2009-2010 Drinking Water-associated Outbreak Surveillance Report: Selected Outbreak Descriptions

This table provides descriptions of selected outbreaks presented in the Surveillance for Waterborne Disease Outbreaks Associated with Drinking Water and Other Nonrecreational Water — United States, 2009–2010 (MMWR Weekly).

Descriptions of Selected Waterborne Disease Outbreaks Associated with Drinking Water, United States, 2009-2010

Month Year State/Jurisdiction in which outbreak occurred Etiology No. of cases (deaths) Description of outbreak
July 2009 Maine Hepatitis A 2 Two individuals stayed in an island vacation home during their infectious period with acute Hepatitis A virus (HAV). The well supplying drinking water to the home likely became contaminated following a septic system breach. Ingestion of the contaminated well water resulted in four additional HAV illnesses. Secondary transmission occurred among family members of one of the four cases, resulting in three infections, with one death. There was no known transmission of HAV to residents on the island. Environmental testing revealed HAV contamination of the indoor plumbing of the home and in the outdoor seepage of the septic system breach. Water samples from the home faucets tested positive for total coliforms and Escherichia coli. Control measures included prophylaxis with immune globulin and HAV vaccine for close contacts, compliance with environmental codes for the home septic system, letters sent to participants of a potluck where potential transmission was suspected, two community meetings to provide education about HAV and septic system and well testing and maintenance, and beach closure for shellfish harvesting until the house septic system was brought into compliance with local codes.
January 2010 Vermont Cryptosporidium sp. 34 Thirty-four people from four states became ill after drinking tap water at a vacation rental property. A drilled private well supplied drinking water to the property, and a point-of-use water filter was used. The type of filter and the type of treatment provided by the filter were not reported. A cohort study implicated consumption of the home tap water; twenty-two of 23 people who consumed the water became ill, and none of the three people who did not consume the water reported illness (RR = 7.5). The tap water tested positive for total coliforms and Escherichia coli.
April 2010 Missouri Escherichia coli O157:H7 28 Twenty-eight people became ill after participation in various activities at a recreational facility. Tap water samples collected from various locations in the facility tested positive for Escherichia coli and total coliforms. The facility was served by a well that had originally served a private residence and was classified as an individual water system; the well had subsequently been repurposed to serve multiple buildings in the facility. As a result of this outbreak investigation, the system was reclassified as a community water system, which falls under EPA regulatory authority. 
May 2010 Pennsylvania Legionella pneumophila serogroup 1 3 (1) This outbreak resulted in three cases of illness at a personal care home, with one death. Multiple deficiency categories were assigned to Legionella outbreaks for the first time in the 2009–2010 surveillance report to better describe factors contributing to these outbreaks; this outbreak illustrates the complex factors in public water systems and building plumbing that can give rise to Legionella amplification and cases of legionellosis. The outbreak investigation implicated Legionella in the building plumbing (deficiency 5A). Additionally, there was an interruption in disinfection of the normally chlorinated well water before it entered the building (deficiency 3). There was also a cross-connection between drinking and non-drinking water pipes resulting in backflow within the facility (deficiency 6). Further, heavy rains that occurred prior to the outbreak might have impacted the source water quality. Although it is uncertain which of these factors directly caused the outbreak, it is plausible that any could have contributed to disruptions in water quality that facilitated Legionella amplification within the plumbing system and the subsequent outbreak.
June 2010 California Norovirus 47 Forty-seven people became ill after eating at a restaurant. Stool samples from five ill individuals were tested; of these, four tested positive for norovirus. A case-control study implicated water and ice. No food items were associated with illness, and 100% of the cases consumed water and/or ice, compared with 33% of the controls. The restaurant’s water source was an unchlorinated well, and an environmental investigation revealed the facility had a recent septic system backup and a problem with the well cap. Tap water samples tested positive for total and fecal coliforms, indicating that fecal contaminants were present in the well water; the water was not tested for norovirus. The restaurant owner chlorinated the well, and subsequent water samples tested negative for total and fecal coliforms. 
July 2010 Montana Campylobacter jejuni  101 This outbreak, which resulted in 101 reported cases of illness, came to public health attention following an increase in clinic and emergency department visits for acute gastroenteritis and a subsequent increase in reporting of laboratory-confirmed Campylobacter infections. Case-patient interviews revealed that most had visited a lodge cafe in a resort area, which was served by two wells. After notification of the epidemiologic evidence surrounding the investigation, the owners voluntarily closed the cafe. Tap water from the cafe and other buildings, including cabins, tested positive for fecal coliforms and Escherichia coli, and a boil water order was instituted throughout the resort. Campylobacter was then detected from both wells. The wells were sited near a river (50 and 250-300 feet) and were relatively shallow (<50 feet deep). Because of the area’s topography and hydrogeology, the aquifer supplying the two wells was suspected to have been periodically under the influence of surface water. In addition, the septic system seepage pit might have contributed to well water contamination. The remediation steps suggested included drilling a new well to a depth of 120 feet sited away from sewage components that had the capacity for full-time chlorination. The resort also agreed to plan for a new septic system.

Descriptions of Selected Waterborne Disease Outbreaks Associated with Other Nonrecreational Water, United States, 2009-2010

Month Year State/Jurisdiction in which outbreak occurred Etiology No. of cases (deaths) Description of outbreak
June 2010 Nevada Giardia intestinalis 20 Twenty people became ill with giardiasis after visiting a golf course. Water used for golf course irrigation (i.e. did not originate from a drinking water system) was the most likely source of infection; golfer behaviors included using fingers to clean golf balls, dipping towels into non-drinking water, and using teeth to remove golf gloves. Recommendations following the outbreak included informing golfers that irrigation water is not drinking water and that equipment and ice chests are likely to be contaminated, labeling all non-drinking water sources (spigots) on the course, and sanitizing ice chests.  
July 2010 Michigan Legionella pneumophila serogroup 1 64 This outbreak resulted in 64 reported cases of illness, and the investigation implicated a cooling tower at a military facility. Molecular typing revealed that a Legionella pneumophila serogroup 1 clinical isolate from a case-patient matched an environmental sample from a cooling tower, by monoclonal antibody (MAb) subgrouping and sequence based typing (SBT). Additional epidemiologic evidence included a higher attack rate in the building that was close to the cooling tower compared to a building that was farther away.
November 2010 New York Legionella pneumophila serogroup 1 4 This outbreak, linked to four reported cases of illness, resulted from occupational exposure to contaminated water in mist from a cleaning device in an industrial facility. Proximity to a shredder, which was cooled using water, and a conveyer belt were suspected. All four ill individuals had a history of cigarette smoking and/or passive smoking exposure; all were hospitalized and were less than 50 years old (age information missing for one person). A previous case of illness in this facility occurred in a 22 year old, who was also a former smoker. Environmental testing revealed water used to cool the shredder and conveyor belt were positive for Legionella pneumophila serogroups 1 and 6, and an air sample was culture-negative for legionellae, but PCR-positive for Legionella spp. and Legionella pneumophila.