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Appendix B

Descriptions of Selected Waterborne Disease and Outbreaks Associated with Recreational Water Use




State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Bacteria July 2005 Wyoming Campylobacter jejuni 6 Two families celebrated a holiday weekend together at a private residence. A small pool was set up for the adults and treated with a jug of bleach. A fill-and-drain pool (kiddie pool) was set up for the children and filled with untreated well water. A dog known to roll around in cow feces might have introduced fecal matter into the children’s pool. Five children, ranging from ages 13 months–8 years, and one adult developed gastrointestinal illness. Stool specimens from two of the children tested positive for Campylobacter. July 2005 California Leptospira spp. 3 Three men became ill and were diagnosed with laboratory-confirmed leptospirosis after removing brush and picking berries in a stream near their homes. The stream was very low and slow-flowing at the time of exposure. November 2005 Florida Leptospira spp. 43 Racers from approximately 30 U.S. states and two Canadian provinces were exposed to surface water from multiple sources, including creeks, swamps, and a river during an endurance race. In all, 192 (96%) of the racers were interviewed to collect information about exposures and signs and symptoms of illness. Mean incubation times were similar for suspected cases (12.8 days) and confirmed cases (13.5 days). The most common symptoms reported were fever (100%), headache (91%), chills (69%), sweats (68%), and muscle/joint pain (68%). Swallowing river and swamp water and being submerged were significantly associated with developing illness. January 2006 Florida Legionella 11 (1) Eleven persons became ill (3 confirmed Legionnaires’ disease and pneumophila serogroup 1 eight atypical pneumonia cases) after staying at a hotel. A case-control study was conducted and revealed that only exposure to the hotel’s indoor spa was a significant risk factor for developing illness. Environmental samples did not yield Legionella. However, several deficiencies were noted during the investigation, including suboptimal water temperatures and stagnation and sediment within the hot-water system. Bromine levels in the indoor spa were measured at 0.5 ppm at the time of investigation. January 2006 Illinois Legionella spp. 43 (1) Forty-three persons became ill (three confirmed Legionnaires’ disease and 40 Pontiac fever cases) following a hotel stay. A retrospective cohort study was conducted; exposure to the pool area was a significant risk factor for developing illness. L. pneumophila and L. maceachernii were isolated from water samples of both the pool and spa. No disinfectant residual was found in the pool or spa water. July 2006 California Shigella sonnei 9 Five families attended a party at a private residence. A fill-and-drain pool was filled with tap water with no additional treatment. Shigella sonnei was isolated from stool samples submitted by six attendees. A retrospective cohort study revealed a significant association between pool use and subsequent illness.



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Viruses May 2006 Wisconsin Norovirus 18 A total of 18 persons developed gastrointestinal illness after using a hotel swimming pool and spa; three patients’ stool specimens tested positive for norovirus. A case-control study showed a significant association between spa and/or pool use and illness. The pool had a high bather load, and an ill person had used the pool. Water testing records revealed inadequate disinfection during the time of suspected exposure. The hotel was advised to close the facilities and either hyperchlorinate or drain and refill them. Parasites June 2005 Florida Cryptosporidium spp. 47 This outbreak affected persons who played in or attended a youth sports tournament. Two teams with players who had gastrointestinal illness stayed in the same hotel. Although no pool water was tested for Cryptosporidium, swimming was the only risk factor significantly associated with illness. As a result of the investigation, the hotel was advised to keep daily maintenance logs for the swimming area. June 2005 New York C. hominis 2,307 An outbreak of gastrointestinal illness was traced to a water park with an interactive fountain. Stool samples for 495 of 572 people were positive for Cryptosporidium spp. Typing of 147 isolates identified them as C. hominis, indicating human contamination. The venue used chlorine and rapid sand filtration. Water samples collected from two tanks on three dates in mid-August contained C. hominis oocysts. C. hominis oocysts were also identified in a water filter and effluent from a sewer pump station. Polymerase chain-reaction tests were conducted on one water sample from each tank. The samples both contained 150 oocysts/L. Investigators determined that multiple factors contributed to the outbreak, including an inadequate recirculation design in which some water bypassed treatment and filtration as a result of the demand of the fountain. July 2005 Oregon C. parvum 20 A cohort study was conducted after two confirmed and 15 suspected cases of cryptosporidiosis were reported to a local health department. Gastrointestinal illness was epidemiologically linked with swimming in a pool at a membership club. A child with laboratory-confirmed cryptosporidiosis swam in the pool during the days that water contamination was suspected to have occurred. Control measures were quickly implemented and included hyperchlorination at the membership club pool, hyperchlorination of area public pools, and posting of signs at multiple pools to discourage swimming by ill individuals; prevention messages were disseminated by local media. July 2005 Massachusetts Giardia intestinalis 11 An outbreak at an athletic club implicated three outdoor pools (one adult pool and two children’s pools) with a shared filtration system. All 11 cases were laboratory confirmed. Although not observed, the occurrence of a fecal accident was strongly suspected. Records did not indicate that disinfectant levels were adjusted or that the pools were closed when chlorine readings were below recommended levels in early August. A water sample taken during the investigation revealed indicator bacteria (coliforms and E. coli) levels above allowable limits. July 2005 Oklahoma Naegleria fowleri 2 (2) Postmortem clinical specimens from two boys who died several days after they became ill indicated that they were infected with N. fowleri. Although both of the boys had spent time at a local water park before becoming ill, at least one child went swimming in untreated, stagnant water near his home before becoming ill. The boys’ homes were not far apart from each other. Water samples from a local creek and the water park’s spray deck were collected in July and August, respectively. Testing of cultures from both locations did not detect N. fowleri. PCR testing of the creek water was also negative. Water testing revealed temperatures >95°F (35°C) at both locations.



