Hygiena 2008, 53(3):76-83

Outbreaks Associated with Recreational Water in the United States, 1995-2004

Gunther F. Craun¹, Timothy J. Wade²

¹ Gunther F. Craun & Associates

² U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC, U.S.A.

In this article, we review the causes of 212 recreational waterborne outbreaks and 17,975 cases of illness reported in U.S.A. during 1995-2004. Gastroenteritis was the most frequently (91%) reported illness. Conditions or symptoms related to the skin, ears, or eyes occurred less frequently (6%). Also reported were cases of leptospirosis, acute respiratory illness, meningitis, and primary amebic meningoencephalitis. A bacterial or protozoan etiology was identified in most (71%) outbreaks; 8% of the outbreaks were viral in origin. An etiology was not confirmed for 17% of the outbreaks. Cryptosporidium spp., Pseudomonas aeruginosoa, norovirus, and chemicals were confirmed as the cause of most (69%) outbreaks in treated recreational waters such as swimming and wading pools. Naegleria fowleri, E. coli O157:H7, norovirus, Shigella spp., and avian Schistosomatidae were confirmed as the cause of most (72%) outbreaks in untreated recreational waters such as lakes, ponds, and streams.
Bathers themselves were the most important sources of contamination (e.g, fecal accidents, bathing while ill, large numbers of bathers) for outbreaks in both treated and untreated recreational waters. Sewage discharges, watershed runoff during heavy rainfall, algal blooms, and various animal and avian species were also important sources of contamination for untreated recreational waters. Inadequate operation, maintenance, or water treatment was an important contributing risk factor for outbreaks in treated recreational waters.
Waterborne outbreak surveillance can help identify the etiologic agents, sources of contamination, and treatment/operational deficiencies so that effective prevention and control programs can be implemented. However, the outbreak statistics may not accurately reflect the risks of sporadic or endemic waterborne illness associated with recreational activities in fresh and marine waters. Information from epidemiologic studies that are now being conducted can lead to guidelines to reduce endemic illness risks.

Keywords: waterborne outbreaks, waterborne pathogens, swimming and bathing, water quality, surveillance

Published: September 2008  Show citation