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WATERBORNE OUTBREAK OF GASTROENTERITIS ASSOCIATED WITH A NOROVIRUS
Citation:
Parshionikar, S., S. WillianTrue, G S. Fout, D. Robbins, S. A. Seys, J. D. Cassady, AND R. Harris. WATERBORNE OUTBREAK OF GASTROENTERITIS ASSOCIATED WITH A NOROVIRUS. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 69(9):5263-5268, (2003).
Impact/Purpose:
Overarching Objectives and Links to Multi-Year Planning
This task directly supports the 2003 Drinking Water Research Program Multi-Year Plan's long term goal 1 for "regulated contaminants" and long term goal 2 for "unregulated contaminants and innovative approaches" under GRPA Goal 2 (Clean and Safe Water). The overarching objective is to provide the Office of Water, Agency risk assessors and managers, academics, the scientific community, state regulators, water industry and industry spokes-groups the methods they need to measure occurrence of waterborne viral pathogens. The methods developed will improve the quality of risk-based assessments and tools used by the Agency to set regulations, policies and priorities for protecting human health and will allow the Agency to assure the public that the appropriate methods are being used to demonstrate that drinking water is safe from pathogenic agents.
Specific Subtask Objectives:
o Evaluate techniques for enhancement of growth of human enteric viruses in support of CCL #2 and #3 and for use in the UCMR (Subtask A; to be completed by 9/05 in support of LTG 2)
o Develop a multiplex RT-PCR method that incorporates internal controls for use in the UCMR (Subtask B; completed 9/03 in support of LTG 2)
o Develop and evaluate new molecular technologies for use in the UCMR. Included will be real-time RT-PCR methods for Norwalk virus and astroviruses, and integrated cell culture/molecular procedures for detection of infectious viruses (Subtask B; to be completed by 9/05 in support of LTG 2)
Description:
The Wyoming Department of Health investigated an outbreak of acute gastroenteritis among persons who dined at a tourist saloon in central Wyoming during October 2001. Human caliciviruses (HuCVs) were suspected as the etiological agent of the outbreak based upon the incubation period, duration of illness and symptoms observed in ill patrons. A retrospective cohort study demonstrated that ill patrons were 4.5 times as likely to have exposure to drinking water and/or ice than non-ill patrons. No food items were associated with illness.
An environmental investigation gave evidence that the saloon's groundwater was contaminated with septage. Water from the saloon's only well was processed for viruses. The processed water sample and stool samples collected from three ill patrons were analyzed by reverse transcription- polymerase chain reaction (RT-PCR) for the presence of HuCV. All positive RT-PCR results were confirmed by sequence and phylogenetic analysis of cloned RT-PCR products. A genogroup I, subtype 3 HuCV stain was found to be present in the well water sample and two stool samples. In addition, a genogroup II, subtype 6 strain was detected in one stool sample. The identification of the same HuCV strain in both the well water and stool samples strongly suggests a link between exposure to well water and the outbreak of gastroenteritis. The presence of genogroup II, subtype 6 strain in one of the stool samples suggests that multiple HuCV strains may have been involved in this outbreak. The laboratory isolation of HuCV strains from outbreak-associated drinking water is relatively novel in the US. This investigation outlines the procedure for virus isolation and illustrates the utility of the RT-PCR for the identification of HuCV in large volumes of water and stool samples obtained during outbreaks of acute nonbacterial gastroenteritis.