Officials confirm flesh-eating New World screwworm parasite found in US wildlife

The United States Department of Agriculture (USDA) has confirmed the first instance of the flesh-eating New World screwworm in wildlife in Texas and a beef cow in New Mexico, as reported on October 21, 2022. The source of this parasitic outbreak appears to be spreading from Central America through Mexico.

An elk found on a game ranch in Pecos County, Texas, tested positive for the screwworm after being harvested by a hunter. In response, the Texas Animal Health Commission is expanding an infested zone, and USDA and Texas Parks and Wildlife Department are conducting further surveillance in the area.

Separately, the New Mexico Department of Agriculture announced the discovery of a New World screwworm in a beef cow in Otero County. State and federal officials in New Mexico are intensifying surveillance and fly-trapping efforts to detect additional cases and evaluate if the pest has expanded beyond the affected animals.

To prevent further transmission, a 12.4-mile (20 km) infested zone has been established around the location of the infected cow in New Mexico. Within this zone, animals must undergo inspections and, if required, be treated before moving within or out of the area.

The screwworm, which was eradicated from the US decades ago, has recently reappeared northward from Central America via Mexico. In an effort to curb the pest's spread, the US imposed a ban on Mexican cattle imports that lasted over a year. However, this trade restriction was temporarily lifted in August as part of a phased reopening plan to address the impact on US cattle supplies.