New World Screwworm Detected South of Texas

According to Mexico's health ministry's latest epidemiological bulletin, an older woman recently died from New World Screwworm (NWS) in the city of Candelaria in Campeche state.

This disease is spread by the fly Cochliomyia hominivora, which deposits larvae that burrow into the flesh of livestock, wildlife, pets, and sometimes people, causing severe damage.

The health ministry has reported 35 human cases of NWS in 2025, mainly from Chiapas state.

Mexico and partners in the United States have been battling a recent northward spread of the fly through Central America.

The US Department of Agriculture writes that in 2023, NWS detections in Panama increased from an average of 25 cases per year to more than 6,500 cases in one year.

Since then, NWS has been detected in Costa Rica, Nicaragua, Honduras, Guatemala, Belize, El Salvador, and Mexico, north of the biological barrier that has successfully contained this pest to South America for decades.

On July 9, 2025, Mexico's National Service of Agro-Alimentary Health, Safety, and Quality reported a new case of NWS in Ixhuatlan de Madero, Veracruz, Mexico, which is approximately 370 miles south of the US/Texas - Mexico border.

“The United States has promised to be vigilant, and after detecting this new NWS case, we are pausing the planned port reopenings to quarantine further and target this deadly pest in Mexico. We must see additional progress in combating NWS in Veracruz and other nearby Mexican states to reopen livestock ports along the Southern border," commented US Secretary of Agriculture Brooke L. Rollins, in a press release.

As of August 6, 2024, there are no NWS vaccines available.