New World Screwworm: Fact Sheet & SHIC Article 6/10/2026 & USDA NWS Website & SHIC/AASV NWS Webinar (8/4/2026)
New World Screwworm: Fact Sheet & SHIC Article 6/10/2026 & USDA NWS Website & SHIC/AASV NWS Webinar (8/4/2026)
Preparedness—not panic—was the central message delivered during a Swine Health Information Center-sponsored webinar bringing together federal regulators, extension specialists, and animal health experts to help pork producers prepare for the potential impacts of New World screwworm. The webinar, presented in collaboration with the American Association of Swine Veterinarians on August 4, 2026, focused on response planning, regulatory pathways, available resources, and practical producer outreach. The webinar had 240 registrants with 159 individuals attending live from across 11 countries, and it is now available for on demand viewing.
Watch the webinar here.
While NWS has been detected in Texas and New Mexico, speakers emphasized that no cases have been identified in swine to date, and the pork industry has an opportunity to prepare before the parasite becomes a swine health issue. Throughout the program, presenters stressed the importance of early detection, prompt reporting, wound management, and coordinated response among producers, veterinarians, regulators, and extension personnel.
Find SHIC’s NWS fact sheet here.
New World Screwworm Response Built Around Rapid Detection and Eradication
Dr. Lindsey Holmstrom, director of national preparedness and incident coordination with USDA APHIS Veterinary Services, outlined the federal response strategy and emphasized several key facts producers should understand about NWS.
Unlike infectious diseases such as African swine fever or PRRS, NWS is a parasite rather than a virus. It does not spread directly from animal to animal, nor is it transmitted through meat, milk, or other animal products. Instead, adult flies lay eggs in wounds on warm-blooded animals, where larvae feed on living tissue.
Dr. Holmstrom noted that USDA confirmed the first US detection during the current outbreak on June 3, 2026, in a calf in Zavala County, Texas. USDA maintains a publicly available dashboard, updated daily, tracking all confirmed detections.
To support response activities, USDA developed a comprehensive New World Screwworm Response Playbook, providing a national framework that can be adapted by states while remaining flexible enough to incorporate new information and response experience as conditions evolve. The playbook focuses on eradication through surveillance, movement controls, treatment guidance, and coordinated response activities.
Among the important operational elements described by Dr. Holmstrom were:
Swine Husbandry Creates Opportunities for Vigilance
Although NWS has not been detected in pigs, Dr. Holmstrom explained that routine swine management practices can create wounds that could become sites for infestation.
Examples include tail docking, castration, ear tagging, ear notching, tattoos, post-farrowing wounds, pressure sores, tail biting, and injuries from aggressive interactions among animals.
Rather than asking producers to identify adult flies, USDA recommends focusing on frequent animal inspections and wound management. Because many fly species resemble screwworm flies—and sterile flies released during eradication efforts may also be present—identifying adult insects is not a practical surveillance strategy for producers.
Instead, producers should:
FDA Explains Regulatory Pathways for Animal Drugs
Amber McCoig, DVM, senior veterinary medical officer with FDA’s Center for Veterinary Medicine, reviewed the agency’s role in rapidly making treatment options available while protecting animal welfare and food safety.
Dr. McCoig explained that FDA is working closely with USDA APHIS, international regulators, industry, and pharmaceutical companies to facilitate product development while providing emergency access when appropriate.
She described several regulatory pathways available for NWS products, including:
One of Dr. McCoig’s most important messages concerned extra-label drug use. Only fully approved animal drugs may be used extra-label under veterinary oversight. Products available only through conditional approval or Emergency Use Authorization are not eligible for extra-label use unless specifically authorized. Likewise, products containing the same active ingredient are not automatically approved simply because another formulation has received authorization for NWS.
She also reviewed differences among product claims for treatment, prevention of myiasis, and prevention of reinfestation, noting that producers and veterinarians should carefully follow label indications because formulations, routes of administration, and intended uses are not interchangeable.
Dr. McCoig emphasized that FDA evaluates food safety for products used in food animals, establishing withdrawal times as needed to ensure pork entering the food supply remains safe. She cautioned that prolonged reliance on antiparasitic drugs alone is not a sustainable strategy because resistance has already been reported for some compounds, including ivermectin. Sterile insect release remains the cornerstone of long-term eradication.
EPA Reviews Emergency Pesticide Options
Representatives from the U.S. Environmental Protection Agency described how pesticide products may become available during emergency situations.
Dr. Eric Bohnenblust reviewed EPA’s emergency exemption process under Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), which allows temporary use of otherwise unregistered pesticide applications when urgent conditions exist and no effective alternatives are available.
He explained that EPA evaluates emergency requests through a multidisciplinary scientific review, considering biological effectiveness, human health, environmental impacts, and economic consequences before authorizing emergency use. For food-producing animals, EPA must also establish appropriate residue tolerances to protect consumers.
Dr. Bohnenblust also outlined the Section 24(c) Special Local Need registration process, which allows states to authorize additional uses of federally registered pesticides when local pest management needs cannot be adequately addressed through existing labels.
Texas Experience Highlights Importance of Producer Education
Jeff Wiegert, PhD, Texas A&M AgriLife Extension associate professor and extension specialist, concluded the webinar with observations from ongoing outreach efforts in Texas. He reported that as of August 3, 2026, no NWS cases had been identified in pigs, despite confirmed cases in other livestock species.
Dr. Wiegert described Texas’ swine industry as a mix of large commercial operations concentrated in the Panhandle and thousands of smaller show pig producers across the state. These smaller operations often feature mixed-species facilities, varying biosecurity practices, open-air housing, and frequent animal movement, creating unique educational challenges.
Among the most common questions extension personnel receive are whether concrete flooring interrupts the screwworm life cycle, whether producers should search for adult flies, and whether every maggot found in a wound is New World screwworm.
His answers were straightforward: Concrete does not eliminate risk because larvae can pupate anywhere protected and warm. Producers should focus on finding larvae rather than adult flies, which are rarely observed. And not every maggot represents NWS, making proper diagnostic submission essential.
Dr. Wiegert also noted that educating producers about quarantine terminology has required substantial outreach because many producers associate quarantines with highly contagious foreign animal diseases or COVID-19 restrictions. Extension, USDA, the Texas Animal Health Commission, and allied organizations have worked together to explain how movement controls differ for NWS.
Texas A&M AgriLife has developed an extensive library of preparedness resources, including online training modules covering screwworm biology, inspection procedures, treatment, movement requirements, and enforcement. County Extension agents remain the primary local resource for producer education, specimen collection, permitting assistance, and ongoing response support.
Links Shared by Dr. Wiegert
Agrilifeextension.tamu.edu/new-world-screwworm
Preparation Before Detection
Across every presentation, one consistent message emerged: Preparedness today will determine the effectiveness of tomorrow’s response.
Federal agencies have established response plans, regulatory pathways, and treatment authorizations, while extension specialists continue educating producers and veterinarians. For pork producers, the most valuable actions remain routine wound inspection, prompt reporting of suspicious infestations, understanding movement requirements, and utilizing trusted educational resources before NWS becomes a swine health challenge.
The webinar underscored that protecting the US swine industry will require coordinated action across government, veterinary medicine, extension, and producers—but with preparation and rapid response, NWS eradication remains the goal.
The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit https://www.swinehealth.org or contact Dr. Megan Niederwerder at [email protected] or Dr. Lisa Becton at [email protected].