Jul. 18 2017

Keeping Us Safe from Tick-Borne Illness

As the tick population grows, Rafal Tokarz is developing new ways to identify the pathogens that cause disease

Summer is the season for outdoor fun—and tick bites. By some reports, the risk for tick-borne disease may be worse this year, thanks in part to a mild winter.

In fact, ticks have been ascendant for years, according to Rafal Tokarz, an associate research scientist at the Center for Infection and Immunity at the Mailman School who develops methods to identify the pathogens behind the illnesses ticks carry.

“The range of ticks has increased substantially in the past decade or two,” says Tokarz, “especially the ticks that transmit Lyme.” Once confined to the Northwest, these ticks are now seen lurking in vegetation in half of counties in the United States—a move that could be hastened by climate change.

Today there are three times as many reported Lyme cases as there were 20 years ago. While greater public awareness may be driving some of this increase in diagnoses, reported cases are still believed to be only the tip of the iceberg. Lately, however, new technologies—including those Tokarz has developed—are shedding light on Lyme and other tick-borne threats.

In a paper published this spring in the journal mSphere, Tokarz introduced a method to simultaneously test for Lyme and four other common pathogens transmitted by deer ticks, including the rare but potentially fatal Powassan virus.

Initially tested on ticks collected from the woods on Long Island and in Connecticut, Tokarz’s method revealed that about half of the ticks carried Borrelia burgdorferi, the bacteria behind Lyme disease. Of these, one-quarter also carried Babesia microti, microscopic parasites that cause babesiosis, a serious illness. Overall, 45 percent of adult ticks Tokarz tested carried more than one pathogen.

These insights might explain why as many as one in five people treated for Lyme disease continue to feel symptoms months or years later. According to Tokarz, individuals with Post-Treatment Lyme Disease Syndrome might also be infected with one or more additional tick-borne diseases. “Gathering data on co-infections is particularly important in light of the fact that antibiotics used for Lyme disease may be ineffective for other tick borne infections,” he says.

An ongoing Tokarz-led project is aimed at identifing other tick-borne threats. In a study of three human-biting ticks in New York State, he discovered 30 novel tick-associated viruses. The project, funded by the Steven & Alexandra Cohen Foundation, is also looking at whether these viruses spread to humans and lead to disease. The identification of novel pathogens is an important first step that can eventually lead to the development of diagnostic tests.

Meanwhile, Tokarz is putting the finishing touches on a testing method that could revolutionize diagnosis of known tick-borne illnesses. Currently, when your doctor suspects you have a tick-borne illness, you can only be tested one pathogen at a time, making them time-consuming and costly. By contrast, the new approach, details of which will be reported in a forthcoming journal article, can simultaneously identify infections with a broad-range of tick borne agents —and with more accurate results. 

Of course, the best outcomes come from avoiding tick bites altogether.

Any time Tokarz is in the woods, he takes care to protect himself by covering his skin with a long sleeve shirt and socks pulled up over loose-fitting pants. He thoroughly checks himself for ticks, which this time of year are often no bigger than a poppy seed. And they’re not always in the obvious places. He once found one on the sole of his foot. “You can never be too careful,” he says.