New research shows (long-term) promise for eradicating tick-borne disease

2019-9-12 iStock-965394830 tick saliva - blog.jpg

Ticks can transmit a number of diseases to both pets and people through their saliva, including Lyme disease, Rocky Mountain Spotted Fever, Ehrlichia canis, and tick paralysis.

Currently, tick-borne diseases in pets and people are most commonly treated with the antibiotic Doxycycline, but promising new research out of Louisiana State University (LSU) aims to fight tick-borne pathogens at their root cause—saliva. The LSU researchers say certain compounds can dry up ticks’ saliva by upsetting the balance of ions in the salivary gland, reducing feeding and potentially limiting pathogen transmission.

“Lyme disease is exploding in the northeastern US” said Daniel Swale, PhD, assistant professor of insect physiology and the project’s principal investigator. “Most methods to kill ticks in the agricultural sector involve the use of neurotoxic insecticides, but it’s difficult to effectively use these insecticides to control ticks in residential areas. So we wanted to identify a new way to control these disease-carrying ticks.”

Swale and his colleagues figured that if they could stop ticks from producing saliva, then they could prevent them from feeding. And if the ticks couldn’t feed, they couldn’t survive—and they couldn’t transmit disease, either.

The research team fed ticks bovine blood laced with compounds known to affect their salivary glands. Two were effective, reducing saliva secretion by 95% or more and reducing blood ingestion by approximately 15-fold. More importantly, ticks who consumed either of those compounds died within 12 hours. That timeframe is significant because transmission of pathogens via ticks’ saliva into their human or animal hosts typically takes at least 12 hours and sometimes as many as 40 hours.

Next, Swale and his colleagues plan to test whether their treatment can in fact prevent pathogen transmission when ticks feed on rodents.

“This work is in the beginning stages of science,” Swale told NEWStat, and stressed that “means that we’re aiming to validate a target site and identify chemical scaffolds that are capable of giving us a phenotype that we want, which in this case is no blood feeding and death of ticks.”

“There are real world implications to this work because inhibiting salivary gland function in ticks should inhibit blood feeding and transmission of bacterial and viral pathogens,” Swale said, emphasizing that their research is purely speculative at this point because data on pathogen transmission is limited. “But we do know that [chemical manipulation of ticks’ salivary glands] prevents salivary gland function, prevents blood feeding, and causes mortality within 12 hours.”  

“I don’t know what type of impact it would have to current medication in dogs,” Swale said. “We haven’t studied this yet.”

“[But] this work is necessary for the eventual development of novel products to control ticks and their vectored pathogens.”

And that’s a pretty good start to eventually stop ticks from spreading disease.

Photo credit: © iStock/H_Barth