The United States has spent decades treating New World screwworm as an eradication success story. That makes the latest case particularly uncomfortable: a working ranch horse in Presidio County, Texas, has become the first confirmed U.S. horse infected in the current outbreak, according to USDA↗ data.
The parasite is the larval form of a fly. Unlike many maggots that consume dead tissue, New World screwworm larvae feed on living tissue inside open wounds. Untreated infestations can enlarge rapidly, cause severe injury and kill livestock or wildlife.
Texas animal-health officials have restricted the movement of warm-blooded animals out of a designated infested area spanning parts of Presidio and Jeff Davis counties. Horse owners are being urged to inspect animals closely, control flies and treat wounds promptly.
The economic reason for the aggressive response is straightforward. Texas is the center of the U.S. cattle industry, and specialists have estimated that a widespread outbreak could generate as much as $1.8 billion in economic damage. Containment depends on sterile-fly programs, surveillance and tight control over animal movement.
For people outside agriculture, this is a reminder that biosecurity is not only about human epidemics. Animal disease can alter food prices, interstate commerce and trade remarkably quickly. A single case does not mean a nationwide outbreak, but it is exactly the sort of threshold event worth watching.
USDA data confirmed New World screwworm in a working ranch horse in Presidio County, Texas. Authorities restricted movement of warm-blooded animals from designated areas as they try to contain a parasite the U.S. eradicated in the 1960s.