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Clark strives to learn what makes Lyme disease tick

Dr. Kerry Clark outside studying mosquitoes

Creepy, crawly and incredibly pervasive throughout Florida’s woodlands, ticks are viewed by many as an unavoidable nuisance for outdoors aficionados.


They’re much more than simple annoyances to one University of North Florida professor, who views these small arachnids with a potent mixture of concern and reverence. On one hand, they’re a considerable danger to public health. On the other, they could help unlock valuable secrets about the spread of Lyme disease across the country.


Dr. Kerry Clark and his colleagues have identified two different species of bacteria previously unknown to infect humans with Lyme disease. The tick species that carries these types of bacteria was previously believed to be incapable of transmitting Lyme disease.


“My research has had one goal in mind, to find out what’s really going on with Lyme disease,” Clark said. “That goal has been fairly controversial because there are so many problems and bits of misinformation plaguing the diagnosis of Lyme disease. Common knowledge says there isn't supposed be much Lyme disease down here [Georgia and Florida], but we’re proving that to not be true.”


The International Journal of Medical Sciences published Clark’s research in May. In it, Clark identifies two additional Lyme disease species, Borrelia americana and Borrelia andersonii, that were found in patients living in the southeastern United States. The common lone star tick, which was previously believed to be incapable of transmitting Lyme disease, was implicated as the carrier in some of these cases.


His research takes the existing Lyme disease testing methods to task, suggesting that current antibody tests for the disease need to detect far more than just one bacterial species. This limited focus by the medical community has caused many patients with Lyme disease symptoms — fatigue, joint pain, central nervous system issues — to be falsely diagnosed with other ailments, such as multiple sclerosis or amyotrophic lateral sclerosis. Clark’s new findings that the lone star tick is also a carrier significantly expand the geographic danger zone for Lyme disease.


“If only one percent of these ticks are able to transmit Lyme disease, it poses a tremendous threat to public health because lone star ticks are known to bite humans so frequently,” said Liz Schmitz, president of the Georgia Lyme Disease Association.


After heading into the field and acquiring multiple test subjects, Clark and his team identified lone star ticks removed from humans who tested positive for Lyme bacteria, including the species of Borrelia burgdorferi, already known to cause the disease in North America. Some of the ticks removed from the patients tested positive, too. Lone star ticks are the most commonly found species biting humans in the Southeastern U.S.


Patrick Valois, a UNF student research assistant who worked with Clark, said he found the work particularly rewarding, given that his findings could have a positive public health impact across the country.


“There are all these misdiagnoses happening, and this research debunks all sorts of conventional wisdom,” Valois said. “Being able to work on something as important as this as a student is amazing.”


The next stage of Clark’s research involves analyzing hundreds of cases of Lyme disease, many of which involved patients from the South. The working hypothesis is that different species of bacteria will be present in most of the subjects, and the carrier tick won’t be limited to the oft-cited black-legged deer tick.


“I’m not going to stop until the process for diagnosing Lyme disease is updated,” Clark said. “This could be seen as a public health epidemic, and people need to know.”