-11.8) and age less than five years (adjusted OR 3.4; 95% CI 3.2-3.5). Of the 8,074 diarrhoea cases, 1,969 (25%) treated themselves, 1,822 (23%) visited a public-health centre (PHC), 1,462 (18%) visited a private practitioner or a private clinic, 1,318 (16%) presented at a hospital, 753 (9%) bought drugs from a drug vendor, and 750 (9%) used other healthcare providers, such as belian (traditional healers). Children with diarrhoea were most often brought to a PHC, a private clinic, or a hospital for treatment. Compared to children, adults with diarrhoea were more likely to treat themselves. Individuals from households in the lowest-income group were significantly more likely to attend a PHC for treatment of diarrhoea compared to individuals from households in the middle- and higher-income groups.     

Control of endemic nosocomial legionnaires' disease by using sterile potable water for high risk patients.

In a setting where potable water is contaminated with Legionella pneumophila serogroup 1, we performed two case control studies. The first case control study consisted of 17 cases of nosocomial Legionnaires' disease (LD) and 33 control (the patients who were admitted to the ward where the case was admitted immediately before and after the case) subjects. Cases had a higher mortality rate 65% vs 12% (P less than 0.004); were more likely to have received assisted ventilation (P less than 0.00001); to have nasogastric tubes (P less than 0.0004) and to be receiving corticosteroids or other immunosuppressive therapy (P less than 0.0001). Based on the results of this study, sterile water was used to flush nasogastric tubes and to dilute nasogastric feeds. Only 3 cases of nosocomial LD occurred during the next year compared with 12 the previous year (P less than 0.0001). Nine cases subsequently occurred and formed the basis for the second case-control study. Eighteen control subjects were those patients admitted to the same unit where the case developed LD, immediately before and after the case. The mortality rate for the cases was 89% vs 6% for controls (P less than 0.00003). The only other significant difference was that cases were more likely to be receiving corticosteroids or other immunosuppressive therapy 89% vs 39% (less than 0.01). We hypothesized that microaspiration of contaminated potable water by immunocompromised patients was a risk factor for nosocomial Legionnaires' disease. From 17 March 1989 onwards such patients were given only sterile potable water. Only two cases of nosocomial LD occurred from June 1989 to September 1990 and both occurred on units where the sterile water policy was not in effect. We conclude that aspiration of contaminated potable water is a possible route for acquisition of nosocomial LD in our hospital and that provision of sterile potable water to high risk patients (those who are receiving corticosteroids or other immunosuppressive drugs; organ transplant recipients or hospitalized in an intensive care unit) should be mandatory.     

Norovirus outbreak associated with undercooked oysters and secondary household transmission

During December 2009, over 200 individuals reported gastrointestinal symptoms after dining at a North Carolina restaurant. An outbreak investigation included a case-control study of restaurant patrons, a secondary household transmission study, environmental assessment of the restaurant facilities and operations, and laboratory analysis of stool and food samples. Illness was primarily associated with consumption of steamed oysters (odds ratio 12, 95% confidence interval 4·8-28) and 20% (8/41 households) reported secondary cases, with a secondary attack rate of 14% among the 70 susceptible household contacts. Norovirus RNA was detected in 3/5 stool specimens from ill patrons; sequencing of RT-PCR products from two of these specimens identified identical genogroup II genotype 12 sequences. Final cooked temperatures of the steamed oysters were generally inadequate to inactivate norovirus, ranging from 21°C to 74°C. Undercooked contaminated oysters pose a similar risk for norovirus illness as raw oysters and household contacts are at risk for secondary infection.     

Modeling of methyl isothiocyanate air concentrations associated with community illnesses following a metam-sodium sprinkler application

BACKGROUND: A series of illnesses occurred in Earlimart, CA on November 13, 1999 following a metam-sodium sprinkler application to a potato field on the southern edge of the town. METHODS: Case information was obtained from direct interviews, from illness complaints filed with state or county agencies, or from illness reports filed by community physicians for 173 subjects. Air concentrations of the by-product methyl isothiocyanate (MITC) during the episode were estimated based upon the Industrial Source Complex Short-Term (ISC3) air dispersion model, estimates from prior metam-sodium monitoring studies, and data from weather stations in two adjoining communities. RESULTS: Weather station data indicated that the November 13th incident corresponded with a temperature inversion at approximately 5:00 p.m. and a shift in the direction of prevailing wind from northwest to southeast. On the edge of Earlimart, 1-hr time weighted average (TWA) MITC concentration estimates ranged from 0.5 to 1 ppm. Of the 173 subjects, 170 had MITC-compatible symptoms, including eye or upper respiratory irritation (77.6%), non-specific systemic symptoms (64.7%), and lower respiratory symptoms (20.0%). 78.2% were exposed within 0.5 miles of the northern edge of the treated field where average 1 hr MITC concentrations exceeded the 800 ppb ocular irritation threshold. CONCLUSIONS: ISC3 modeling is a useful means of evaluating MITC concentrations for illness episodes when industrial hygiene assessment is not possible.     

An outbreak of cryptosporidiosis associated with a resort swimming pool.

An outbreak of cyptosporidiosis occurred in late April 1993 among resort hotel guests which was temporally associated with, but geographically distant from, a massive waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, that occurred in late March and early April of 1993. A case-control study was performed among groups with members who reported illness and among a systemic sample of groups who stayed at the resort hotel during the risk period. Of 120 persons interviewed, 51 (43%) met the case definition. Swimming in the resort hotel''s pool was significantly associated with case status (OR = 9.8; 95% Cl 3.4, 29.7), as was consumption of ice from the hotel''s ice machines (OR = 2.3; 95% Cl 1.01, 5.2). When analysis was restricted only to laboratory-confirmed cases and controls, swimming pool use was the only risk factor significantly associated with illness (OR = 13.0; 95% Cl 2.6, 88.7). Following waterborne outbreaks of cryptosporidiosis associated with water supplies, swimming pools should be considered as possible ongoing sources for transmission regionally.