Outbreak of cryptosporidiosis at a California waterpark: employee and patron roles and the long road towards prevention

Abstract

In August-September 2004, a cryptosporidiosis outbreak affected >250 persons who visited a California waterpark. Employees and patrons of the waterpark were affected, and three employees and 16 patrons admitted to going into recreational water while ill with diarrhoea. The median illness onset date for waterpark employees was 8 days earlier than that for patrons. A case-control study determined that getting water in one's mouth on the waterpark's waterslides was associated with illness (adjusted odds ratio 7.4, 95% confidence interval 1.7-32.2). Laboratory studies identified Cryptosporidium oocysts in sand and backwash from the waterslides' filter, and environmental investigations uncovered inadequate water-quality record keeping and a design flaw in one of the filtration systems. Occurring more than a decade after the first reported outbreaks of cryptosporidiosis in swimming pools, this outbreak demonstrates that messages about healthy swimming practices have not been adopted by pool operators and the public.

Distribution of Cryptosporidium parvum subtypes in calves in eastern United States

“…In addition to the studies of transmission of C. parvum in calves, GP60 subtyping was also used in tracking the source of contamination in waterborne and foodborne outbreaks of cryptosporidiosis (Glaberman et al 2002;Xiao et al 2003;Chalmers et al 2005;Blackburn et al 2006;Wheeler et al 2006). Even though in several occasions a direct linkage at the subtype level between outbreak cases and the implicated food or water has been made (Glaberman et al 2002;Blackburn et al 2006), the power of the approach was compromised by the lack of baseline data on the distribution of C. parvum subtypes in the same geographic area.…”

Cryptosporidium outbreaks associated with swimming pools

“…In one outbreak investigation, there was a statistically significant association between getting sick and having water in the mouth or standing under a sprinkler (OR 5.1, 95%, CI 2.1Á12.5) (Mathieu et al 2004). Similarly in a study from California, Cryptosporidium illness was associated with having water splashed on the face or having the head dunk into the water while on the waterslide (OR 24.0, 95% CI 3.1Á187.9) (Wheeler et al 2007). In a study from Manitoba, persons who immersed their heads into the water were more likely to become ill than those who did not (OR 6.5, 95% CI 2.6Á24.9) …”

“…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).…”

“…In an outbreak in California, the life guards on duty were sick and no measures were taken to prevent them from working (Wheeler et al 2007). The sick life guards were in the water while they were symptomatic and likely contaminated the water.…”

“…The sick life guards were in the water while they were symptomatic and likely contaminated the water. The lack of education and a clear policy to keep lifeguards and employees out of the water while sick led to this incident (Wheeler et al 2007). …”