COLLEGE STATION, Texas – Adela Oliva Chavez, Texas A&M AgriLife Research Entomologist and Assistant Professor at the Texas A&M College of Agriculture and Life Sciences Department of Entomology, Bryan-College Station, grew up in a farming family in Honduras and learned how to tick off at a young age can affect human and animal health.
Her experience in beef and milk production and as a playful child shaped her interest in science and continues to fuel her passion for making scientific breakthroughs that prevent or prevent tick-borne diseases such as Lyme disease and human granulocytic anaplasmosis and Texas cattle fever can treat, or bovine babesiosis, in farm animals.
“I’ve seen cows unable to get up because of severe anemia, so from a young age I was interested in doing something to solve this problem,” she said. “I went outside and played and I came home covered with ticks, and back then there wasn’t a lot of information about tick-borne diseases.”
Her sister developed a severe fever after an outing and was diagnosed with a mosquito-borne virus, but Chavez now suspects it might be related to a tick bite.
A career to solve both human and animal diseases. Chavez focused her early education and career on agriculture and animal health. Since then, she has been committed to finding scientific solutions and creating tools to control tick-borne diseases that cause significant human and animal problems and economic losses around the world.
Now she is at the forefront of the fight against diseases spread by these parasites. Her latest research was recently published in Nature Communications. She has also been appointed to a multidisciplinary group of 50 young academics from around the country working on various global threats related to the impact of animal diseases on human health.
The likelihood of pathogens being transmitted from the parasite to the host has increased over the past two decades, according to the Centers for Disease Control and Prevention with tick populations. The total number of tick-borne diseases more than doubled to 50,865 in 2019, compared to 22,257 in 2004.
Lyme disease, the most common tick-borne disease in humans, affects an estimated 476,000 Americans annually, based on insurance records. This leads to costs between $ 712 million and $ 1.3 billion, according to the John Hopkins Bloomberg School of Public Health.
In animals, bovine anaplasmosis, a disease caused by a bacterium carried by several species of ticks, costs ranchers an estimated $ 300 million annually. The overall impact of ticks on livestock farming is likely to be even greater because it is difficult to measure the parasite’s impact on cattle weight, decreased milk production, abandoned calves, or other health problems that reduce production.
Chavez said the numbers of people infected with vector-borne pathogens transmitted by ticks are also likely to be much higher than the CDC estimates due to misdiagnosis and low reporting rates in mild cases. Bites can cause serious health problems in healthy hosts and poor health outcomes in immunocompromised individuals.
Winning the war against ticks. The bite site is Chavez’s new focus. Her research, presented in Nature Communications, showed that changes at the molecular level occur when ticks feed and affect the immune response and the host’s ability to fight pathogens.
Feeding ticks can be a long process that can take several days, she said. At some point during feeding, ticks will pass the pathogen while repeating a cycle of saliva injections and blood sucking.
In this transfer sequence, Chavez believes that micro-RNA and proteins are transferred from the tick to the host in order to manipulate the immune response so that the tick can feed. A reduced immune response prevents body reactions such as blood clotting, wound closure and any direct immune counterattack against the parasite.
“These pathogens do more than just ride the tick,” said Chavez. “Pathogens and ticks form a symbiosis that is more than 100 million years old. It is really an arms race. The tick bites and the host’s immune response tries to kill the tick and a fight ensues. The pathogen, which has adapted to the use of the tick as a vessel, works symbiotically with it in this fight to disrupt the host’s immune response and enable the tick to eat. “
By learning which specific cell types or immune signaling pathways are activated during the response to the tick bite, Chavez and other scientists hope to improve the immune response to stop or treat infection by tick-borne pathogens.
“The end 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 farms in the US and around the world.”
Reducing the effects of ticks. There are hundreds of types of ticks and ticks can be found on every continent. All ticks feed on blood, but there is great diversity between species, including their feeding processes and the diseases they carry.
Available vaccines target some types of ticks that are economically important to farm animals, but effectiveness may be limited in controlling ticks from different strains, Chavez said.
The U.S. Department of Agriculture and its Animal and Phytosanitary Inspection Service are funding a project focused on developing better vaccines. Chavez began working on this project in 2019, purifying material that she expects to begin studies in the USDA facilities in October or November.
Chavez and other entomology scientists at Texas A&M AgriLife are also studying epigenetic similarities and differences in tick populations. By identifying epigenetic markers found in local ticks, health officials can track traits, behaviors and pathogens in these populations.
For example, how and where the tick is on the vegetation while waiting for a host or “looking” seems to be inherited from the tick’s parents. Different populations of ticks from southern parts and northern parts of the country look for differently, Chavez said.
The search difference is a hypothesis of why Lyme disease isn’t as prevalent in Texas as it is in northern parts of the country, including Minnesota, where partner scientists share data found through tick research.
“Lyme disease occurs here and all over the south, but ticks don’t grow as high in vegetation as strains of the same tick species do in the Midwest,” said Chavez. “They do not transmit so much to humans or acquire pathogens.”
Studying these epigenetic markers could also be crucial for prevention, she said.
Research focused on ticks is becoming increasingly important, Chavez said, as species expand their range due to warmer weather patterns and higher numbers of potential hosts, such as deer. These efforts are also vital to preventing invasive species of ticks, such as the bovine fever ticks, which are found in parts of southern Texas and are particularly fatal to cattle, from causing catastrophic losses in the United States
“Ticks are not a new problem, but more attention has been paid to them over the past 20 years, particularly their effects on humans,” said Chavez. “But whether it’s food sources, livelihoods, or human health, it is important that we learn more about ticks in order to reduce their impact.”
