Mexico's screw-worm fly spreads to 28 states, triggers health and livestock alerts

Mexico's screw-worm fly (Cochliomyia hominivorax) has been confirmed in 28 of the country's 32 states, with nearly 2,000 active cases. The infestation has caused an estimated $400‑500 million in losses and prompted the temporary closure of the border for live‑cattle exports, especially from northern states such as Chihuahua.

Human cases have also risen, beginning with the first reported infestation in a Puerto Vallarta resident and later cases in Veracruz (70 confirmed) and other regions. A study by the National Institute of Public Health and Cinvestav warned that climate change will expand high‑risk zones, notably in Yucatán, Campeche, Quintana Roo, Chiapas and Tabasco.

Authorities are scaling up containment measures: ranchers receive training on wound hygiene, farms increase fumigation with cipermetrina, and a sterile‑fly release program is being expanded from a plant in Metapa, Mexico, to a larger facility in the United States. Juan Carlos Anaya of the Grupo Consultor de Mercados Agrícolas emphasized that “already there are positive cases in 28 states and also in Texas (38) and New Mexico (1), so coordination with the U.S. is essential.”