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Magic Pill? Preventing Tick-Borne Diseases in Human Beings by George Shiflet Copyright © 2024 George Shiflet. All rights reserved.

See “Ticks: Well-Adapted Parasites” for information on various structural and physiological adaptations that make ticks successful parasites.

See “A Closer Look at Lyme Disease” for information on Lyme disease and recent research into chronic Lyme disease.

Ticks are small, eight-legged creatures that are not only annoying, they are important carriers (vectors) of various diseases of human beings, e.g., Lyme Disease, Rocky Mountain Spotted Fever, etc. (See Table 1). This parasite also may feed on your pet dog or livestock. In fact, ticks sicken livestock, costing farmers/ranchers billions each year. You may already give your pet a flavored, chewable pill to prevent ticks. Could such a pill be used in human beings? Perhaps.

Table 1.  Tick-Borne Diseases Common to the U.S.

Currently, there are a few things you can do to prevent ticks from using you as a host. You can avoid areas that might harbor ticks (e.g., locations with a deep litter layer (retains moisture), tall grasses and shrubs). Furthermore, you might wear long pants and shirts, closed shoes, use DEET-containing repellent, or treat your clothing with the repellent Permethrin (CDC 2024). Even if you wear protective clothing, you’ll need to check yourself carefully for ticks. Wouldn’t it be nice to take a pill to protect you against them attaching at all?

There is much research on developing a vaccine against ticks. Usually, the vaccine will function to manipulate your immune system to fend off ticks. There are protein factors in tick saliva that promote the passage of disease microbes, and vaccines may be generated that inhibit the action/activity of these protein factors. For instance, certain proteins allow the tick to feed, such as those that form a cementing cone for anchoring the tick to the wound. Thus, a vaccine containing this protein could be used to stimulate the production of antibodies against the protein. Subsequently, a tick that employs this protein would not be able to anchor well for feeding and disease transmission. However, ticks do not all have the same form of a target protein, so ticks that have a variant of that protein might be able to anchor properly. Nevertheless, such efforts are still worthwhile.

Recently, a pharmaceutical company announced an alternative against ticks for domestic animals and pets (Tarsus 2024). Lotilaner, produced by Tarsus, is already being used in cats and dogs to repel and kill ticks and fleas effectively. Moreover, in human beings, the drug is used in eyedrops for infestations of mites and in a very small, clinical trial against ticks. The company released results from this trial that gives hope the same medicine is effective at killing ticks. Early-stage ticks not carrying disease organisms were placed on the skin of human volunteers one day before dosing with an oral version of Lotilaner and 30 days after dosing. These tests were double-blind and placebo controlled. Two dosages (high and low) were tested, and both yielded greater than 90% kill rates for the ticks at 24 hours. Moreover, the percentages of tick mortality dropped little at thirty days. The drug was also tolerated well by the human hosts. Effectiveness lasting 24 hours is important, as often it requires 36+ hours for a tick to transmit a disease organism to the host. Research continues on this and other drugs against this dangerous parasite.

References

CDC.  “Preventing Tick Bites.” 2024. https://www.cdc.gov/ticks/prevention/index.html.

Tarsus. “Tarsus Announces Positive Topline Results from Carpo, a Phase 2a Proof-of-Concept ‘Tick-Kill’ Trial Evaluating TP-05 (lotilaner) for the Prevention of Lyme Disease,” Company Announcement. February 22, 2024.