Florida Agriculture Commissioner Wilton Simpson has extended a temporary moratorium on the importation of warm-blooded animals from parts of Texas and New Mexico after the destructive New World screwworm was detected in both states.
The initial emergency order was issued on June 5, following the confirmation by the U.S. Department of Agriculture (USDA) of the first case in a three-week-old calf in Zavala County, Texas. This marked the first reappearance of the parasite on the U.S. mainland in decades.
By June 8, the USDA confirmed six domestic cases in total: four cattle, one goat, and a dog. Detections spread to La Salle and Gillespie counties in Texas, and a case in a dog was confirmed in Lea County, New Mexico.
Emergency Measures and Infested Zones
The updated emergency rule designates "infested zones" encompassing any county with a confirmed detection and its neighboring counties, prohibiting the importation of rescue and shelter dogs and cats from the affected states until further notice.
All warm-blooded animals from high-risk areas must have a valid Official Veterinary Inspection Certificate, effective for five days, explicitly certifying the animals are free of the parasite's larvae.
Animals coming from a county with confirmed detection or its surrounding counties will also require a state transfer certificate and evidence of preventive treatment.
Current Status and Preventive Actions
To date, there have been no detections of the screwworm in Florida. Simpson has received approval from Governor Ron DeSantis to amend an existing executive order to maximize state resources in response to the threat.
The New World screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals, leading to severe and potentially fatal wounds. Authorities emphasize that the parasite does not affect the food chain: it does not infest meat, fruits, or vegetables.
Historical Context and Recent Developments
The parasite was eradicated from the U.S. mainland in 1966 through the USDA's sterile insect technique program, which involved releasing irradiated sterile males to disrupt reproduction.
The only recent U.S. outbreak occurred in the Florida Keys in 2016-2017, resulting in the death of 135 Key deer and requiring the release of 188 million sterile flies for eradication.
The current reintroduction is tied to the parasite's spread in Mexico since late 2024, with over 5,000 cases reported by August 2025 in states such as Chiapas, Tabasco, Oaxaca, and Veracruz, and a rapid spread northward.
State authorities urge veterinarians, ranchers, and animal shelters to monitor for slow-healing wounds containing larvae. "The New World screwworm remains a constantly evolving situation, and Florida's response will continue to adapt as conditions change," Simpson stated.
"We will remain the most aggressive state in the nation in protecting our livestock, pets, wildlife, people, and agricultural economy from this threat," he emphasized.
Understanding Florida's Response to the Screwworm Threat
What measures has Florida taken to prevent the spread of the screwworm?
Florida has extended a temporary moratorium on importing warm-blooded animals from affected areas, established infested zones, and requires veterinary inspection certificates for animals from high-risk areas.
How was the New World screwworm eradicated in the past?
The screwworm was eradicated from the U.S. mainland in 1966 through a USDA program that released sterile flies to interrupt the parasite's reproduction cycle.
Are there any cases of screwworms in Florida currently?
As of now, there have been no detections of the screwworm in Florida.