Lone star liabilities: No Lyme, but lots to be leery of

A female lone star tick. (Image: Michael L. Levin, PhD; CDC Public Health Image Library)The lone star tick may not transmit Borrelia burgdorferi, the Lyme disease bug, but there's still plenty to be concerned about when it comes to Amblyomma americanum-whether you're a two-legged or four-legged individual. During the AVMA's annual convention in Indianapolis this week, a veterinary parasitologist, human-medicine allergist and PhD entomologist all discussed the lone star tick in a session sponsored by Boehringer Ingelheim.

Risks to pets. Brian Herrin, DVM, PhD, DACVIM (parasitology), a postdoctoral researcher at Oklahoma State University Center for Veterinary Health Sciences, discussed the pathogens that the lone star tick does transmit, and they're nothing to blow off. Ehrlichia and Rickettsia bacterial species are two major concerns in dogs, and diagnosis can be tricky. With Ehrlichia species, a positive in-clinic test result may not indicate imminent clinical disease (which means the dog may or may not need doxycycline), and with Rickettsia, clinical signs may manifest before antibodies appear (making it a “treat, then confirm” disease, Dr. Herrin says).

In cats, Cytzauxzoon felis infection is often fatal despite treatment, and owners should be encouraged to check their cats for ticks, since it takes 36 hours for A. americanum to transmit the pathogen, Dr. Herrin says. The best strategy is to know the risks in your area-with awareness that the lone star tick is marching steadily northward-and create specific diagnostic and treatment protocols accordingly.

Risks to people. Scott Commins, MD, PhD, an allergist at the University of North Carolina-Chapel Hill, has researched the connection in people between bites from larval lone star ticks (often called “seed ticks”) and the development of allergy to mammalian meat-beef, pork, lamb, bison and so on. In a case of medical detective work, he and a team of researchers identified cases in which people who had tolerated meat their whole lives started experiencing itching, swelling and hives six to eight hours after eating it.

In comparing incidence of the allergy (the culprit was identified as alpha-gal, a type of sugar found in lower mammals but not in humans) to the territory of the lone star tick, the team eventually determined that tick bites were triggering the allergy in people. The research is ongoing, including whether there's any similar process that takes place in dogs.

Random facts. Finally, Thomas Mather, PhD, professor of entomology and director of the TickEncounter Resource Center at the University of Rhode Island, offered some interesting facts about lone star ticks and a quick lesson in tick identification. One “bet you didn't know” item: The lone star tick is super-speedy, meaning it can scoot up your leg and under your shirt-or into your dog or cat's fur-faster than the deer tick or the American dog tick. Also, tick species are often misidentified, Dr. Mather says, but focusing on the tick's scutum (or “shield” beneath the head) and the differences among them will help with a proper ID. Dr. Mather's team runs the tickencounter.org website, which offers more resources.

No matter what species the tick and what disease process it triggers, ticks are bad news. After all, “every year is a bad year for ticks-it only takes one,” as Dr. Herrin puts it. Smart use of tick-prevention products, plus strategies such as yard cleanup and frequent tick checks-will help keep people and pets safe and disease at bay.