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.     

Shigellosis outbreak associated with swimming

In June 1982, an outbreak of gastrointestinal illness caused by Shigella sonnei occurred among residents of two counties in Oklahoma. A case-control study of cases and age and sex-matched controls showed an association with attendance at a southern Oklahoma lake (14/17 cases vs 3/17 controls, matched pair odds ratio [OR] 9/0, confidence interval [CI] 2.4-infinity). A survey of 85 persons who had visited the lake area showed that persons who had swum were more likely to have been ill with a gastrointestinal illness (50 per cent) than persons who had not swum (0 per cent); among those who had swum, illness was more frequent among those who reported having water in their mouths while swimming (62 per cent) than those who did not (19 per cent) (OR = 6.9, 95% CI = 2.2-21.5). No further primary lake-associated cases had onset of symptoms beyond two days of closing the reservoir. Swimming should be considered as a potential source of enteric infections.     

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.     

Waterborne giardiasis at a mountain resort: evidence for acquired immunity

In November 1981, an outbreak of waterborne giardiasis occurred at a popular ski resort in Colorado. Stratification of illness by consumption of municipal tap water showed a striking dose-response, with an attack rate of 42 per cent among persons who drank six or more glasses of water per day. Filtered water samples revealed Giardia cysts in specimens both before and after treatment, and several deficiencies were found in the water treatment facility. Residents who had lived in the area greater than 2 years had a lower attack rate for illness than short-term residents.     

An outbreak of Norwalk-like gastroenteritis associated with contaminated drinking water at a caravan park

Abstract: During the 1989 Christmas holiday period, a large outbreak of gastroenteritis occurred among persons staying at a caravan park in southern New South Wales. Review of local hospital records found that 77 per cent of patients presenting with infective diarrhoea between 29 December and 3 January had stayed at the caravan park. In a retrospective cohort study we compared rates of illness among caravan park patrons exposed to different water sources. Stools were tested for pathogens and convalescent sera for viral antibodies. Rain and reticulated river water sampled from the caravan park were tested for bacteria and viruses. Of 351 persons interviewed at the caravan park, 305 (87 per cent) reported an illness characterised by diarrhoea, vomiting and abdominal pain. Of 196 persons who used reticulated river water for drinking or ablutions, 175 (89 per cent) became ill compared with 47 of 72 persons (65 per cent) who did not use this water (relative risk 1.4, 95 per cent confidence interval 1.2 to 1.6). The outbreak was probably caused by a 27–28 nm small round structured virus found in the stool from one ill person. High levels of faecal coliforms in the reticulated river water and enterovirus in sediment samples suggest that the outbreak was caused by sewage contaminating the reticulated river water through a break in the pipe directly over the underground water tanks. To prevent such outbreaks, poor water and sewerage system layouts should be avoided and nonpotable water should be clearly labelled. Where feasible, all camping-ground water should stem from town supplies.     

An outbreak of cryptosporidiosis associated with an animal nursery at a regional fair.

Cryptosporidiosis is a common gastrointestinal illness that is transmitted from infected persons, animals, or contaminated water or food. This article reports on an outbreak of cryptosporidiosis associated with an animal nursery at an agricultural show held in northern Tasmania during October 2001. Eighty-one per cent of cases (38/47) notified to the Tasmanian Department of Health and Human Services over a 35 day period were interviewed to determine potential sources of infection. Eighty-one per cent of interviewed cases (29/36) reported that they had attended the agricultural show, and 75 per cent (27/36) reported contact with animals in the animal nursery. Cases occurring more than one incubation period after the agricultural show were significantly more likely to have had contact with someone else with diarrhoea (p<0.01). This is the first reported outbreak of cryptosporidiosis associated with an animal nursery in Australia. The outbreak demonstrates the importance of infection control policies and hygiene measures in the animal nursery setting.     

