Resources with keywords: new world screwworm
As of February 17, 2026, Central America and Mexico have reported more than 153,000 NWS cases in animals and over 1,300 cases in people.
CDC is issuing this Health Alert Network (HAN) Health Advisory to share information and notify clinicians, public health authorities, and the public about recent New World screwworm (NWS) animal cases in the Mexican state of Tamaulipas, which shares a border with the U.S. state of Texas.
The U.S. has confirmed its first human case of the New World screwworm, a flesh-eating parasite whose northward creep from South America has put the country’s cattle industry on high alert in recent months.
New World screwworm (NWS) infestation occurs when NWS fly larvae (Cochliomyia hominivorax) infest the tissue or flesh of warm-blooded animals. In places where the flies are present, people can also become infested.
To ensure the protection of U.S. livestock herds, USDA is holding Mexico accountable by ensuring proactive measures are being taken to maintain a NWS free barrier. This is maintained with stringent animal movement controls, surveillance, trapping, and following the proven science to push the NWS barrier south in phases as quickly as possible.
APHIS Experts Evaluated Mexican Response to New World Screwworm and Found Trade Can Begin
