HELENA, Mont., Jan. 15 (UPI) -- Canine parvovirus is suspected in a precipitous drop in the population of wolves at Yellowstone National Park.
Park biologists say they will let nature take its course, the New York Times reported.
"Parvo can be vaccinated for and can be treated, but we wouldn't do it because we couldn't catch every animal," wolf biologist Daniel Stahler told the Times. "And this allows them to build up a natural resistance."
The census found 22 pups, compared with 69 last year. The total count of wolves dropped to 118 from 171, the lowest since 2000.
Scientists will take blood samples from surviving pups in the next several weeks to test for the presence of antibodies, to confirm exposure to canine parvovirus, which causes severe diarrhea and dehydration.
Canine parvovirus was discovered in the United States in 1978. Extremely hardy, the disease spread rapidly to domestic dogs and then into wild animal populations.
Biologists suspect it was introduced to Yellowstone by a tourist's infected dog or a coyote. The virus persists in the soil for months and a wolf could catch it from simply sniffing contaminated soil, the biologists said.