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO August 2005 Ohio C. hominis 523 A large, communitywide cryptosporidiosis outbreak affected 747 persons in Ohio. Recreational water exposure was associated with 70% (523/747) of the cases. This outbreak was linked by time and proximity to a cryptosporidiosis outbreak in Kentucky. Six pools were implicated as a source of exposure to contaminated water. More than 300 stool samples tested positive for Cryptosporidium. CDC performed additional molecular characterization of the Cryptosporidium isolates from one pool filter sand sample from the water park and seven clinical stool specimens; the subtype of the isolates of six of the stool specimens matched the pool filter sample’s isolate. July 2006 California Cryptosporidium spp. 16 This outbreak was initially detected by a laboratory-based active cryptosporidiosis surveillance system. Some of the case-patients shared a common exposure at a public park with an interactive fountain. A 10 L sample from the fountain system contained 137 oocysts/L and had a chlorine residual of 0.9 ppm. The fountain used a sand filtration system that was not designed to remove Cryptosporidium spp. and did not have an automated disinfection system. Similar public fountains in the area were closed if they had inadequate filtration and disinfection. Ill children were restricted from attending school and daycare to limit possible person-to-person transmission. July 2006 Illinois C. hominis 65 Attendees of a private day camp developed gastrointestinal illness that was epidemiologically linked to recreational swimming at a private day camp pool and at a public outdoor water park. A total of seven laboratory-confirmed cases and 58 probable cases were identified. PCR detected C. hominis in stool specimens from three patients. An inspection of the day camp pool revealed poor water quality, unsanitary pool facilities and an absence of policies intended to prevent disease transmission; however, Cryptosporidium was not detected in a sample of pool water. Pool water from the water park met state guidelines for water quality but tested positive for C. parvum. Fecal accidents were reported in both pools. All areas of the water park shared one filtration and treatment system; outbreak prevention recommendations for the water park included installation of ultraviolet (UV) disinfection, as well as education for the staff and the public. (Source: CDC. Cryptosporidiosis outbreaks associated with recreational water use—five states, 2006. MMWR 2007; 56:729–32). August 2006 Colorado Cryptosporidium spp. 12 Certain persons developed cryptosporidiosis after attending a party at a community recreational center with a pool that had UV disinfection in addition to chlorination and rapid sand filtration. Swimming, swallowing water, and getting water in the mouth were significant risk factors. Pool use by diaper-aged children and the use of combined filtration systems for the adult and child pools were suspected to have been contributing factors in the outbreak. (Source: CDC. Cryptosporidiosis outbreaks associated with recreational water use—five states, 2006. MMWR 2007;56:729–32). Chemicals/Toxins June 2005 Michigan Copper sulfate 3 A local resident treated a state lake with copper sulfate to prevent swimmer’s itch by controlling snail populations. The pesticide was applied without a permit; the quantity was 30 times the label-recommended amount for algae treatment and three times the label-recommended amount for snail control. Subsequently, three children who spent time near or in the lake developed respiratory symptoms, and one was hospitalized. A water test conducted within 1–2 months of the pesticide application did not find hazardous levels of copper sulfate in the water.



