A little off-road recreation may result in more rats carrying the hantavirus, according to University of Utah researchers.
The scientists found 30 percent of the deer mice near the Bureau of Land Management's Little Sahara Recreation Area are infected with hantavirus. Little Sahara is located 40 miles southwest of Provo.
The researchers hypothesize that the high infection rate, which is three times that of similar habitats in the Great Basin area, is a result of heavy off-road vehicle use in the area.
"One thing that is pretty striking about this study area is that it has a lot of traffic," said assistant biology professor Denise Dearing, who led the research team.
She suggests the abundance of dirt roads in the recreation area create "habitat islands" that force deer mice and wood rats into smaller pockets of vegetation.
In tight quarters, the mice fight more readily, passing the disease through saliva and blood.
Dearing says the ORV hypothesis still needs further research. She has a grant proposal prepared for the National Institutes of Health to continue the study.
Researchers have not determined if the increased prevalence of hantavirus will result in more humans contracting the disease, but Dearing believes it is probable.
"You've got more deer mice with hantavirus, so humans have an increased risk of contact with infected deer mice," she said.
The infection level found in the recreation area mirrors that of the Four Corners area in 1993, the location of the first widely reported hantavirus outbreak.
"The high prevalence was thought to be a factor leading to the outbreak," she said.
From the first recorded case eight years ago to Dec. 7, 2000, the United States has reported 277 hantavirus cases, more than 100 resulting in death. Utah reported 14 cases during the period.
Dearing, who said she is sympathetic to environmental groups, said the research was not intended as an attack against ORVs.
"There should be a balance between ORV use and protected land. When habitats get seriously degraded, they should be given a rest and a chance to recover," she said.
Dearing said further research is needed to determine whether the recreation area has been seriously degraded.
Dearing, biology student Rachel Mackelprang and Stephen St. Jeor, a virologist at the University of Nevada-Reno, were trying to quantify the prevalence of hantavirus in wood rats when the issue of ORV use in the area surfaced as a corollary issue.
Dearing discovered three years ago during a separate study in the recreation area that wood rats also carry the disease. She set three traps at 40 separate wood middens, baited with the wood rats' favorite nesting materials — cotton, oats and peanut butter.
She caught not only wood rats but deer mice, pinyon mice, kangaroo rats, pocket mice and sagebrush voles. While some wood rats had the virus, the prevalence in deer mice far surpassed that of the other rodents.
During trips to the recreation area, students had questioned how ORV use in the area might be affecting the mice.
Dearing didn't take the inquiries too seriously until one student brought in an aerial photo of the study site that showed the land spattered with dirt roads.
"You can't imagine how many roads are out there," Dearing said.
She compared the tentative hypothesis against previous research. She found studies indicating that mowed fields or roads force mice into concentrated areas where they are more susceptible to infections. She also found a previous study conducted by the Centers for Disease Control and Prevention that found only 11 percent of deer mice had hantavirus in four other Great Basin sites with similar habitat but without the concentrated ORV use.
Dearing released information about the research at a Saturday press conference at the U. The new study will appear in the May-June issue of the journal Emerging Infectious Diseases, published by the CDC.
E-mail: mcanham@desnews.com