A new device may offer a better way to prevent tick bites

A new device may offer a better way to prevent tick bites

Označeno: Novi uređaj može ponuditi bolji način za sprječavanje ugriza krpelja

Controlled Release Device (CRD). credit: FLAT ONE (2022). DOI: 10.1371/journal.pone.0269150

When it comes to preventing tick bites—especially in light of the dramatic, decades-long rise in tick-borne diseases—bug sprays help, but are less than optimal.

For example, DEET is designed to prevent fast-moving mosquitoes from landing on their host, where they bite and fly away in seconds. Ticks, on the other hand, do not fly, but rather work from an ambush, then slowly climb up their host until they embed, feed, and can stay for days.

“Unfortunately, most repellents were developed for mosquitoes 75 years ago and not for ticks” says vector-borne disease expert Stephen Rich, professor of microbiology at the University of Massachusetts Amherst and executive director of the New England New England Center of Excellence (NEWVEC) at UMass Amherst. “DEET, the gold standard, works pretty well, but the holy grail would was to have another repellent—not a contact repellent like DEET, but a spatial repellent—that works as well or better than DEET against ticks.”

Experiments in Rich’s medical zoology lab used a new controlled-release device developed by scientist-entrepreneur Noel Elman. Rich and colleagues tested the effects on ticks after releasing the synthetic pyrethroids transfluthrin and metofluthrin into a small, transparent chamber equipped with three vertical climbing rods. Ticks do not come into direct contact with repellents; instead, the active ingredients create more of a “force field” that alters and slows the tick’s progress toward the target.

Označeno: Novi uređaj može ponuditi bolji način za sprječavanje ugriza krpelja

Experimental setup. The controlled release device was placed in the upper left corner of the experimental chamber. Three vertical climbing poles were arranged along the upper side. The camera recorded tick climbing from the perspective shown for quantitative analysis of behavior based on vertical movement. credit: FLAT ONE (2022). DOI: 10.1371/journal.pone.0269150

The results, published today, November 8, in the journal FLAT ONEfound that two spatial repellents were effective in changing the behavior of ticks, making them less likely to climb vertically and more likely to detach or fall from the stick.

“While we still have a lot of work to do, these innovative findings prove the principle that these spatial repellents change tick behavior in a way that we hope will lead to fewer tick bites” says Rich, senior author.

The paper’s lead author, Eric Siegel, helped design a vision system that accurately tracked the ticks’ movements in the experimental chamber. “People often throw around the word ‘repellency,’ and we set out to redefine repellency in tick protection and find ways to measure it,” says Siegel, a lab technician who will begin Ph.D. studies in microbiology at Rich. “There’s so much of what we still don’t know about the smell of ticks [smell] and delicious [taste] mechanisms, and that was the biggest challenge in these experiments, as is generally the case in the development of protective products.”

The compounds were tested against three major ticks that bite humans in the US: I. scapularis (the black-legged or deer tick), which can spread Lyme disease and anaplasmosis, among other diseases; D. variabilis (American dog tick), which can transmit Rocky Mountain spotted fever and tularemia; and A. americanum (lone star tick), which can spread ehrlichiosis and is associated with red meat allergy.

Označeno: Novi uređaj može ponuditi bolji način za sprječavanje ugriza krpelja

Concentration gradient from CFD simulation, 25 minutes after release. Concentration gradients produced by CFD simulation are plotted for (A) transfluthrin and (B) metofluthrin, 25 minutes after release. Allowing for a 20-minute induction time prior to tick introduction, the concentrations represented tick exposure halfway (5 minutes) through the trial. A vertical concentration gradient was observed, with higher concentrations (warmer colors) present at the bottom of the chamber and lower concentrations (cooler colors) at the top. Two perspectives are illustrated: viewing the chamber from the perspective of the camera (right) and the side with the CRD (left). The CRD was positioned in the upper left corner of the right box perspective and the upper middle of the side perspective. credit: FLAT ONE (2022). DOI: 10.1371/journal.pone.0269150

Experiments revealed that transfluthrin deterred 75% of D. variabilis, 67% of A. americanum and 50% of I. scapularis. Metofluthrin was slightly more effective, deterring 81% of D. variabilis, 73% of A. americanum and 72% of I. scapularis.

“We were impressed not only by the repellency but also behavioral changes in a tick,” says co-author Elman, founder and CEO of GearJump Technologies, which designed a controlled-release device that can be attached to soldiers’ boots. Many ticks in the experiments became slower, less mobile and appeared to be in a “drunk state” , the paper states.

Elman approached Rich several years ago to design and conduct experiments using the device with various repellents. The next step is to perform experiments with real host animals.

“Repellents probably won’t stop ticks from attacking us,” says Rich. “Hopefully the repellents will help keep them from getting on us, and that’s where the battle lines need to be drawn.”

Researchers envision a day when such devices will be commercially available to the general population. Until then, the research will continue. “We still mostly don’t know how the chemicals we use work,” says Siegel. “Once we do that, we can develop and improve these measures in a more targeted way.”

More information:
Eric L. Siegel et al, The spatial repellents transfluthrin and metofluthrin affect the behavior of Dermacentor variabilis, Amblyomma americanum, and Ixodes scapularis in an in vitro vertical climbing test, FLAT ONE (2022). DOI: 10.1371/journal.pone.0269150

Citation: New device may offer better way to prevent tick bites (2022, November 8) Retrieved November 9, 2022 from

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