Epidemiologic investigation of a Yersinia camp outbreak linked to a food handler

In July 1981, an outbreak of gastroenteritis occurred at a summer diet camp. Of the 455 campers and staff, 35 per cent developed an illness characterized by abdominal pain, fever, diarrhea, and/or nausea and vomiting. A total of 53 per cent experienced abdominal pain. Seven persons were hospitalized, five of whom had appendectomies. Yersinia enterocolitica serogroup 0:8 was isolated from 37 (54 per cent) of 69 persons examined, including the camp cook and three assistants. An epidemiologic investigation demonstrated that illness was associated with consumption of reconstituted powdered milk and/or chow mein . Y. enterocolitica serogroup 0:8 was subsequently isolated from milk, the milk dispenser, and leftover chow mein . Information obtained during the investigation suggested that the Yersinia had been introduced by a food handler during food-processing procedures.     

An outbreak of Yersinia enterocolitica infections caused by contaminated tofu (soybean curd)

The authors investigated 50 Yersinia enterocolitica infections during an outbreak of illness due to contaminated tofu (soybean curd) in Washington State between December 15, 1981 and February 22, 1982. The most common clinical syndrome (36 patients) was gastrointestinal infection for which two patients underwent appendectomies and one a partial colectomy. Of the remaining 14 patients, six had extraintestinal infections, two had fever alone, and six were asymptomatic. The patients with enteric infections were younger (median age three years) than those with extraintestinal infections (median age 28 years). In a case-control study of enteritis patients, illness was associated with ingestion of one brand of tofu (p less than 0.01). Ninety-two per cent of patients with gastrointestinal infections and 33% with extraintestinal infections recalled having eaten the implicated product. Y. enterocolitica serotype O:8, the most common serotype isolated from patients, was also isolated from tofu and the plant's untreated spring water. There was little clinical or laboratory evidence of secondary spread to family members who did not eat tofu. The outbreak demonstrates the transmission of Y. enterocolitica from nature to man and the potential of "natural" foods as vehicles for environmental pathogens.     

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.     

A Norwalk-like virus outbreak on the Appalachian Trail

In May and June 1999, an outbreak of acute gastrointestinal illness occurred among long-distance hikers on the Appalachian Trail between Catawba and Troutville, Virginia. An investigation found that 45 out of 70 hikers had become ill within two days of arriving in Catawba, Virginia. Water samples were collected from a general store frequented by the hikers and from several nearby buildings and a popular all-you-can-eat restaurant. Symptoms were consistent with those caused by Norwalk-like viruses, and laboratory diagnosis detected Norwalk-like viruses in stool and serum specimens. People who consumed food items prepared at the general store were almost twice as likely to become ill as persons who did not consume those foods. Environmental sampling of water from the taps inside and outside the general store and from several surrounding establishments in Catawba found contamination by fecal coliform bacteria but not by Norwalk-like virus. Since several hikers reported illness prior to arriving at Catawba, person-to-person transmission of a highly contagious agent such as Norwalk-like virus could not be ruled out. Poor sanitation, scarce water supplies, and crowding can increase the risk of gastrointestinal illness among long-distance hikers.     

Contaminated roof-collected rainwater as a possible cause of an outbreak of salmonellosis.

Roof-collected rainwater is a common water source in subtropical regions and has not been associated with human illness. In Trinidad, the West Indies, a church group, attending a rural camp, developed gastrointestinal illness, caused by Salmonella arechevalata. This rare serotype was isolated from stool specimens of campers, foods eaten at the camp, and a water tap, which was supplied by a storage tank of roof-collected rainwater. The surface of the roof, used as water catchment, was covered with bird faeces. It is postulated that rainwater, falling on the roof, washed off animal excrement which contained S. arechevalata and led to the outbreak of salmonellosis through camper ingestion of contaminated food and water.     

Waterborne Gastroenteritis due to the Norwalk Agent: Clinical and Epidemiologic Investigation

An outbreak of gastroenteritis occurred at a Pennsylvania summer camp in July 1978. Symptoms included abdominal pain (81 per cent), nausea (72 per cent), and vomiting (53 per cent); upper respiratory infection symptoms occurred in 35 per cent of the campers. Illness was associated with consumption of five or more glasses of water or water-containing beverages. Stool cultures from affected persons were negative for bacterial pathogens; however, a fourfold or greater rise to the Norwalk agent was demonstrated in serum samples of three of three ill persons tested and in none of eight controls (p < .02). Campers ill during the first session who were also present during the second session did not become ill during the second session (p < .001). (Am J Public Health 1982; 72:72-74.)     

