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Nov. 2, 2026 Source: Texas A& M As New World screwworm (NWS) continues to threaten animals in the U.S., Texas A&M University researchers are turning to the parasite's genetics to better understand where it comes from, how it changes and whether it could become resistant to the drugs used to control it. A team led by scientists at the Texas A&M College of Veterinary Medicine & Biomedical Sciences (VMBS), in collaboration with Texas A&M AgriLife and animal health experts in Honduras, has received approximately $4 million in funding through the U.S. Department of Agriculture's New World Screwworm Grand Challenge for a two-year project that will use samples from the ongoing outbreak in Honduras to develop new tools for tracking and controlling the parasite. The project, "Applying Lessons from the Honduras New World Screwworm Outbreak to Strengthen U.S. Preparedness," will combine expertise in parasitology and genomics to study thousands of individual screwworms, creating what researchers expect to be the most comprehensive genomic analysis of the parasite to date. NWS is a parasitic fly whose larvae, or maggots, infest wounds and feed on the living tissue of warm-blooded animals. Infestations can cause devastating wounds and, without prompt treatment, can be fatal. "It doesn't discriminate," said Dr. Guilherme Verocai, an associate professor in the VMBS Department of Veterinary Pathobiology (VTPB) and director of the Parasitology Diagnostic Laboratory. "It will infest pretty much any living, warm-blooded animal." Cattle are among the species most affected, but NWS can also infest horses, sheep, goats, pigs, pets, wildlife and humans. The parasite was eradicated from the U.S. through a decades-long effort that began in the 1950s and eventually pushed screwworm populations south through Mexico and Central America to a biological barrier in Panama. Beginning in 2021 and 2022, however, cases began increasing again in Panama. Within a few years, the outbreak had moved north through Central America and Mexico before reaching the U.S. in June 2026. Looking at the whole genome Verocai began building relationships with animal health officials in Honduras before NWS reached the U.S. Representatives from Honduras' National Service of Agricultural Health & Food Safety, the country's counterpart to USDA, visited Texas A&M in late 2025 for a meeting hosted by Texas A&M AgriLife. Those conversations opened the door to a collaboration when USDA later announced its New World Screwworm Grand Challenge. Through that collaboration, researchers will have access to screwworm samples collected throughout the Honduran outbreak, along with information such as when and where they were collected, which species they infested and, when available, how the animals were treated. The team will use those samples to examine how screwworm populations are related across different locations and points in time. Joining Verocai on the project are co-principal investigators Dr. Brian Davis, an assistant professor in VTPB; Dr. Rafael Ramos, a postdoctoral research associate in VTPB, and Dr. Sarah Hamer, a professor in the VMBS Department of Veterinary Integrative Biosciences. Davis, a geneticist on the project, said previous genetic studies of NWS have largely focused on specific genes researchers suspected could play roles in traits such as drug resistance. This project will take a much broader approach. "We can sequence 99.99% of the screwworm genome in every single individual across time and across space," Davis said. "That gives us a really powerful computational approach." Using Texas A&M's High Performance Research Computing resources, the researchers plan to compare whole genomes from thousands of individual screwworms. The scale will allow them to search for genetic similarities and differences that smaller studies could miss. "It's going to be by far the largest genetic study of screwworm ever," Davis said. Searching for signs of drug resistance That genomic data could help researchers determine whether NWS populations carry genetic markers associated with resistance to the drugs used to prevent and treat infestations. Although researchers do not yet know whether screwworms involved in the current outbreak carry those markers, drug-resistant populations have previously been reported in endemic areas of South America. By pairing genomic information with details about where samples were collected and, when available, how the animals were previously treated, the researchers hope to identify patterns that could indicate reduced susceptibility to certain drugs. "We hope to develop a validated molecular test that will screen screwworm for drug resistance markers," Verocai said. "That test could remain available and potentially be implemented in the U.S. or across endemic countries." Verocai said information from veterinarians responding to cases in Honduras could provide another piece of that puzzle. If they report that a particular treatment appeared less effective, researchers could compare those observations with the genetics of screwworms collected from those cases. Building tools for future outbreaks The researchers expect the project's genomic database to have uses beyond understanding the current outbreak. By comparing the genetics of screwworms collected from different locations, researchers may eventually be able to determine how populations are related and trace where new outbreaks originated. "If there was a potential outbreak in Florida, we could understand how related it might be to what's going on in Texas," Verocai said. The data could also reveal whether portions of the screwworm genome remain consistent across populations, potentially identifying targets for future drugs or genetic control technologies. "We are going to produce the most comprehensive genomic analysis of the screwworm that we can use as a database to track new outbreaks and future outbreaks and to look back in time at how the population has changed or not changed," Davis said. Once the analyses are complete, the genomic data will be made available to other researchers, allowing scientists in the U.S., Central America and elsewhere to build on the work and explore additional approaches to controlling the parasite. For Davis, that broader impact is an important part of the project. "We're here to help solve a pretty big problem," he said. "Hopefully, we can provide information to advance control mechanisms." Tweet |
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