2011-2012 Drinking Water-associated Outbreak Surveillance Report: Selected Outbreak Descriptions

This table provides descriptions of selected outbreaks presented in Surveillance for Waterborne Disease Outbreaks Associated with Drinking Water — United States, 2011-2012 (MMWR Weekly).

Descriptions of Selected Waterborne Disease Outbreaks Associated with Drinking Water, United States, 2011-2012

Month Year State/Jurisdiction in which outbreak occurred Etiology No. of cases (deaths) Description of outbreak
April 2009* New York Legionella pneumophila serogroup 1 4 In 2012, a combination of molecular typing and epidemiologic methods allowed investigators to determine that community-associated cases of Legionnaire’s disease distributed over several years belonged to a single outbreak.  At least four ill individuals resided in a large apartment complex sharing the same water source; the  onset days ranged from 2009–2012. Three of the four individuals provided samples for culture (two with onset in 2009 and one with onset in 2012), and these cases were linked during a 2012 investigation that identified the same L. pneumophila PFGE pattern in all three.  In addition, the same PFGE pattern was identified in four water samples from shower faucets from the apartment complex in 2012.
February 2011 Pennsylvania Legionella pneumophila serogroup 1 22 (5) Twenty-two individuals were identified during a hospital investigation as having confirmed or probable Legionnaire’s disease. Twenty-four of 25 water samples from the hospital tested positive for L. pneumophila, although the hospital had a copper/silver ion system in place, with ion levels at or above recommendations for L. pneumophila control. A published report on this outbreak recommended a higher index of suspicion for L. pneumophila even when infection control systems are in place; publication available hereexternal icon.
May 2011 Maryland Legionella pneumophila serogroup 1 7 (1) Seven guests of a hotel and spa became ill with pneumonia, with onset days ranging from May through September, 2011. A variety of water exposures were considered in the investigation, including taking a shower at the hotel, using a hot tub and using the pool. Epidemiologic evidence could not implicate any one exposure.  The hotel had an unconventional water heating system, whereby municipal drinking water entering the premises was diverted through plastic tubing on the roof before entering two holding tanks in the hotel. L. pneumophila serogroup 1 was cultured from multiple locations throughout the system, including water entering the holding tanks from the solar heating pipes, within the holding tanks, and in hotel guest rooms. Pool and hot tub inspections before the outbreak revealed that the pool had sufficient residual disinfectant levels but the hot tubs did not; however, no Legionellae were found in any hot tub. Municipal water tested negative for L. pneumophila. The unique solar heating system might have supported L. pneumophila growth and contributed to contamination of the hotel water system.
June 2011 New Mexico Norovirus 119 An outbreak of GI illness occurred among 119 youth camp attendees. Two attendees provided stool samples for testing and both were positive for norovirus. The water source for the camp was a spring, and also tested positive for norovirus at the time of the investigation. This is the second reported norovirus outbreak to occur at this youth camp; the first occurred in 1999 and was also traced to contamination in the spring-fed water system, suggesting that deficiencies were not adequately addressed or recurred after the first outbreak.
June 2012 Alaska Giardia intestinalis 21 A local public health nurse notified the state that thirty people at a camp in Alaska were ill with gastrointestinal symptoms including nausea, diarrhea, and bloating. Four individuals who had been at the camp during the outbreak had positive Giardia stool specimens and 17 were treated presumptively for the parasite. One of the four Giardia-positive stool specimens also tested positive for Blastocystis hominis, an intestinal microorganism of unknown pathogenicity. Three sources of water serve the camp, including a spring, a well and a stream. Stream water was connected to the camp water system three days prior to the date of first illness onset. During the investigation, water from the spring and the stream tested positive for total coliforms and E. coli. Following the investigation, hand wash stations and clean water were set up for use in kitchens and bathrooms until the water system was cleaned. Water use from the spring and stream was discontinued. This is the first reported outbreak assigned an untreated surface water deficiency (deficiency classification 1) since 2005.
August 2012 Illinois Pantoea agglomerans 12 Twelve patients in the outpatient oncology clinic of a hospital developed Pantoea agglomerans bloodstream infections. Nine patient blood samples were confirmed to contain Pantoea and seven of nine (78%) had indistinguishable PFGE patterns. Although a case control study did not reveal any significant common exposures, all patients had received infusions at this clinic. An opened bottle of infusate used for one ill patient was culture-confirmed to contain the organism, while unopened bottles tested negative. A sink swab from the pharmacy clean room sink where the infusions were prepared also shared the PFGE pattern found in patient blood samples. Other strains of Pantoea were isolated from other areas of the clinic, including an ice machine. Residual chlorine levels in pharmacy and infusion room sinks were lower than the recommended level of 0.2 ppm. This is the first waterborne disease outbreak in a healthcare setting caused by Pantoea that has been reported to CDC’s Waterborne Disease and Outbreak Surveillance System (WBDOSS). All waterborne disease outbreaks occurring in healthcare facilities can be reported to WBDOSS.
August 2012 Utah Giardia intestinalis 28 Twenty-eight individuals who lived on the same street in the same neighborhood reported gastrointestinal illness within a seven-week period. Stool samples from five individuals were positive for G. intestinalis. In the month prior to the first case illness onset, the neighborhood’s drinking water distribution system transitioned from one public water system to another, which likely caused low pressure in the neighborhood distribution system. The change in water pressure temporarily allowed contaminated water to flow into the drinking water system. The source of non-potable water was a previously unknown cross-connection between the drinking water system and a secondary irrigation water system. The cross-connection was fixed, and no additional illnesses were reported.
August 2012 Wisconsin Norovirus Genogroup I GI_2 19 Nineteen attendees of a wedding held at a banquet facility became ill with GI symptoms. A case control study revealed a 70% attack rate among attendees exposed to tap water and a 21% attack rate among unexposed attendees (odds ratio 8.75, 95% CI: 2.03–37.67). Three attendees’ stool samples tested positive for norovirus, as did samples of faucet tap water and septic system wastewater. The water source for the transient noncommunity water system that served the facility was an older well that did not meet recent standards for well depth. The owner was unaware of and had not maintained the facility’s septic system. This resulted in sewage leaching from the septic system into the well area prior to the outbreak. The facility owner was required to dig a new deeper well and install a new septic system.
October 2012 Colorado Propylene glycol suspected 26 Twenty-six individuals ill with GI, skin or eye symptoms shared a common exposure to water in a medical office building. Investigators suspected exposure to chemical contamination in the building’s drinking water system via ingestion, inhalation, and contact. An investigation revealed that valves inadvertently left open for 12 hours created a cross-connection between the building’s HVAC water system and drinking water system.  No clinical specimens were tested, however samples from the HVAC system and drinking water system (i.e. bathroom sink) were tested and all contained propylene glycol.

*The first ill cases were identified in 2009, and were linked by molecular subtyping in 2012 to additional ill individuals living in the same apartment complex with onset dates in 2011 and 2012.