USDA Confirms New World Screwworm Cases in Texas and New Mexico After 60-Year Absence

The U.S. Department of Agriculture confirmed on June 3 that the New World screwworm, a flesh-eating parasite, had returned to the United States after an absence of roughly 60 years. Within three weeks, 15 cases in livestock and pets were recorded across Texas and southeastern New Mexico.

Tyler Hoard, an associate physical scientist at the RAND Corporation, wrote that the outbreak should be treated as a broader warning for crop biosecurity. Hoard and co-authors published research this spring that examined U.S. preparedness for crop diseases.

Hoard noted that the Corn Belt produces more than one-third of U.S. corn and 34 percent of the world's soybeans, with combined export value exceeding $34 billion. He said modern practices of planting large acreages to a narrow set of high-yield varieties increase vulnerability.

Historical examples cited by Hoard include a 1970s Southern corn leaf blight outbreak that destroyed 15 percent of the North American corn crop and two deliberate contamination incidents: cyanide-laced Chilean grapes in 1989 that cost Chile's agriculture sector $330 million and mercury-injected Israeli oranges in 1978 that cut European imports from Israel by 40 percent.

Hoard stated that the United States lacks an equivalent to the screwworm containment playbook for crops. He called for expanded pathogen surveillance modeled on CDC wastewater monitoring, rapid field diagnostics for county agents, biosecurity standards at large crop operations, a rapid-response research fund, and forensic capabilities to distinguish natural from deliberate outbreaks.

Hoard argued that the cost of such measures would be small compared with potential losses from a single successful introduction of a novel pathogen into the Corn Belt.