An outbreak ofCryptosporidium hominisinfection at an Illinois recreational waterpark

Abstract

Cryptosporidium has become increasingly recognized as a pathogen responsible for outbreaks of diarrhoeal illness in both immunocompetent and immunocompromised persons. In August 2001, an Illinois hospital reported a cryptosporidiosis cluster potentially linked to a local waterpark. There were 358 case-patients identified. We conducted community-based and waterpark-based case-control studies to examine potential sources of the outbreak. We collected stool specimens from ill persons and pool water samples for microscopy and molecular analysis. Laboratory-confirmed case-patients (n=77) were more likely to have attended the waterpark [odds ratio (OR) 16.0, 95% confidence interval (CI) 3.8-66.8], had pool water in the mouth (OR 6.0, 95% CI 1.3-26.8), and swallowed pool water (OR 4.5, 95% CI 1.5-13.3) than age-matched controls. Cryptosporidium was found in stool specimens and pool water samples. The chlorine resistance of oocysts, frequent swimming exposures, high bather densities, heavy usage by diaper-aged children, and increased recognition and reporting of outbreaks are likely to have contributed to the increasing trend in number of swimming pool-associated outbreaks of cryptosporidiosis. Recommendations for disease prevention include alteration of pool design to separate toddler pool filtration systems from other pools. Implementation of education programmes could reduce the risk of faecal contamination and disease transmission.

Cryptosporidium outbreaks associated with swimming pools

“…In Canada and the United States, the two most common species of Cryptosporidium associated with outbreaks in swimming pools are Cryptosporidium parvum and Cryptosporidium hominis (Hopkins et al 2013;Mathieu et al 2004;Health Canada 2004;Polgreen et al 2012;Boehmer et al 2009;Wheeler et al 2007;Causer et al 2006). Many studies report that pool-fouling was a risk factor for infection with Cryptosporidium (Hopkins et al 2013;Mathieu et al 2004;Health Canada 2004).…”

“…Another contributing factor to the spread of pathogens is the interconnected design of pools and shared filtration systems, leading to the cross contamination of pools (Causer et al 2006). The water park described by Causer et al (2006) had a toddler pool, lap pool, and a ''lazy river'' .…”

“…The water park described by Causer et al (2006) had a toddler pool, lap pool, and a ''lazy river'' . The filtration systems for the toddler pool and lap pool were interconnected (Causer et al 2006).…”

“…The water park described by Causer et al (2006) had a toddler pool, lap pool, and a ''lazy river'' . The filtration systems for the toddler pool and lap pool were interconnected (Causer et al 2006). Although the reported diarrheal incidents happened only in the toddler pool, Cryptosporidium oocytes were detected in both the lap pool and the toddler pool water samples.…”

Biofilms Reduce Solar Disinfection of Cryptosporidium parvum Oocysts

“…ryptosporidium parvum is a public health concern, infecting thousands of individuals as a result of contaminated water (2,3,13,32). Traditional water treatment targeting Cryptosporidium is difficult (28).…”