New World Screwworm Returns to the United States: Threats to Animals and Food Supply

In June 2026 a domestic dog in Florida was confirmed to carry New World screwworm (NWS), the first U.S. case since a limited 2017 outbreak in the Florida Keys. Female screwworm flies lay 200–300 eggs on open wounds or mucous membranes; larvae hatch within 12–24 hours, burrow into living tissue, feed for about a week, then drop to the ground to pupate. The parasite can infest livestock, pets, wildlife, and rarely humans, but it does not spread between animals. The Dallas Federal Reserve estimates that a widespread infestation could generate billions of dollars in losses for the southwestern United States.

Deadly flesh-eating parasite poses risk to pets this summer: Here are the safety tips to knowCNN

CDC and USDA officials stress that NWS poses no direct risk to human food safety because the larvae require living tissue and cannot survive on meat. CDC researchers and Texas A&M Veterinary Medicine and Biomedical Sciences scientists advise pet owners to keep wounds clean, cover them, and watch for foul odor or swelling. USDA guidance requires any animal with active larvae to be examined by a veterinarian and to be withheld from the food supply until treatment residues clear under FDA rules. Maximillian Seunik of Screwworm Free Future notes the parasite threatens food prices, while Dr. Jonathan Cammack of Oklahoma State University says a single infested animal does not guarantee herd-wide spread. Veterinarians in Florida report a rise in wound-care inquiries, and hunters in Texas and New Mexico have been told to avoid handling visibly infested wildlife and to contact state Wildlife Services.

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Sources concur that NWS cannot survive on non-living material, yet precise current infestation numbers are not available, leaving a surveillance gap.

Deadly flesh-eating parasite poses risk to pets this summer: Here are the safety tips to know

USDA and CDC will maintain nationwide monitoring, while Texas and New Mexico expand education campaigns for veterinarians, hunters, and livestock producers; stakeholders are urged to report sightings to local wildlife or agricultural authorities.

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• “Meat is still safe,” — Dr. Jonathan Cammack, assistant professor, Oklahoma State University

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• “It’s not even a true disease, like what we think of with a bacteria or a virus that spread from animal to animal.” — Dr. Jonathan Cammack

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• “It’s not even a true disease, like what we think of with a bacteria or a virus that spread from animal to animal. So if a single animal in a herd or pack or group is infested, that doesn’t mean that every other animal in that group is going to be infested.” — Dr. Jonathan Cammack

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• “If a sick animal did end up at a slaughterhouse, the US Department of Agriculture’s thorough meat inspection system would very likely spot it, separate it from others and deem it US Suspect.” — Dr. Jonathan Cammack

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