You don't have to worry about Lyme disease with these ticks, but they can still pose a threat to humans.

By Leah Groth
September 11, 2020
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Summertime is pretty much synonymous with ticks—specifically blacklegged ticks which can cause Lyme disease. But new research has found that more people in the US have another tick to watch out for, too: 'soft' bat ticks.

The study, published on September 9 in the Journal of Medical Entomology, identified that these bat ticks have been found in New Jersey for the first time, specifically in Mercer and Sussex counties. Scientists from the Endangered and Nongame Species Program of the Division of Fish and Wildlife in the New Jersey Department of Environmental Protection discovered the presence of the ticks in New Jersey—via tick larvae found on big brown bats (Eptesicus fuscus)—last year

Though bat ticks are already a known presence in 29 of the 48 contiguous US states—including Iowa and Minnesota—their discovery in New Jersey could signal that the ticks are becoming more common, senior study author Dina M. Fonseca, a professor and director of the Center for Vector Biology in the Department of Entomology in the School of Environmental and Biological Sciences said in a Rutgers University press release. Here's what you need to know about the 'soft' bat ticks—and whether they pose a health threat to humans.

What are bat ticks? 

Bat ticks, technically known as Carios kelleyi, are a species of soft ticks that feed on bats, like the name suggests. These "soft" ticks have a visibly soft or leathery body that hides their mouthparts, according to the press release, compared to "hard" ticks (like the infamous blacklegged or deer tick) which have a hard covering and visible mouthparts. 

All ticks technically feed on blood, but bat ticks specifically prefer to feed on bats, according to Iowa State University. That said, if no other option is available, bat ticks will feed on other mammals, including humans.

When bat ticks are present in a region, they're often found on bats that regularly roost in the cracks and crevices of attics, barns, or similar structures. The bat ticks normally stay close to their chosen bat hosts, per Iowa State University, but if the bats leave the area, the ticks may become hungry and search for a different food source.

Live larval bat ticks (Carios kelleyi) removed in 2019 from big brown bats in Mercer County, New Jersey.
J. Occi/Rutgers Center for Vector Biology

How dangerous are bat ticks to humans?

While it has been well-established that ticks can spread disease—the most common being blacklegged or deer ticks, which are vectors for Lyme disease—the dangers of bat ticks is not as widely understood. The study does point out that in other states, C. kelleyi has been found infected with microbes that are harmful to people, pets and livestock. 

Lead author James L. Occi, a doctoral student in the Rutgers Center for Vector Biology at Rutgers University-New Brunswick, explains to Health that while all ticks feed on blood and may transmit pathogens during feeding, there have been very few reports of bat tick borne illnesses and no reports of death as a result of a bite. 

“There are only one or two case reports,” he explains in an email, adding that there is no widespread data on this. He does point to a 2005 study where Carios kelleyi nymphs and adults were was found to have three genuses of bacteria that are often harmful to humans: Borrelia, Rickettsia, and Bartonella. “These bat ticks were found crawling in a home (walls, floor) that was cleared of its bats,” he says. 

The Centers for Disease Control and Prevention also list soft ticks as a vector for tick-borne relapsing fever, a rare infection linked to sleeping in rustic cabins, mainly in the mountains of the western US, caused by the Borrelia bacteria. The main symptoms are recurring high fever, headache, muscle aches, and joint aches, that typically last three days on, seven days, off and three days on—a process that can continue repeating for several cycles without antibiotic treatment.

How can you protect yourself against bat ticks?

First: Take note that the new study only found the presence of bat ticks in New Jersey, not any diseases associated with them. “The next steps are to collect more soft tick specimens and test them for disease-causing microbes,” Occi said in the press release.

Luckily, most people and their pets don’t come into contact with bats on a regular basis, so your chances of encountering one is extremely rare, but still possible. “Bat ticks feed almost exclusively on bats, but will try other sources if they need to,” he tells Health, offering a potential scenario where humans or pets could come into contact with bat ticks: Sometimes, bats can be found in your attic. Once you remove the bats, the ticks remain and need a food source, like humans. “They can go for months without feeding, but if they detect a host in the attic they may become aroused and seek the source of a potential blood meal.”

So, your best bet for protection: If you know of any winged night creatures living on your property, you should be incredibly careful, especially if you decide to remove them.

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