Traveler''s diarrhea at sea: two multi-pathogen outbreaks caused by food eaten on shore visits

In 1976 and 1981, two outbreaks of gastrointestinal illness aboard cruise ships occurred within 24 hours following onshore visits to Haiti and Mexico, respectively. Three hundred eighty-six of 600 (64 per cent) and 98 of 260 (38 per cent) passengers became ill following luncheons in Port-au-Prince, Haiti, and Cozumel, Mexico. No increase in illness was observed among those passengers who did not attend the onshore luncheons. In both outbreaks, unrefrigerated seafood dishes served at outdoor buffets were epidemiologically incriminated as the vehicles of transmission. Several species of Vibrion, Salmonella, and toxigenic Escherichia coli were recovered from stool specimens of ill passengers in both outbreaks. In addition, invasive Escherichia coli and Shigella were isolated from stool specimens of ill passengers who ate at the Haitian buffet. Previous investigations of outbreaks of gastrointestinal illness aboard cruise ships have implicated exposures on board as the source and have involved only a single pathogen.     

Dengue risk among visitors to Hawaii during an outbreak

Despite the high rates of dengue in many tropical destinations frequented by tourists, limited information is available on the risk for infection among short-term visitors. We retrospectively surveyed 4,000 persons who arrived in Hawaii during the peak of the 2001-2002 dengue outbreak and collected follow-up serologic test results for those reporting denguelike illness. Of 3,064 visitors who responded, 94 (3%) experienced a denguelike illness either during their trip or within 14 days of departure; 34 of these persons were seen by a physician, and 2 were hospitalized. Twenty-seven visitors with denguelike illness provided a serum specimen; all specimens were negative for anti-dengue immunoglobulin G antibodies. The point estimate of dengue incidence was zero infections per 358 person-days of exposure with an upper 95% confidence limit of 3.0 cases per person-year. Thus, the risk for dengue infection for visitors to Hawaii during the outbreak was low.     

Haemolytic-uraemic syndrome in Western Australia, 1980 to 1994

Abstract: A retrospective, population-based study of patients hospitalised with the haemolytic-uraemic syndrome in Western Australia from 1980 to 1994 was undertaken to describe the epidemiology of the disease in this state. We identified 41 patients. Episodes were commonest in children under five years of age (63.4 per cent) and were more frequent in females (58.5 per cent) than in males; only one Aboriginal patient was detected. More than 90 per cent of episodes had a gastrointestinal prodrome lasting from one to 22 days; in 47.6 per cent of these episodes patients had bloody diarrhoea. The average hospital stay was 26 days, and 63.4 per cent of patients required dialysis (mean 10 days). More than 20 per cent of patients developed chronic renal failure, 9.7 per cent died, two patients developed hypertension and one child became epileptic; three of the 10 patients over 16 years of age (30 per cent) died. The haemolytic-uraemic syndrome is potentially fatal, affects mostly young children, and is usually preceded by a gastrointestinal illness. Episodes can occur in common-source outbreaks but, with the exceptions of related cases in families, that appears not to have been so in Western Australia since 1980. There is a need for increased awareness of the haemolytic-uraemic syndrome to enhance prospects for earlier detection and better clinical outcomes. Improved public health surveillance is also needed to reduce the risks of the syndrome in the community.     

Norwalk Gastroenteritis Associated with a Water System in a Rural Georgia Community

An outbreak of acute gastroenteritis occurred during January 4–9, 1982, in a rural community in north Georgia. A systematic telephone survey revealed that 63% of persons living in homes served by the community water system had symptoms of acute gastroenteritis in contrast to 9% of persons in homes served by private wells or other sources (P < .001). A fourfold rise in antibody titer to the Norwalk virus occurred in 20 of 22 serum pairs obtained from ill persons. Fecal coliforms (> 16 MPN/100 ml) were detected in a spring which served as one water source for the community system. Surface runoff from a heavy rainfall, which preceded the outbreak, may have contaminated the system. Outbreaks of gastroenteritis should be promptly reported and investigated to facilitate corrective measures and to identify causative agents such as Norwalk virus.     

