This month, an unusual form of cargo will begin winding its way through the postal system in Missouri: live ticks.
As part of a two-year statewide effort to track the tiny parasites, scientists from A.T. Still University in Kirksville and the Missouri Department of Conservation are asking residents to send in any ticks they find. The team plans to map the distribution of tick species on a county-by-county basis, along with their bacterial pathogens.
Missouri offers a Goldilocks-like environment for ticks, said Deborah Hudman, who has spent years studying tick populations in the U.S.
“It’s not too hot, not too cold, lots of humidity; it’s just right,” said Hudman, a researcher in microbiology and immunology at A.T. Still University, 90 miles north of Columbia. “We also have lots of wildlife, lots of hosts and lots of habitat. That’s why our tick populations are just absurd.”
There are four tick species that bite humans in Missouri: the lone star tick, the black-legged tick, the American dog tick and the Gulf Coast tick.
Despite how abundant the parasites are in Missouri’s forests and farmland, scientists have limited data on where each species lives. Collecting and identifying the parasites in every county is time-consuming, meaning there are large swaths of the state that lack even the most basic information on tick populations.
Three-quarters of Missouri counties, for instance, have no data on whether the black-legged tick, a vector of Lyme disease and other human pathogens, is present. Even the most common species statewide, the lone star tick, remains understudied, with nearly 40% of counties reporting no information on the species.
That doesn’t necessarily mean the ticks aren’t there, Hudman said, but rather that no one has ever looked.
In recent decades, some species have begun emerging earlier in the spring, while others have colonized new areas, likely related to climate change. The Gulf Coast tick, once confined to coastal regions of the southeastern U.S., has expanded north into Missouri and Illinois.
To track where tick species are statewide, Hudman and the Missouri Department of Conservation are enlisting the public’s help — by asking them to mail in live ticks.
Missouri residents should place each live tick in a separate plastic zipper bag, along with a damp paper towel or cotton ball and a submission form, detailing when and where the tick was collected.
By relying on citizen scientists, Hudman and her colleagues are aiming for an once-unattainable goal: to catalog the state’s tick populations, without visiting each of its 114 counties. “I can focus on one county and do a somewhat good job, but if I have the citizens of Missouri sending me samples, this can get accomplished,” she said. “This is the only way it can get accomplished.”
Once they identify the tick samples, the team plans to slice them in half with a small scalpel and test them for four common tick-borne bacterial pathogens known to cause illness in humans: borrelia, ehrlichia, rickettsia and francisella.
A project of this scale, surveying both tick distribution and the bacteria carried, has never been attempted in Missouri, said Matt Combes, an MDC researcher. The data will likely prove useful for patients and health care workers in the future, he said.
“In order for doctors to make better diagnoses of tick-borne illnesses, it'd be very helpful for them to have a map of where the ticks occur and where the pathogens they carry occur,” Combes said.
Missouri remains a hotbed of tick-borne diseases, including Rocky Mountain spotted fever, ehrlichiosis, tularemia and Bourbon virus. Other newly emerging diseases, such as the Heartland virus, were first identified in Missouri just over a decade ago.
The research team plans to post weekly maps of tick specimens and abundance over the course of the two-year project.
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