Texas A&M Researchers Map Tick Habitat to Strengthen African Swine Fever Preparedness

DHS-funded study examines if a long-lived soft tick in Texas might transmit African swine fever which would impact the response, surveillance, and outbreak control.

A small, nest-dwelling tick found across large parts of Texas could play an outsized role in how the United States responds to African swine fever (ASF) should the virus ever reach domestic or wild pigs.

In a recent study, researchers at the Texas A&M College of Veterinary Medicine & Biomedical Sciences (VMBS), Texas A&M AgriLife Research, and the Department of Biology mapped where Ornithodoros turicata — a soft tick species native to Texas and the southwestern United States — is most likely to survive and examined what that means for ASF preparedness.

The study is part of a $1.4-million, Department of Homeland Security-funded research project through the Cross-Border Threat Screening and Supply Chain Defense (CBTS), DHS Science and Technology Directorate (S&T) Center of Excellence housed at Texas A&M. Led by Dr. Meriam Saleh, a clinical assistant professor in VMBS’ Department of Veterinary Pathobiology, this project seeks to understand whether Texas-derived populations of the tick could help sustain or transmit the virus if it were introduced into the U.S. — and how that risk could affect the food supply, trade, and cross-border livestock movement. By supporting research at the intersection of animal health, border security, and supply chain resilience, CBTS helps address emerging transboundary threats before they escalate into large-scale economic or homeland security challenges.

The study is co-led by Dr. Dee Ellis, a veterinarian in AgriLife Research and the Department of Entomology. Ellis focuses on the industry and stakeholder impacts of the virus. Though ASF is not currently in the U.S., it is present in the Caribbean, Europe, Africa, and parts of Asia. This virus is highly contagious in pigs and often fatal, making it one of the most economically devastating livestock diseases in the world.

“It’s on our doorstep,” Saleh said. “Even though introduction isn’t probable, it’s possible — and because the consequences are so severe, it warrants serious attention.”

A $50 Billion Industry at Risk

In countries where ASF has been introduced, outbreaks have led to mass depopulation of herds, long-term trade restrictions, and billions of dollars in losses.

The U.S. pork industry contributes more than $50 billion annually to the national gross domestic product and supports more than 550,000 jobs across production, processing, and export sectors. The U.S. is one of the world’s leading pork exporters, and international trade depends heavily on disease-free status.

If ASF were detected in the U.S., immediate export bans and large-scale control measures would likely follow.

“Because the implications are so severe, even a low-probability risk deserves close scrutiny,” Saleh said.

Why This Tick Matters

ASF spreads primarily through direct contact between infected pigs, contaminated feed or meat products, and infected environments. However, in parts of Africa where the virus is endemic, it is maintained in wildlife through soft ticks in the same genus as O. turicata.

Unlike the hard ticks most people encounter on pets or in tall grass, soft ticks behave differently. They live inside animal dens and burrows rather than on vegetation. They feed quickly — often for less than an hour — and then retreat back into crevices.

“These ticks are very sneaky,” Saleh said. “They feed at night, they can survive for years waiting for another blood meal, and most notably, they can live for 10 years or more”

If ASF were introduced into pig populations and also infected local tick populations, those long-lived ticks could allow the virus to persist even after infected animals are removed.

“Even if you depopulate infected pigs, infected ticks could reintroduce the virus when new animals are brought in,” Saleh said.

Predicting Where the Tick Could Survive

To better understand that risk, the research team used ecological range modeling to predict where environmental conditions are favorable for O. turicata — information that can help guide surveillance planning.

The model identified most of Texas — except for the eastern portion — as a suitable habitat. It also suggested potential northward expansion and highlighted highly suitable areas in Southeastern Georgia, where the tick has not yet been documented.

Average temperatures during the warmest months and moisture levels during the wettest periods were among the most influential environmental factors shaping suitability.

The findings also help inform where laboratory testing and field collection efforts should be prioritized as part of the federally funded research initiative.

For example, long-term changes in temperature and moisture patterns could alter where the tick can survive.

“We could see expansion into new areas,” Saleh said. “But it’s not just the tick responding to environmental conditions — changes in wildlife host availability could influence whether tick populations expand, contract, or move geographically.”

Understanding those dynamics is critical for anticipating future risk zones.

Surveillance and Preparedness

The study also emphasizes the importance of proactive, strategically targeted surveillance — particularly along the U.S.-Mexico border and in regions with dense swine or wild hog populations. This includes identifying where the tick occurs and refining effective sampling methods.

Because soft ticks live inside burrows and dens, they are difficult to detect using traditional methods. Researchers instead use carbon dioxide-baited traps placed in wildlife burrows to mimic a host’s breath and attract ticks.

Access to private land, weather conditions, and the need to avoid disturbing natural habitats all complicate detection efforts.

“A lot of tick surveillance is passive or by chance,” Saleh said. “By the time you know there’s a problem, it’s already been happening for months.”

Implications For Outbreak Control

If ASF were introduced, pig-to-pig transmission would likely drive early spread. However, the presence of competent tick vectors could extend the duration of an outbreak and complicate eradication efforts.

“The tick would contribute more to persistence than large-scale spread,” Saleh said. Ellis adds that “the ticks could serve as a long-term reservoir for reintroduction of ASF into feral swine or backyard swine populations.”

Wild hog populations add another layer of complexity. Feral swine are widespread and difficult to control, potentially serving as amplifying hosts and bridging domestic and wildlife populations.

In parts of South Texas, the presence of free-ranging African warthogs — the natural wildlife reservoir in endemic regions — further elevates concern.

“That’s a big concern because warthogs can have the virus and not be sick,” Saleh said. “That ups the ante.”

The team’s ongoing research is examining whether Texas-derived O. turicata ticks can transmit ASF under natural feeding conditions and how long the virus may persist within tick populations. Establishing laboratory colonies and studying virus persistence will help researchers determine whether ticks could serve as long-term reservoirs if the virus were introduced.

While the likelihood of introduction remains uncertain, the consequences would be significant. By mapping where that tick could survive and refining how to detect it, researchers are helping ensure the U.S. is better prepared before a crisis ever begins. The study demonstrates the importance of sustained interdisciplinary research programs that connect veterinary science, environmental surveillance, border preparedness, and supply chain protection to address evolving cross-border biological threats.

This project has been funded in part with federal funds from the Department of Homeland Security under BOA No. 70RSAT21G0000001, task order no. 70RSAT24FR0000100 through the Cross-Border Threat Screening and Supply Chain Defense (CBTS) DHS S&T Center of Excellence. The content of this publication does not necessarily reflect the views or policies of the Department of Homeland Security, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.