An outbreak of gastrointestinal illness associated with the consumption of escolar fish.

An outbreak of gastrointestinal illness occurred amongst attendees of a conference lunch in the Hunter area, New South Wales, in October 2001. A distinctive symptom reported by many ill persons was the presence of oily diarrhoea. The Hunter Public Health Unit investigated the outbreak by conducting a telephone interview of the cohort of conference attendees using a standard questionnaire. Twenty persons out of 44 attendees (46%) became ill following the conference. The median incubation period was 2.5 hours (range 1-90 hours). The most common symptoms reported were; diarrhoea (80%)-38 per cent of these reported oily diarrhoea; abdominal cramps (50%); nausea (45%); headache (35%) and vomiting (25%). For analyses, a case was defined as a person who developed oily diarrhea, or diarrhoea within 48 hours, or had at least two other symptoms of gastroenteritis within 6 hours, of the conference lunch. Seventeen persons had symptoms that met the case definition. None of the foods or beverages consumed were significantly associated with illness, however, all cases had consumed fish and none of those who did not eat fish (4 persons) became ill. Moreover, only 'fish' or 'potato chips' could explain a significant proportion of the illness. Analysis of the oil composition of the fish consumed was consistent with the known profile of the species marketed as 'escolar'. Among those who consumed fish the following potential risk factors did not have a significant association with the illness; Body Mass Index, age, health status and the amount of fish consumed. We concluded that consumption of fish within the marketing group escolar can cause severe abdominal cramping, nausea and vomiting, in addition to incontinent diarrhoea.     

Waterborne disease outbreaks, 1986-1988

From 1986 to 1988, 24 states and Puerto Rico reported 50 outbreaks of illness due to water that people intended to drink, affecting 25,846 persons. The protozoal parasite Giardia lamblia was the agent most commonly implicated in outbreaks, as it has been for the last 10 years; many of these outbreaks were associated with ingestion of chlorinated but unfiltered surface water. Shigella sonnei was the most commonly implicated bacterial pathogen; in outbreaks caused by this pathogen, water supplies were found to be contaminated with human waste. Cryptosporidium contamination of a chlorinated, filtered public water supply caused the largest outbreak during this period, affecting an estimated 13,000 persons. A large multistate outbreak caused by commercially produced ice made from contaminated well water caused illness with Norwalk-like virus among an estimated 5,000 persons. The first reported outbreak of chronic diarrhea of unknown cause associated with drinking untreated well water occurred in 1987. Twenty-six outbreaks due to recreational water use were also reported, including outbreaks of Pseudomonas dermatitis associated with the use of hot tubs or whirlpools, and swimming-associated shigellosis, giardiasis, and viral illness. Although the total number of reported water-related outbreaks has been declining in recent years, the few large outbreaks due to Cryptosporidium, Norwalk-like agent, Shigella sonnei, and Giardia lamblia caused more cases of illness in 1987 than have been reported to the Water-Related Disease Outbreak Surveillance System for any other year since CDC and the Environmental Protection Agency began tabulating these data in 1971.     

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.     

Factors contributing to the emergence of Escherichia coli O157 in Africa.

In 1992, a large outbreak of bloody diarrhea caused by Escherichia coli O157 infections occurred in southern Africa. In Swaziland, 40,912 physician visits for diarrhea in persons ages >5 years were reported during October through November 1992. This was a sevenfold increase over the same period during 1990-91. The attack rate was 42% among 778 residents we surveyed. Female gender and consuming beef and untreated water were significant risks for illness. E. coli O157:NM was recovered from seven affected foci in Swaziland and South Africa; 27 of 31 patient and environmental isolates had indistinguishable pulsed-field gel electrophoresis patterns. Compared with previous years, a fivefold increase in cattle deaths occurred in October 1992. The first heavy rains fell that same month (36 mm), following 3 months of drought. Drought, carriage of E. coli O157 by cattle, and heavy rains with contamination of surface water appear to be important factors contributing to this outbreak.