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO July 2005 Ohio Chlorine gas 19 A chlorine surge at a community pool caused illness in 19 persons. The majority of swimmers were children. The predominant symptoms were breathing difficulties, cough, sore throat, and eye irritation. The recirculation pump failed, but chemical feed pumps continued to feed chlorine and acid. When the mechanical pump was restarted, a concentrated surge of chlorine gas created by the mixing of the concentrated hypochlorous acid and chlorine was introduced into the pool. The facility responded to the event by installing an electrical interlock that would automatically stop the flow of chemicals if the recirculation pump failed. Unidentified April 2005 Minnesota Suspected chloramines 20 A case-control study was conducted after reports of respiratory and ocular symptoms among attendees at a birthday party at a hotel pool. Multiple other symptoms were documented, including burning nose and throat, nausea, and headache; 12 case-patients sought medical care within 1 day of attending the party. Water contact and entering the pool enclosure were significantly associated with illness. The outbreak investigation determined that the chlorine levels in the pool might not have been properly maintained, record-keeping was inadequate, showering facilities in the pool area were inadequate, no pool operator was on duty, and official bather load was exceeded for the pool during the party. July 2005 Florida Suspected jellyfish larvae 24 Attendees of a conference reported symptoms such as fever, fatigue, headache, chills, and muscle ache. Illness was significantly associated with swimming in the ocean and chlorinated resort pools. No clinical specimens were collected because symptoms had resolved before the investigation was initiated. Multiple symptoms were consistent with exposure to toxins released by minute jellyfish larvae (seabather’s eruption). Although weather patterns at the time, as well as the month of the outbreak, supported the hypothesis of seabather’s eruption, investigators concluded that certain illnesses might have occurred as a result of other etiologies. Interview data described poor pool water quality and high bather loads. An inspection of the pool facilities was conducted as part of the investigation and led to pool closure. June 2006 Illinois Suspected low pH 9 Swimmers from two classes at a neighborhood swimming pool had burning rashes on their bodies after they left the pool. The swimmers were ages 4–8 years. The instructor, who was in the water for a total of 80 minutes, reported a similar rash on his arms. Testing indicated that the pool water had a low pH. The exact pH could not be determined; the lower limit for the test strip was seven. The problem was traced back to the automatic sensing unit for feeding acid, which was not working correctly. December 2006 Nebraska Suspected chloramines 24 A child attending a family event at a motel swam for 3 hours in the indoor pool, during which time he developed respiratory symptoms. He was hospitalized overnight with severe chemical epiglottitis and laryngotracheobronchitis. A follow-up investigation identified 24 case-patients who had developed ocular and/or respiratory symptoms after being in or near the pool. The state health department inspected the pool and closed it as a result of multiple state health code violations. Pool water pH was 3.95 (acceptable range: 7.2–7.8); the free chlorine level was 0.8 ppm (acceptable range: 2–10 ppm) and the combined chlorine level was 4.2 ppm (acceptable limit: <0.5 ppm). Pool records indicated that water quality violations had occurred frequently during a 26-day period before the outbreak. Chloramine levels might have been higher on the day that the child became ill because of inadequate ventilation; the only ceiling exhaust fan was turned off, and all of the nearby windows were closed. Although the motel was licensed by the state of Nebraska, it was a nonmunicipal public pool and, therefore, pool operators were not required to undergo training and certification. (Source: CDC. Ocular and respiratory illness associated with an indoor swimming pool—Nebraska, 2006. MMWR 2007;56:929–32).



State in No. of which WBDO cases Date occurred Etiologic agent (deaths) Description of WBDO Vibrio infections August 2005 Louisiana Vibrio vulnificus 1 (1) A man aged 60 years waded for 3 days in flood waters after Hurricane Katrina in New Orleans, Louisiana, and arrived in Texas during the end of August 2005. His medical history included stroke, hypertension, and alcohol abuse. The day after he arrived in Texas, he went to an emergency department; he had ankle wounds and diarrhea. He was released after treatment but was admitted to the hospital 1 day later when Vibrio vulnificus was positively identified from a blood culture. He died in the hospital the next day. (Source: CDC. Vibrio illnesses after Hurricane Katrina—multiple states, August–September 2005. MMWR 2005;54:928–31). August 2005 Mississippi V. parahaemolyticus 1 (1) A man aged 61 years died shortly after seeking medical treatment for V. parahaemolyticus infection; he had hypothermia and multiple second-and third–degree abrasions on his body after exposure to Hurricane Katrina flood waters. The patient was also known to have human immunodeficiency virus infection, coronary artery disease, and hyperlipidemia. (Source: CDC. Vibrio illnesses after Hurricane Katrina—multiple states, August–September 2005. MMWR 2005;54:928–31).

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Date last reviewed: 9/4/2008

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