It’s Personal
When Sumi, an energetic Australian cattle dog mix, became unusually quiet and refused to eat, her owner, Sreekumari Rajeev, knew something was wrong. Now a microbiologist and professor in the Department of Biomedical and Diagnostic Sciences at the UT College of Veterinary Medicine, Rajeev was teaching at Ross University School of Veterinary Medicine in St. Kitts, West Indies, at the time. At the clinic where her husband practiced, they examined Sumi’s blood. They discovered her platelets were filled with bacteria, a telltale sign of Anaplasma platys, a pathogen transmitted by the brown dog tick. The disease can cause severe internal bleeding and, if untreated, can be fatal. Sumi recovered, but the incident left Rajeev determined to learn more. From Sumi’s blood, Rajeev’s lab has sequenced the first complete genome of A. platys, a bacterium that cannot be grown in the laboratory. Her team discovered unexpected similarities between the genomes of A. platys and Ehrlichia canis, another bacterium that causes life-threatening diseases in dogs.
With funding from the American Kennel Club Canine Health Foundation, what began as a desperate attempt to save her own pet has grown into groundbreaking research that could lead to the first effective vaccine against two serious tick-borne diseases in dogs.
A Resource When Things Go Wrong
After former Senator Kay Hagan of North Carolina died from Powassan virus, a rare tick-borne disease, Congress passed the bipartisan Kay Hagan Tick Act to strengthen the national response to vector-borne illnesses affecting human and animal health. The act supports the Centers for Disease Control and Prevention–funded VectorEd Network, led by Penn State University and including the University of Tennessee as a collaborator. Within this network, experts share research, education, and outreach resources to improve prevention and response strategies.
One major outcome of this effort is the VECTOR Library—the acronym stands for Vector Education, Communication, and Training Online Resource—which houses more than 1,400 educational materials from the Cooperative Extension System across the US. The searchable database allows users to filter resources by state, vector type, or audience, making it easier to find science-based information. At UTIA, Becky Trout Fryxell, professor of medical and veterinary entomology in the Department of Entomology and Plant Pathology, highlights the state’s challenges: blacklegged ticks transmit Lyme disease in the East, mosquitoes spread West Nile virus in the West, and Lone Star ticks, found throughout the state, are linked to alpha-gal syndrome. “It can get overwhelming and confusing to find science-based information on these diseases. The VECTOR Library now makes that information accessible,” she explains.
Using a transdisciplinary approach that integrates biology, ecology, genetics, epidemiology, and education, Trout Fryxell and her lab work to prevent, detect, and respond to vector-borne disease outbreaks. Their research and training efforts prepare the next generation of public health and veterinary science professionals to help communities prevent these diseases before they emerge.
Advancing the Fight Against Tick-borne Diseases
While ticks may be tiny, they carry pathogens that cause serious illnesses in people and animals. One of these diseases, human anaplasmosis, is the second most common tick-borne disease in the US. It’s caused by Anaplasma phagocytophilum, a bacterium spread through bites from infected blacklegged ticks (Ixodes scapularis). The same bacterium can also infect domestic animals, creating an expanding public and veterinary health concern.
Girish Neelakanta and Hameeda Sultana, professors in the Department of Biomedical and Diagnostic Sciences, are uncovering how this bacterium survives and spreads through ticks. They recently renewed their five-year, $1.8 million National Institutes of Health R01 grant, “Anaplasma phagocytophilum modulates tick gene expression for its survival and transmission from the vector host,” which began in July 2024.
Their earlier studies showed how certain tick proteins and the tryptophan metabolic pathway help A. phagocytophilum survive inside ticks and move to new hosts. Building on that foundation, their new work will test whether blocking key tick molecules can prevent transmission of the bacterium. Their research could lead to new strategies, such as anti-tick vaccines, to stop disease transmission before it occurs.
The Sultana laboratory is the first to show that arthropod exosomes (think of them as tiny delivery bubbles) from medically important vectors such as ticks and mosquitoes transmit flaviviruses such as Langat virus, Dengue/Zika viruses, or West Nile virus to the vertebrate host. These studies are important in that they might change the way we think about the approaches and strategies to interfere with the modes of pathogen transmission from vector to humans and animals.
Call of the Wild
Coyotes, meanwhile, are helping scientists track these expanding threats. As adaptable predators that thrive in both wild and urban environments, they serve as valuable sentinels for emerging diseases. Eliza Baker, a PhD student in comparative and experimental medicine, led a recent study published in the Journal of Wildlife Diseases titled “Survey of Coyotes for Vector-Borne and Bacterial Pathogens in South Carolina and Tennessee.” Her team tested coyotes for several pathogens transmitted by ticks, mosquitoes, and water—including Borrelia burgdorferi (Lyme disease), Ehrlichia, Anaplasma, Dirofilaria immitis (heartworm), and Leptospira species.
Coyotes in Tennessee showed much higher exposure rates than those in South Carolina: 66 percent tested positive for Ehrlichia, 43 percent for Lyme disease, and 26 percent for Anaplasma. One quarter were exposed to Leptospira, and three animals carried the bacteria in their kidneys. Nearly five percent of the blacklegged ticks collected from Tennessee coyotes carried B. burgdorferi, confirming that Lyme disease continues to spread deeper into the Southeast.
As climate and habitat shifts expand tick populations, the diseases they carry are following. Coyotes offer a vital window into how these pathogens move through ecosystems.
By studying wildlife, researchers gain insight into the shared health of wildlife, domestic animals, and humans, a core principle of the One Health approach. Their findings underscore the importance of continued tick and wildlife surveillance to better predict and prevent the spread of disease across species and regions.
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