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COORDINATING SYSTEMS-BASED ENVIRONMENTAL PUBLIC HEALTH PRACTICE WITH EPIDEMIOLOGY AND LABORATORY ANALYSIS: A WATERBORNE OUTBREAK OF NORWALK-LIKE VIRUS IN THE BIG HORN MOUNTAINS OF WYOMING
Citation:
Seys, S. A., H. M. Mainzer, A. G. Heryford, A. D. Anderson, S. S. Monroe, G S. Fout, J. P. Sarisky, AND K. J. Musgrave. COORDINATING SYSTEMS-BASED ENVIRONMENTAL PUBLIC HEALTH PRACTICE WITH EPIDEMIOLOGY AND LABORATORY ANALYSIS: A WATERBORNE OUTBREAK OF NORWALK-LIKE VIRUS IN THE BIG HORN MOUNTAINS OF WYOMING. Presented at American Public Health Association Annual Meeting, Philadelphia, PA, November 9-13, 2002.
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:
Background: In February 2001, the Wyoming Department of Health received reports of cases of gastroenteritis among persons who had been snowmobiling in the Big Horn Mountains. Laboratory testing suggested that exposure to a Norwalk-like virus was responsible for the illness.
Methods: Environmental health specialists and epidemiologists from several state and federal agencies coordinated an investigation of environmental risk factors and system-based failures. The environmental assessment of three area lodges included food service operations, water supply systems, and sewage disposal. A retrospective cohort study was conducted among 82 guests to identify risk factors associated with illness. Stool and water samples were collected for laboratory analysis.
Results : Statistical analysis suggested that illness was associated with water consumed at one of the three area lodges (RR=3.3, 95% C.I.=(1.4,7.7)). Reverse transcriptase-polymerase chain reaction (RT-PCR) testing on 13 stool samples yielded 8 positives for Norwalk-like virus (NLV) genogroup II, with 3 distinct sequence types detected. Fecal contaminaiton of one of three operating wells was also found and one of the samples tested positive for NLV genogroup II. The environmental assessment of the property revealed that an inadequately installed sewage system was delivering effluent into shallow soil with poor filtering capacity.
Conclusion: This outbreak illustrates waterborne transmission of viral gastroenteritis and the advantages of coordinating a systems-based model of enviromental asssessment with traditional epidemiologic and laboratory practices. Preventing future system deficiencies depends on understanding the relevant protective components of facility operations including the surrounding physical environment, food service, water supply, and sewage systems.