Posted: Saturday, February 10, 2007 12:00 am
JACKSON (AP) - Biologists recently detected fewer cases of brucellosis exposure in elk in the Buffalo Valley north of here than they did a year ago.
But they say there are too many research uncertainties to draw clear conclusions from either this year or last year's results.
Researchers captured 41 adult female elk and fitted them with radio-collars. They also implanted transmitters to monitor where calving occurs or where calves are aborted.
The researchers got 39 suitable blood samples to test for exposure to brucellosis, a bacterial disease that can cause elk to abort their calves and can spread to cattle.
Of those 39 samples, two came back positive for brucellosis exposure. That was a rate of 5 percent, down from 20 percent a year ago.
"This is why we don't make broad assumptions on a single year's data," said Terry Kreeger, a wildlife veterinarian for the Wyoming Game and Fish Department. "Last year, some of the public made sweeping conclusions based on one year's data, which was obviously speculative."
He said it was unknown "and perhaps unknowable" why last year's rate was 20 percent, which was much higher than usual.
"It was highly unlikely that it was due to any management action, such as feeding, because this year's prevalence reverted to historic levels," he said. "Successive years of data must be collected and studies repeated before accurate conclusions can be made."
Hank Edwards, a state wildlife disease specialist, said this year's results also must be interpreted cautiously.
"All we know from this is that it is a snapshot in time at this single location," he said. "There are many variables to this data which we don't understand."
For example, he said, it's unclear whether serology - the study of immune responses that indicate exposure to disease - accurately reflects brucellosis infection rates.