Project Number:
DNR-165
Other Project Number:
WR01R021
Funding Year:
2001
Contract Period:
3/1/2001 - 6/30/2002
Funding Source:
DNR
Investigator(s):
PIs:- Randy Hunt, USGS
- Mark Borchardt, Marshfield Clinic
Abstract:
Human gastrointestinal viruses are known to contaminate municipal drinking water wells. In one peer-reviewed study, 141 of 448 groundwater sites (31.5%) in 35 states were positive for viruses. It is further known that approximately half of all waterborne infectious disease outbreaks are due to the consumption of contaminated groundwater. However, few studies have examined the routes by which pathogenic viruses enter drinking water wells. One potential route of virus entry into wells is surface water infiltration. Large surface water bodies, like the Mississippi River, are significant sources
for fecal-related pathogens; these pathogens can move with infiltrating surface water and potentially enter adjacent drinking water wells. Ideally, these vulnerable wells could be identified and additional water treatment steps taken as necessary.
OBJECTIVES
The primary objective of the present study was to monitor the municipal drinking water wells of La Crosse, Wisconsin, for human gastrointestinal viruses and relate the amount of Mississippi River water infiltrating the wells to the frequency of virus detection. A secondary objective was to relate
microbial indicators of water sanitary quality with the occurrence of gastrointestinal viruses.
METHODS
One river water site and four drinking water wells in La Crosse, WI were sampled monthly from March 2001 to February 2002. All samples were taken prior to chlorination at the wellhead. The wells selected for study were predicted to have different levels of surface water contributions based on previous hydrogeological modeling. The actual amount of surface water entering the wells was measured during the study based on 18O/16O and 2H/1H ratios. Water samples were analyzed by reversetranscription polymerase chain reaction (RT-PCR) for five groups of viruses: enteroviruses, rotavirus, hepatitis A virus (HAV) and norovirus genogroups 1 and 2. This method detects the presence of viral RNA. Enteroviruses detected by RT-PCR were further analyzed by nucleotide sequencing to identify the type of enterovirus. In addition, samples were analyzed by cell culture for the presence of infectious enteroviruses and HAV. Tests for microbial indicators of sanitary quality included total coliforms, E. coli, fecal enterococci, and somatic and male-specific coliphages.