A screwworm case in Mexico near the U.S. border has triggered heightened monitoring, with no spread to the U.S. yet.

A New World screwworm case has been confirmed in Tamaulipas, Mexico, near the U.S. border, marking the first detection in a border state. The parasite, which infests wounds in livestock, has not spread to the United States as of January 2, 2026. Mexican and U.S. officials are monitoring the situation closely, with California’s dairy industry, worth $8.61 billion annually, considered especially vulnerable. The U.S. maintains a cattle import ban along the border and continues its sterile fly program to prevent reinfestation. The FDA recently approved new treatments for screwworm in dogs and cattle.