On May 3, 1983, the Salt Lake City-County Health Department notified the Office of Epidemiology and Surveillance, Utah Department of Health, of complaints from individuals who had developed rash illnesses or earaches after swimming at a local waterslide* on April 30, 1983. By May 7, 265 cases were identified among 650 persons who visited the waterslide on April 30 (Figure 1).

A case was defined as a person who developed rash or earache after swimming at the waterslide between April 23 and May 7, 1983 (1). Approximately 91% of patients had rashes, while the remainder reported earaches and no rashes; half of those 9% were diagnosed as having otitis externa. Other symptoms included headache (42%), fatigue (30%), muscle aches (34%), red or burning eyes (31%), and fever (26%). The incubation period ranged from 8 hours to 5.5 days (mean 48 hours).

Samples taken from papulovesicular lesions of seven individuals were submitted to various laboratories for culture and antibiotic sensitivity testing; four of these were positive for P. aeruginosa. Drainage from the ears of two exposed children also grew P. aeruginosa, as did multiple environmental samples from the water and pool surroundings. Antibiotic sensitivity patterns of clinical and environmental samples were identical. Isolates were identified as P. aeruginosa serogroup 0:4.

Although cases generally resolved spontaneously without serious complications, persistent purulent otitis externa was seen. One patient was hospitalized with a temperature of 40 C (104 F), severe dermatitis, and axillary lymphadenopathy, but blood cultures were negative. His illness resolved rapidly following intravenous gentamycin.

Two church groups, consisting of 218 members, that had visited the waterslide on April 30 completed questionnaires concerning clinical and exposure histories. Of 152 persons exposed to the waterslide, 116 (76%) were ill, while none of 66 unexposed persons were ill (p 0.0001). Showering within 30 minutes after last exposure did not reduce the risk of developing a rash (26% vs. 23%). The mean age of patients was 14.5 years; that of exposed well persons was 17.5 years, suggesting younger children were more likely to become ill (possibly because they tended to spend more time in the water).

An inflatable, plastic bubble covered the entire pool and deck areas and produced water and ambient air temperatures of 35 C (95 F) and a relative humidity of 95%. The water was treated by a hypochlorite feeder containing chlorine stabilized with cyanuric acid. The waterslide has a circulation system that uses two pumps and four diatomaceous earth filters. One pump had failed several days before April 30, and the second pump failed early that morning. The pool remained open while repairs were under way, although many individuals reported the water was turbid and foamy that day. On May 1, the pool was closed by the operator to allow for testing of the pumps and for hyperchlorination.

The pool was subsequently reopened for 3 weekday afternoons; intensive surveillance found no cases resulting from exposures on those days alone or from exposure before April 30. The waterslide was closed on May 5 and was drained, cleaned, and retested for compliance with free-chlorine and pH standards (2). After reopening for 2 days, pool water and environmental samples indicated a continuing problem with achieving adequate disinfection, and the slide was again closed. Since that time, the plastic bubble and poolside indoor-outdoor carpeting have been removed, and a continuous gas chlorinator has replaced the hypochlorite feeder. Daily environmental samples have been satisfactory, and the waterslide has now been reopened. Continuing physician-based surveillance has not identified any new or recurrent cases. Reported by DM Perrotta, PhD, RE Johns, Jr, MD, State Epidemiologist, Utah Dept of Health; R Bradley, MD, Salt Lake City, J Jacobson, MD, University of Utah Medical Center, K Miner, T Sadler, HL Gibbons, MD, Salt Lake City-County Health Dept; Special Pathogens Br, Div of Bacterial Diseases, Hospital Infections Program, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: This is the largest reported outbreak of P. folliculitis and the first outbreak associated with a waterslide. P. aeruginosa serotype 0:4 has not previously been reported to be linked with P. folliculitis (3). Most of the reported outbreaks associated with hot tubs or whirlpools have shown P. aeruginosa serotypes 0:9 or 0:11 to be the responsible pathogen. In this outbreak, the source of contamination could not be determined, but small numbers of pseudomonads are commonly found in and around swimming pools (4). Warm and humid conditions, combined with ineffective chlorination, probably led to overgrowth of P. aeruginosa in the pool and deck area.

The frequency of systemic complaints (headache, fever, nausea, muscle ache) in this outbreak was higher than in other Pseudomonas folliculitis outbreaks. Whether serotype 0:4 is more pathogenic than other P. aeruginosa serotypes or whether other personal or environmental risk factors contributed to the development of these complaints is unknown. Although water samples were not examined for other etiologic agents--such as Legionella pneumophila, the cause of Pontiac fever--serologic studies are currently under way in an attempt to explain the high rate of systemic complaints.

References

1. Gustafson TL, Band JD, Hutcheson RH, Jr, Schaffner W. Pseudomonas folliculitis: an outbreak and review. Rev Infect Dis 1983;5:1-8.

2. Center for Environmental Health. Swimming pools--safety and disease control through proper design and operation. Atlanta, Georgia: Centers for Disease Control, Department of Health and Human Services, March 1983.

3. CDC. Otitis due to Pseudomonas aeruginosa serotype 0:10 associated with a mobile redwood hot tub system--North Carolina. MMWR 1982;31:541-2.

4. Zacherle BJ, Silver DS. Hot tub folliculitis: a clinical syndrome. West J Med 1982;137:191-4.

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