Cattle screwworm outbreak triggers sanitary measures across Mexico
Mexico is facing a significant outbreak of the cattle screwworm (Cochliomyia hominivorax), a parasite that infects open wounds of livestock and other warm-blooded animals. As of August 2026, the country has reported approximately 1,929 active cases nationally.
In Sonora, authorities have initiated a preventive containment strategy by dispersing 360,000 sterile flies in the Álamos region near the Chihuahua border. This measure aims to create a biological barrier to stop the pest's advancement. In Sinaloa, 22 active cases have been identified across nine municipalities, prompting intensified sanitary inspections and treatments.
Chihuahua has reported a surge in activity with 92 active cases across 25 municipalities, including the detection of suspected cases in the Janos region near the U.S. border. In San Luis Potosí, 80 active cases are being managed, primarily in newborn calves. Aguascalientes has also recorded 24 active cases.
The outbreak has led the United States Department of Agriculture (USDA) to maintain import restrictions on live cattle from affected Mexican states, including Chihuahua, to prevent the parasite's entry into the U.S.
Entities: Chihuahua · Enrique Sánchez Granillo · Government of Sonora · Ismael Bello Esquivel · José Alfredo Sáinz Aispuro · Mexico · Secretaría de Desarrollo Rural · Senasica · Sinaloa · USDA · United States
Claims
What the coverage asserts, and how well corroborated each claim is across sources.
- [● 2 SOURCES] Chihuahua reports 92 active cases across 25 municipalities. (Chihuahua has reported 92 active cases of cattle screwworm.)
- [● 2 SOURCES] The parasite is transmitted by flies laying eggs in open wounds of warm-blooded animals. (The cattle screwworm is caused by the larvae of the fly Cochliomyia hominivorax.)
- [● 2 SOURCES] The first dispersion of sterile flies occurred in Álamos, near the Chihuahua border. (Sonora government is dispersing 360,000 sterile fly larvae to create a containment block against the cattle screwworm.)
- [○ 1 SOURCE] As of August 5, 2026, there were 1,929 active cases recorded nationally in Mexico. (Mexico reported a total of 1,929 active cases of cattle screwworm nationwide.)
- [● 4 SOURCES] Active cases in Sinaloa are distributed in San Ignacio (6), Escuinapa (4), Elota (3), El Rosario (3), Culiacán (2), and one each in Badiraguato, Concordia, Mocorito, and Mazatlán. (Sinaloa reports 22 active cases of cattle screwworm across nine municipalities.)
- [○ 1 SOURCE] San Luis Potosí maintains 80 active cases, primarily in newborn calves. (San Luis Potosí has 80 active cases of cattle screwworm.)
- [● 2 SOURCES] The USDA has suspended cattle imports from certain Mexican states following the detection of the pest. (The United States has maintained restrictions on the import of live cattle from Chihuahua and other Mexican states.)
- [○ 1 SOURCE] Aguascalientes reports 24 active cases, with Rincón de Romos concentrating nine. (Aguascalientes has 24 active cases of cattle screwworm.)