AdvisorGerba, Charles P.
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PublisherThe University of Arizona.
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AbstractThe human health significance of waterborne viruses has previously relied on epidemiological data from documented waterborne outbreaks. It is difficult, however, to assess the risks involved to individuals and communities from exposure to low levels of contamination. Risk assessment is a useful tool in the interpretation of water quality data and can be used to better understand the significance of exposure to low-level contamination of viruses in water. Microbial risk assessment was applied to determine the risks associated with environmental exposure to waterborne coxsackievirus and adenovirus. Annual risks of infection for drinking water were determined to be as high as 10⁻¹ for both coxsackievirus and adenovirus at exposure levels of 0.13 PFU/l and 0.001 IU/l, respectively. A comprehensive cost-of-illness analysis was conducted for three waterborne viruses--Norwalk virus, rotavirus, and non-polio enterovirus--to determine the economic impact of waterborne viruses in the United States. Annual medical costs and productivity losses were estimated in 1993 dollars using actual outbreak information and data from epidemiological studies. It was estimated that $1.1 to $6.9 billion is spent each year in the United States due to these viral illnesses, with potentially $0.39 to $2.4 billion attributable to water. The United States Environmental Protection Agency (USEPA) has initiated the Information Collection Rule (ICR) in which water utilities serving >100,000 people will be required to collect data on the concentrations of specific microorganisms in source and finished water beginning in 1997. Selected water utilities will be required to archive water samples for possible further viral analyses. A risk assessment approach was undertaken to determine which virus would be appropriate for the analyses of the archived water samples. The following viruses were selected based on the nature of the different diseases associated with each, their occurrence in waterborne outbreaks, and their resistance to inactivation by disinfectants: rotavirus, coxsackievirus, hepatitis A virus, adenovirus, Norwalk and Norwalk-like viruses, astrovirus, and hepatitis E virus. The polymerase chain reaction (PCR) is the recommended detection method. The results of these analyses will provide both a database on the occurrence of these viruses in water as well as their susceptibility to water treatment.
Degree ProgramGraduate College
Soil, Water and Environmental Science