KERRVILLE, TEXAS (RFD NEWS) — New World screwworm cases are expanding beyond the first detection in Zavala County, prompting a larger livestock response from Texas and the USDA. Officials say confirmed cases now include multiple Texas animals and one case tied to New Mexico.
Texas Governor Greg Abbott and USDA Secretary Brooke Rollins updated producers on Monday at the Knipling-Bushland U.S. Livestock Insects Research Laboratory. The response includes quarantine zones, movement controls, expanded trapping, wildlife surveillance, and sterile fly releases.
USDA is dispersing sterile flies across affected areas and recalibrating release zones as detections change. Texas has also activated its emergency response structure and is coordinating reports through state animal health and wildlife agencies.
For ranchers, the immediate job is daily inspection. Producers should watch for draining wounds, maggots, foul odor, or discomfort, especially around newborn animals’ navels.
Officials say the food supply remains safe, and screwworm does not spread from animal to animal like a virus. Quick reporting will determine how fast the outbreak can be contained.
Canada and U.S. States Halt Cattle Imports from Texas
The response to New World screwworm continues to intensify as additional states and international trading partners roll out livestock restrictions, federal officials accelerate research efforts, and producers across the country remain on high alert following multiple detections in Texas.
Canada has now banned livestock imports from Texas. Canadian food officials say animals originating from Texas that were within 21 days of crossing the border will not be permitted entry into the country.
Livestock economist Derrell Peel says the move is largely political and is not expected to have a significant impact on overall trade flows.
Several U.S. states have also tightened import requirements. Florida, Georgia, Tennessee, and Montana have implemented additional veterinary requirements for livestock entering from Texas as animal health officials work to prevent further spread of the pest.
Rollins Tours Texas Research Facility
Agriculture Secretary Brooke Rollins traveled to Texas this week to review ongoing research and eradication efforts.
During her visit, Rollins toured the Knipling-Bushland Livestock Insects Research Laboratory in Kerrville, where researchers are working to expand sterile fly production and develop new tools to combat New World screwworm.
The facility recently developed a new sterile fly strain that officials say can double fly production output. The laboratory, operated by USDA’s Agricultural Research Service, studies a variety of livestock pests but has significantly expanded its screwworm research efforts as detections increase.
Rollins also highlighted USDA’s New World Screwworm Grand Challenge, a program launched last year that committed up to $100 million toward innovative private-sector solutions designed to strengthen eradication efforts and increase sterile fly production.
“Last year, USDA launched our New World Screwworm Grand Challenge, investing up to $100 million in innovative solutions from the private sector to strengthen eradication efforts and expand sterile fly production,” Rollins said. “We have spent the last couple of months reviewing over 226 applications through the Grand Challenge, and later this week we will begin rolling out some of those innovations.”
According to Rollins, USDA plans to announce new technologies and strategies in the coming weeks as part of an accelerated response effort.
Debate Emerges Over Screwworm Suppression Strategies
Texas Agriculture Commissioner Sid Miller continues urging USDA to deploy the Screwworm Adult Suppression System, or SWASS, as part of the response effort.
The system uses attractants, bait, and insecticides to reduce adult screwworm populations.
However, USDA officials say SWASS is not suitable for the current situation. The agency notes that the insecticides used in the system would also kill the sterile flies currently being released as part of eradication efforts. Officials also point out that prior testing was conducted only in relatively small areas and that the system cannot be used near rivers or other open-water environments.
Miller argues SWASS played a role in previous eradication campaigns, but USDA notes the technology was not deployed until the late 1970s, after New World screwworm had already been eradicated from the southeastern United States.
Producers Urged to Remain Vigilant
Livestock organizations continue encouraging producers to closely monitor their animals for signs of infestation.
The Kansas Dairy Association says recent detections were not entirely unexpected, given the growing number of cases reported in Mexico throughout the spring.
“There has been so much activity on the other side of the border in May already, with a whole summer in front of us, so it’s not a real shock,” said Chelsea Good with Kansas Dairy. “People are already on the lookout, and people are clearly ready to move on it.”
Good said one of the confirmed cases involving a calf’s umbilical area serves as an important reminder that producers should closely monitor newborn animals.
She credited producers for identifying potential problems early and submitting samples for testing before the situation became more widespread.
“They were being vigilant. They were looking for signs, they saw something, and so they sent it into the lab for testing,” Good said. “Between industry and our state and federal animal health officials, I think we had some extra time to get prepared, and that’s a good thing.”
Good also emphasized that New World screwworm is an animal health issue, not a food safety issue.
Veterinarians Address Prevention Questions
With one confirmed case involving screwworm larvae found in a calf’s umbilical cord, veterinarians say producers have been asking whether iodine treatments can help prevent infestations.
Dr. D.L. Step with Boehringer Ingelheim says iodine should continue to be used for its intended purpose of reducing bacterial infections in newborn calves and during certain veterinary procedures, but cautioned that its protective effects are short-lived and should not be viewed as a standalone screwworm prevention tool.
Veterinarians note that several medications currently have an Emergency Use Authorization for screwworm prevention and treatment. Producers are encouraged to work with their veterinarians to determine the best option for their operation.
Pet Owners Also Being Warned
Officials continue stressing that New World screwworm is not limited to livestock.
One of the latest confirmed cases involved a dog that had recently been in Mexico, highlighting concerns about the potential movement of the pest through companion animals.
Rollins says USDA is taking additional steps at the border to address that risk.
“This is not just a livestock issue. It’s not just a cattle issue. It is a pet issue as well,” Rollins said. “We have deployed additional trained USDA dogs down to the border that will be working with all crossings and all pets that are crossing.”
USDA officials say surveillance, sterile fly releases, border inspections, and producer vigilance will all remain critical components of the response as efforts continue to prevent further spread of New World screwworm within the United States.
