First animal case of New World screwworm in 10 years discovered in Florida

An animal wound with New World screwworm eggs,
larvae and an adult. (Photo by Samantha Gibbs, FWS)

The first New World screwworm animal case in 10 years was discovered in Florida earlier this week, prompting farm leaders and state officials to acknowledge that, although current protocols prevented this infected animal from entering the U.S., the noxious pest's reentry may be inevitable.

The blowfly larvae rode in on a horse "from Argentina [that] presented for routine inspection at an import quarantine facility in Florida," report Chris Torres and Joshua Baethge of Farm Progress. Larvae samples collected from a wound during the horse's examinations were "shipped to the National Veterinary Services Laboratories in Iowa, and it was confirmed that the larvae were New World screwworm."

Sid Miller, Texas agriculture commissioner, said "the detection is proof of the importance of USDA’s import inspection and quarantine protocols," Torres and Baethge write. According to Miller, "Our federal inspection system is working exactly as designed and is an additional biosecurity tool that will protect our industry."

At the annual Lancaster Cattle Feeders Day in late January, Colin Woodall, the CEO for the National Cattlemen's Beef Association, told fellow cattle producers, "You should be worried about [NWS] because no doubt there will be a market impact." Torres and Baethge add, "Woodall said beef producers should be prepared for an outbreak."

Using millions of sterile male NSW blowfly dispersals, the USDA and Mexican authorities have been trying to get ahead of the pest's travel through Mexico and into the U.S., where it's most likely to cross into Texas. Farm Progress reports, "The USDA also announced a new dispersal area for sterile flies going as far as 50 miles into Texas to stop the insect’s northern spread."

Female screwworm flies most often lay their eggs in the open wounds or scratches of sheep or cattle, but the larvae will feed on the flesh of any warm-blooded animal, which should leave more than cattle producers worried. Torres and Baethge explain, "Miller says screwworms can infest any of the 200 mammal species in Texas. That’s bad news for pet owners, not to mention the state’s multibillion-dollar wildlife industry."