The Indiana State Board of Animal Health issued an animal movement advisory for New World screwworm after the U.S. Department of Agriculture reported the New World screwworm in New Mexico and Texas.
“While not currently found in Indiana, the insect pest could be carried into the state via people or animals that have visited an infested area or country,” according to the June 9 advisory. “The latest findings have triggered movement restrictions for animals traveling to Indiana from NWS-infested areas, currently in Texas and New Mexico.”
New World screwworms are parasitic flies whose larvae can infest wounds and feed on the tissues of animals and, in rare cases, humans, said Porter County Health Department administrator Matthew Paul.
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New World screwworms flies have orange eyes, a metallic blue or green body, and three dark stripes along their backs. Attracted to the smell, the flies will lay eggs in open wounds on warm-blooded animals, and within hours the eggs hatch as the worms burrow in a screw-like pattern into the flesh to feed, according to the advisory.
“At this time, New World screwworm is not a public health threat in Lake County, but it is an issue to monitor closely because of its potential impact on livestock, pets, wildlife, and, in rare cases, humans,” according to a press release from the Lake County Health Department.
Under the advisory, animal movement restrictions are in effect for all livestock and companion animals coming from an infested zone.
Any animals that leave an infested zone must have an animal movement certificate, inspected by a USDA-accredited veterinarian and obtain a certificate of veterinary inspection issued within 5 days of movement to Indiana, and require a certificate of veterinary inspection documenting application of an effective treatment for New World screwworm applied within 14 days of movement for livestock and poultry and within 5 days of movement for cats and dogs, according to the advisory.
The exceptions to the advisory are hatching and table eggs as well as chicks, poults, or ducklings younger than 5 days, small mammals, exotic birds, swine from indoor-housed commercial swine farms, among others, according to the advisory.
Animal owners of pets, livestock and poultry should watch for the presence of unusual flies or maggots in or around open wounds, sores or body openings; wounds that continue to drain or grow bigger with a smell of decay; and animals showing discomfort, including head shaking or irritated behavior, according to the advisory. If untreated, it can lead to rapid health decline and potentially death, according to Texas A&M University.
Screwworms were largely eradicated from the U.S. in the late 1960s thorough the production of sterile male flies. Since female flies only mate once, they produce no eggs after mating with a sterile male flies. The USDA has been dropping sterile flies in south Texas since February and is working to both increase sterile fly production in plants outside the U.S. and build a $750 million fly factory in Texas, according to the Associated Press.
Currently, the Indiana State Board of Animal Health hasn’t changed exhibition requirements for fairs or open shows, but all out-of-state entries have to meet the advisory’s requirements.
The Porter County Fair each year works to follow the guidance issued by the Board of Animal Health and Purdue, said fair volunteer Andrew Lucas.
“Our 4-Hers go through animal health and quality training. We are ready to follow any guidance handed down from these partners,” Lucas said. “We are ready to follow any guidance handed down from these partners.”
Purdue University Extension educators that specialize with animals and livestock have regular meetings about any advisories and write articles about the topic, said Rebecca Koetz, a regional agricultural natural resource educator with the Purdue University Extension in Lake County.
For example, when the avian flu epidemic hit a few years ago, Koetz said Purdue University Extension educators would issue updates on the epidemic with guidance, including keeping ducks and chickens separated.
“But with the screwworms, we’re not there yet since it’s not in Indiana,” Koetz said.
Rural communities with livestock, farms, and outdoor animals are at greater risk if New World screwworm were detected in the region. Farmers, veterinarians and pet owners should routinely check animals for wounds and signs of infection, according to the Lake County Health Department press release.
Residents should keep cuts and wounds clean and covered, and seek medical attention if wounds become infected or fail to heal. Pet owners should make sure their pets receive routine veterinary care and livestock and outdoor animals should be regularly checked for wounds or unusual infestations, according to the Lake County Health Department press release.
“The best protection is awareness. Good wound care, routine veterinary care, and early reporting of unusual animal infections can help prevent serious impacts if screwworms are identified in our region,” said Lake County Health Officer Chandana Vavilala in the press release.
If a pet or livestock animal may have New World screwworm infestation, then the owner should seek veterinary care immediately, Paul said. The veterinarian should report suspected cases to the Indiana State Board of Animal Health and the Indiana Department of Natural Resources, he said.
If a resident suspects he or she may have a New World screwworm infestation, medical attention should be sought, Paul said. In August 2025, the United States reported its first human screwworm case in decades after Maryland resident, who had recently traveled to El Salvador, returned with larvae embedded in living tissue, according to Reuters. The infection was treated successfully.
Healthcare providers should contact the Indiana Department of Health, which would give instructions for submitting larvae or eggs for testing, he said.
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