Screwworm Fight in Yucatán May Take 2 More Years

Yucatán, Mexico — The presence of the screwworm in southeastern Mexico may persist for at least another two years before the release of sterile flies begins to significantly reduce the insect population, according to Gustavo Alberto Martín Quijano, permanent advisor of the Biomasa Foundation for Conservation A.C.

Commercial Impact and Sanitary Restrictions

Martín Quijano, a veterinarian, explained that the screwworm infestation is more of a commercial issue than a public health concern, as it is currently concentrated in the southeast due to the region’s favorable climate for fly proliferation.

“The problem affects all livestock producers due to the restrictions imposed by the United States to ensure the quality of imported meat,” he added.

The U.S. government has allocated $50 million to reactivate a sterile fly production plant in Mexico, which ceased operations in 2013. The funds aim to curb the spread of the screwworm, a pest that jeopardizes livestock exports.

Estimated Timeline for Eradication

Martín Quijano projected that even if the plant becomes operational by the end of the year and begins producing sterile flies in 2026, results will not be immediate.

“This isn’t like spraying insecticide and killing them outright,” he emphasized.

The sterile male flies mate with females, preventing further reproduction. While this biological control method is proven, it requires time—likely two years—before a noticeable decline in screwworm cases occurs.

He clarified that the issue is primarily economic, with minimal public health risks. As of May, Mexico’s Ministry of Health had confirmed only six non-fatal cases of myiasis (infestation by fly larvae) in humans.

Livestock Zones Under Surveillance

In Yucatán, most bovine cases have not been reported in Tizimín, the state’s largest cattle-raising area, due to stricter controls. However, in other regions or among small-scale producers, livestock inspections occur weekly, allowing infested wounds to go unnoticed until the infestation becomes severe.

State authorities reported 46 confirmed screwworm cases across 14 municipalities, with infected animals receiving prompt treatment to prevent further spread.

Case in a Stray Dog: "Dingo" in Tetiz

Animal rights activist Alejandra Noh Basto confirmed a screwworm infestation in a stray dog named “Dingo,” rescued in Tetiz, Yucatán. The dog suffered severe wounds with visible larvae, a result of unsanitary conditions.

Sanitary Controls and Border Negotiations

During a press conference, President Claudia Sheinbaum announced that $30 million will be allocated to establish the sterile fly production plant, with a sole global supplier. Installation is expected within 10 to 11 months, though border restrictions on livestock will not lift immediately.

Sheinbaum highlighted ongoing measures, including sanitary checkpoints where veterinarians inspect and clean livestock. She urged against closing the border upon detecting infected animals and called for “clear, technical indicators” to guide decisions.

Agriculture Secretary Julio Berdegué has already met with U.S. counterparts to finalize these terms.