On the trail
Long before Knowles boarded that Texas-bound plane in 2009, he knew a lot about piroplasmosis. The periodic clusters that
surfaced in temperate-climate states such as Florida proved the parasites sometimes slipped across the U.S. border in horses
that had tested negative for the disease when, in fact, they were positive.
Because the test sometimes gave false negatives, Knowles was charged with developing a more reliable diagnostic test. He also
was instructed to create a standardized treatment to kill the deadly parasites.
Hungry vectors, vulnerable hosts
Armed with two decades of piroplasmosis research and a team of scientists from his USDA unit and WSU, Knowles not only contained
the outbreak but he and colleague Glen Scoles also identified a new blood-sucking culprit that had spread it.
"Prior to that outbreak, we knew of two tick species capable of transmitting the disease. There, we discovered a third," said
He and his team identified the cayenne tick as the predominant carrier, a finding so important that the group later published
a paper about it in the journal Emerging Infectious Diseases.
Eradicating the parasite
All said and done, Knowles and his team did more than identify a new eight-legged transmitter of piroplasmosis and develop
an internationally accepted test to diagnosis it.
With high doses of imidocarb dipropionate, a drug used to treat certain diseases in cattle, they appeared to have eradicated
The outcome of administering the drug was so successful that, after subsequent trials, it is now being evaluated as a standard
treatment protocol in the United States.
"If approved for use, the treatment would offer a way to clear horses of infection," said Hoskins.