By Jennifer Whitlock
Field Editor
One Texas A&M AgriLife Research entomologist is fulfilling a lifelong interest in human and animal health by focusing on one tiny creature—the tick.
Growing up on a farm in Honduras, Adela Oliva Chávez, assistant entomology professor at Texas A&M University, was fascinated by the issues her family and livestock encountered after exposure to ticks.
“I’ve seen cows unable to stand up because of severe anemia, and so I was interested at a very young age to do something to solve this problem,” Chávez said. “I would go outside and play and come home covered in ticks, and back in those days, there wasn’t much information about tickborne diseases.”
Her sister was once diagnosed with a mosquito-borne virus, but after she learned more about the parasitic critters, she thinks the disease was likely from a tick bite instead.
Now, her research centers on tickborne illnesses such as Lyme disease and human granulocytic anaplasmosis in humans and bovine anaplasmosis and bovine babesiosis in livestock.
Her interest dovetails with a rise in tickborne diseases, which data from the U.S. Centers for Disease Control and Prevention show have risen sharply in recent years—from about 22,000 cases in 2004 to more than 50,000 in 2019. Chávez noted the actual number of people infected is probably much higher because tickborne illnesses are often underreported and misdiagnosed.
When it comes to human health, Lyme disease is estimated to affect almost 500,000 Americans each year, costing up to $1.3 billion annually to treat, according to a report published in 2015 by Johns Hopkins researchers.
In livestock, the economic impact of tickborne infections is so great it has never been accurately measured. But a 2018 global study indicated Rhipicephalus microplus, or cattle fever ticks, may have the greatest economic impact with estimated losses exceeding $13 billion per year worldwide.
“Ticks are not a new problem, but there has been more attention on them over the last 20 years, especially on their effects on humans,” she said. “But whether it’s affecting sources of food, or livelihoods or human health, it is important that we learn more about ticks to reduce their impact.”
In her latest research published in the science journal Nature Communications, Chávez demonstrated that distinct changes occur at a cellular level in hosts to promote bacterial infection based on the species of tick parasite.
Another area of study for the researcher is epigenetic markers, like characteristics and behaviors, in tick populations across the country. Epigenetics may hold the key to determining why Lyme disease is more prevalent in northern portions of the U.S. than Texas, for example.
How the tick situates itself on vegetation while waiting for a host, known as questing, appears to be an inherited trait. Populations from the northern and southern U.S. quest differently, which led her to believe there may be a link between that behavior and Lyme disease transmission.
If researchers can figure out why, she said it could help them develop further ways to prevent tickborne infections in the first place.
“The final product would be a vaccine that would make the host immune to the tick and kill the tick before it passes a pathogen,” she said. “My goal is to find tools that prevent disease and are affordable for individuals and small farming operations in the U.S. and around the world.”
Although there are livestock vaccines available for some tick species, she noted efficacy is limited when attempting to control a variety of species at once.
To develop better animal vaccines, Chávez began working on another research project through the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service in 2019. Trials are expected to start later this fall.
Summer is a traditional time of higher exposure to tick bites, so those working or participating in recreational activities outdoors are advised to wear hats, long-sleeved shirts and pants in light colors. More information is available here.