Mexico has recorded more than 500 human cases of New World screwworm infestation since the parasite reappeared in the country, according to health surveillance data. The growing number of infections matters because the fly’s larvae feed on living tissue, can cause severe wounds and infections, and pose a major threat to both people and livestock.

A study of 202 confirmed cases from April 2025 to March 2026 found the reporting rate rose from about three cases a week in 2025 to more than nine a week in 2026. Seventy-two per cent of patients were male, the average age was 61, and 77 per cent had underlying conditions such as diabetes, alcoholism, cancer or skin disease; six deaths were reported, although only one was directly attributed to screwworm infestation. Mexico had eradicated the pest in 2003, but it returned after a containment barrier in Panama was breached in 2022, with more than 36,000 animal cases now reported in Mexico.