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Baja California’s Agriculture Secretariat completed a training exercise designed to sharpen the state’s ability to detect and respond to an outbreak of New World screwworm, a parasitic fly that has not been found in the state but is advancing northward through Mexico at an alarming pace.
The seminar, called Auto Sim II, brought together animal health inspectors, officials from SENASICA (Mexico’s food safety and agriculture agency) and ISESALUD (the state health institute), ranching associations, veterinarians, and commercial feedlot operators. Participants ran a live simulation at a livestock production unit and conducted outreach visits to farms and residences across the state.
A Pest That Has Reached the U.S. Border
New World screwworm (Cochliomyia hominivorax) is a fly whose larvae burrow into the open wounds of living, warm-blooded animals. Infestations are painful and often fatal without treatment. The pest can affect cattle, horses, dogs, wildlife, and in rare cases, humans.
The fly was eradicated from the United States and northern Mexico decades ago through sterile-insect programs. But it re-emerged in Central America and has spread rapidly. Mexico has reported more than 29,300 cases since November 2024, with roughly 1,960 active cases as of mid-June 2026. At least 12 confirmed cases have appeared in U.S. livestock since June 3, according to USDA data.
Baja California, along with Baja California Sur, Chihuahua, Sinaloa, and Sonora, currently has zero confirmed screwworm cases. SENASICA has said its prevention measures are specifically intended to keep those northwestern states free of the pest. Mexico also suspended most livestock imports from the United States in June to prevent cross-border spread.
What the Drill Covered
Specialists from the CPA, the joint Mexico-U.S. Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Animal Diseases, led the exercise. The drill also updated the membership of Baja California’s State Animal Health Emergency Group, known as GEESA, which coordinates the state’s response to animal disease emergencies.
Outreach visits to ranches and residences are ongoing. Livestock trade through U.S. ports of entry along the southern border is currently closed because of screwworm in Mexico, according to USDA’s Animal and Plant Health Inspection Service. Anyone who keeps horses, cattle, goats, or other livestock in Baja California should watch for signs of wound infestations and report suspicious cases to local animal health authorities.
This story was first reported by La Jornada Baja California.