Citation:

CASHDOLLAR, J., G. FOUT, D. R. DAHLING, AND S. PARSHIONIKAR. A COLLABORATIVE EFFORT TO IDENTIFY THE CAUSATIVE AGENT OF TWO WATERBORNE OUTBREAKS OF GASTROENTERITIS IN WYOMING. Presented at 2005 EPA Science Forum, Washington, DC, May 16 - 18, 2005.

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:

Two outbreaks of acute gastroenteritis were reported to the Wyoming Department of Health in 2001. The first was reported in February from recent vacationers of a snowmobile lodge. The second was in October among diners of a tourist saloon. The duration and type of symptoms exhibited by the individuals affected during the outbreaks suggested that noroviruses could be the causative agent. A collaborative investigation by individuals from key federal and state agencies, as well as academic institutions, was conducted in order to determine the causative agent or agents responsible for each outbreak. Both projects had a three-pronged approach: (1) an epidemiological investigation that was performed to identify any common routes of exposure among those afflicted with gastroenteritis, (2) an environmental survey that was done on the site of each outbreak in order to determine possible sources of contamination, and (3) a laboratory analysis that was performed on well water and fecal samples.

With each outbreak, epidemiological studies revealed a close association between water consumption and illness. In addition, environmental surveys in both outbreaks determined that the water supply was vulnerable to fecal contamination. Furthermore, water samples were tested for coliform bacteria using standard methods and for enteric viruses using molecular assays based on reverse transcription polymerase chain reaction (RT-PCR) and DNA sequencing techniques. In addition, stool samples were analyzed for the presence of noroviruses. Well water samples in both cases were positive for coliforms, which are indicators of fecal pollution, while molecular assays confirmed the presence of noroviruses. In each outbreak, a single norovirus strain was identified in the well water and fecal samples, thereby linking the water contamination with the gastroenteritis.

The partnerships that were formed to complete these investigations allowed for a timely and thorough study. Additionally, the work performed by the project partners created an atmosphere that will allow for future collaborative efforts. These investigations demonstrate that the U.S. Environmental Protection Agency's viral concentration and molecular methods, in conjunction with epidemiological and environmental analyses, are very useful in outbreak studies. The methods used in this study can be performed in most laboratories with trained personnel and appropriate equipment, and their use would allow for routine monitoring of enteric viruses in drinking water.

Record Details: