New World screwworm outbreak spreads across Mexico and the United States

The United States Department of Agriculture confirmed a second New World screwworm case in Zavala County, Texas, and later reported three additional incidents, including a terner in La Salle County, Texas, a goat in Gillespie County, Texas, and a dog in Lea County, New Mexico. The pest, a larval stage of a fly that infests open wounds on livestock, poses a threat to the cattle industry.

In Mexico, the national agricultural agency Senasica recorded more than 2,000 active screwworm cases as of 3 June 2026, affecting cattle, dogs, pigs and horses in 26 states. Puebla, Veracruz and Oaxaca report the highest numbers. Mexican authorities have intensified aerial releases of sterile male flies to curb the spread, while maintaining normal meat trade with the United States.