Norovirus in Recreational Waters in Arizona

by Jones, Ellen L.

Noroviruses are the leading cause of gastroenteritis in the United States, causing an estimated 23 million illnesses, 50,000 hospitalizations and 300 deaths per year. This virus is transmitted via the fecal-oral route and infections can occur from drinking contaminated water or eating contaminated food, contact with contaminated fomites, inhalation of aerosolized vomitus, or person to person spread. Outbreaks of norovirus following exposure to contaminated recreational water have been documented, as swimmers and others engaged in water recreation often consume recreational water, either purposefully or accidentally, during their activities. In Arizona there have been several outbreaks of norovirus gastroenteritis among people using the recreational waters. In the past four years there have been four consecutive outbreaks of norovirus among rafters on the Colorado River, and in 2003 there was an outbreak of norovirus among a large group of houseboaters on Lake Powell. Norovirus is an emerging pathogen in the state of Arizona. In an effort to better understand its epidemiology, and with the aim of providing recommendations for prevention or minimization of future outbreaks, two investigations were undertaken: an investigation of the outbreak of norovirus among houseboaters on Lake Powell, and a survey of water quality and possible sources of norovirus in the Colorado River. Additionally, historical Colorado River water quality data was reviewed and outbreak epidemiology assessed. To better understand the role of viruses in waterborne 10 recreational disease outbreaks, a review of the literature was conducted and an analysis of 48 recreational waterborne disease outbreaks was done. 11