Veterinary parasitologists warn of high tick risk

Conditions favorable for parasite popultions to thrive; year-round preventives urged.
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May 01, 2013
By dvm360.com staff


Cytauxzoonosis, an often fatal tick-borne disease in cats, is becoming more prevalent, says parasitologist Dr. Dwight Bowman.
Hot or cold? Drought or floods? With the unpredictability of recent weather conditions across the country, it's hard to know what to expect from Mother Nature this summer. But one thing is clear—whatever the weather, it's sure to bring ticks. In fact, they're already here.

Ticks are known carriers of a number of infectious diseases, some of which have been on parasitologists' radar for some time and others that are less well-known but quickly gaining popularity. One of the more common tick-borne diseases that rears its ugly head every year—and shows no sign of relenting—is Lyme disease. And according to initial assessments from the Companion Animal Parasite Council (CAPC), which works with statisticians to evaluate a variety of weather and disease-predicting factors, the threat of Lyme disease for dogs and cats is going to be extremely high this summer.

Dwight Bowman, MS, PhD, professor of parasitology at Cornell University College of Veterinary Medicine, has a similar prediction and says that although veterinarians may see some fluctuations in case load from year to year, Lyme disease continues to spread and is expected to be a problem this year as well. "As long as we have more deer, more rodents and more places for them to live, the number of cases will increase yearly," he says.

And it's not just due a larger reservoir host population. Susan E. Little, DVM, PhD, DEVPC, professor of parasitology at Oklahoma State University Center for Veterinary Health Sciences, states that weather conditions—primarily warmer winters—have created an ideal environment for many tick populations to thrive in and actively seek hosts. "Adults of the deer tick, the one that transmits Lyme disease and anaplamosis to dogs, are out in cooler months," says Little. "Mild winters allow for more days when these ticks can be actively questing and thus put more dogs at risk."

But even harsh weather conditions—last summer's drought, for example—haven't slowed these parasites down. While it was thought that the drought might have put a dent in the lone star tick population, which is responsible for the most common Ehrlichia species infecting dogs in the United States, it's shown a tremendous amount of endurance and is still going strong, according to Little. And the brown dog tick, known to carry Rocky Mountain spotted fever in the U.S. and by nature tolerant to low humidity and high temperatures, took advantage of the drought conditions and continues to thrive.

However, it's not just the most common ticks and the diseases they carry that have parasitologists concerned this year. Emerging protozoan diseases such American canine hepatozoonosis, carried by the Gulf Coast tick, and cytauxzoonosis, carried by both the American dog tick and the lone star tick, are becoming more of a problem and rapidly becoming evident in larger parts of the country, says Bowman.