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Appendix B

Descriptions of Selected Waterborne Disease Outbreaks Associated with Drinking Water, Water Not Intended for Drinking, and Water of Unknown Intent




which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Bacteria February 2006 Indiana Campylobacter spp. 32 Thirty-two county residents who developed gastrointestinal illness were included in a case-control study that implicated municipal water as the source of infection. Seven of nine people who provided stool specimens tested positive for Campylobacter species; and routine water samples from the treatment facility tested positive for total coliforms and Escherichia coli at the time of the outbreak. The investigation determined that a chlorinator had malfunctioned before the outbreak, resulting in inadequate chlorination of the water supply, and that cross-contamination also might have occurred when a new water main was pressure-tested with non-potable water. May 2005 Oregon Escherichia coli O157:H7, 60 Attendees of an outdoor school program at a camp developed C. jejuni, and E. coli O145 gastrointestinal illness with a median duration of four days. Stool samples were collected from 57 cases. Nine persons tested positive for E. coli O157:H7, three persons tested positive for C. jejuni, two persons tested positive for E. coli O145; and three persons tested positive for both E. coli O157:H7 and C. jejuni. The camp was required to upgrade the surface water-treatment system, which was suspected of providing inadequate treatment after heavy rainfall conditions. Raw water tested positive for fecal coliforms and E. coli approximately 1 week after the first case-patient became ill. May 2005 South Dakota Legionella pneumophila 18 (1) Eighteen confirmed cases of Legionnaires’ disease were reported serogroup 1 over a 5-month period in Rapid City, South Dakota. An investigation, including a case-control study and environmental sampling, was conducted. A small, decorative fountain lacking obvious aerosol-generating capacity was implicated. Clinical and environmental L. pneumophila serogroup 1 Benidorm isolates had identical sequence-based typing (SBT) patterns. (Source: O’Loughlin RE, Kightlinger L, Werpy, M, et al. Restaurant outbreak of Legionnaires’ disease associated with a decorative fountain: an environmental and case control study. BMC Infect Dis 2007;7:93). April 2006 Texas L. pneumophila serogroup 1 10 (3) Ten confirmed cases of Legionnaires’ disease, diagnosed by urine antigen and culture, were reported during spring 2005 after exposure to a hospital in San Antonio, Texas. The potable hot water supply of the newly constructed and recently opened inpatient building was determined to be the most likely source of the outbreak. Multiple L. pneumophila serogroup 1 strains were identified from environmental isolates taken from the hospital building; one previously unreported environmental strain matched a case-patient isolate. May 2002 Louisiana Pseudomonas aeruginosa 27 Thirty-eight employees at a cardboard box manufacturing facility were surveyed regarding recent dermatologic symptoms. Twenty-seven employees reported rashes that were suspected to be work-related and were consistent with P. aeruginosa infection. The facility had recently switched to a closed-water system. Water used in manufacturing processes and cleaning was treated and re-used as plant process water. Water samples from multiple sites using this water contained high concentrations of P. aeruginosa. Contributing factors noted from the water samples included elevated water temperatures, high organic content, elevated pH levels and varying disinfectant levels. The observation was made that certain areas of the water system were accessed substantially less frequently than others and that the ability of Pseudomonas to produce biofilms in hoses or pipes might have limited the effectiveness of the treatment methods. (Source: Hewitt DJ., et al. Industrial Pseudomonas folliculitis. Am J Ind Med 2006; 49:895–9).



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Viruses July 2006 North Carolina Hepatitis A 16 Private property owners allowed travelers to stay on their property and provided drinking water for public use. The drinking water source for the house and the camping area and the water supply for a limited amount of fruits and vegetables was a spring that the owner had excavated. Water was directed into a plastic reservoir above the spring. Untreated water was pumped to the house through a series of pipes and delivered to the downhill camping area through an overflow hose. Water from a spigot from outside the house tested positive for fecal coliforms, E. coli, and hepatitis A. The septic tank located directly upstream from the spring was considered a possible source of water contamination. July 2006 Maryland Norovirus G1 148 Attendees of a camp developed gastrointestinal illness. Participants were from England, Canada, Australia, Sweden, and the United States (i.e., California, Connecticut, Delaware, Indiana, Illinois, Massachusetts, Maryland, Michigan, New Jersey, New York, and Pennsylvania). Ten persons submitted stool samples, eight of which tested positive for norovirus G1. General concerns included toilet facilities with plumbing deficiencies and limited handwashing stations throughout the camp. The water distribution system did not contain a detectable level of chlorine. Nine of ten water samples from garden hoses used to provide drinking water contained total coliforms and E. coli. Well construction deficiencies were noted (e.g., absence of backflowprevention devices on the pool bath house water heaters and on water distribution lines to the latrines). The well storage tank and latrine wastewater samples contained Norovirus G1; tracer dye added to latrines was detected in the well. Parasites August 2005 California Giardia intestinalis 3 A child’s condition was diagnosed as laboratory-confirmed giardiasis, and a sibling and parent had clinically compatible symptoms. Canal water was piped into a private residence and used for bathing, dishwashing, housecleaning and laundry. Accidental ingestion of contaminated canal water was suspected. May 2006 Colorado G. intestinalis 6 Participants in a school trip to a state park became ill with gastrointestinal symptoms after consuming inadequately treated river water that was not intended for drinking. Treatment methods included the addition of iodine; filtration; and boiling. No one treatment method was used by the entire group (n=26) and variations in practice were observed among individuals who used each treatment method. Mixed Agents June 2006 Wyoming Norovirus G1, Norovirus G2, 139 Attendees of four week-long camps at a seasonal camp site experienced C. jejuni gastrointestinal illness. Investigators concluded that the camp’s two wells, which were drilled into fractured rock aquifers, may have been contaminated by raw sewage released from the main septic system. Water from the wells repeatedly tested positive for fecal and total coliforms; a septic tank sample tested positive for Norovirus G1 and G2. The main tank was documented as poorly located, at capacity and not meeting the state’s recommended standards for size or type of construction at the time of the outbreak. Well water was not filtered or chlorinated prior to consumption. (Source: CDC, Gastroenteritis among attendees at a summer camp—Wyoming, June-July 2006. MMWR 2007;56(15):368-370)



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Unidentified August 2006 New York Norovirus suspected 16 Visitors to a bed and breakfast, the owner and his daughter, developed gastrointestinal illness. The incubation period and duration of illness and symptoms were consistent with norovirus infection. The bed and breakfast had its own well and onsite wastewater disposal system, which were located in close proximity. A well water sample was positive for E. coli and might have been contaminated from a poorly maintained, leaking sewage system used by nearby cottages. Year-round residents used onsite septic systems or alternate disposal methods for wastewater when the seasonal system was turned off. The geology of the area was primarily fractured bedrock; contamination of the well likely resulted from waste that was released by the leaking seasonal sewage system or onsite wastewater systems, which then traveled through the rock until it reached the groundwater supply.

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Date last reviewed: 9/4/2008

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