Epidemiology and Infection

Short Report


Cryptosporidiosis from a community swimming pool: outbreak investigation and follow-up study

T. K. BOEHMERa1a2 c1, N. B. ALDENa2, T. S. GHOSHa2 and R. L. VOGTa2

a1 Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA, USA

a2 Tri-County Health Department, Greenwood Village, CO, USA


Tri-County Health Department investigated an outbreak of cryptosporidiosis linked to a community swimming pool. A cohort study was conducted in 37 persons who were invited to the pool party; 12 (57%) of 21 attendees had primary cryptosporidiosis infection. Risk factors for illness included swimming, getting water in mouth, and swallowing water. The pool met chlorination guidelines and used UV light irradiation, a supplemental disinfection technology that inactivates Cryptosporidium. A follow-up survey of the cohort was completed 7–8 weeks after the pool party; four (25%) of 16 non-attendees had secondary cryptosporidiosis infection. The median duration of illness, including patients with recurring symptoms, was 26 days. Clinical response rate to nitazoxanide, a therapeutic agent, was 67%. This study is unique because it describes a cryptosporidiosis outbreak from a well-maintained community swimming pool using supplemental disinfection. It also reports information on disease burden and treatment response.

(Accepted April 08 2009)

(Online publication May 11 2009)


c1 Author for correspondence: Dr T. K. Boehmer, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, MS F-58, Atlanta, GA 30341, USA. (Email: tboehmer@cdc.gov)