New World Screwworm Alert in Mexico: Rising Cases in Pets and Livestock

New World Screwworm – Mexico: Confirmed Cases in Pigs, Dogs, and Cats

Public Health Updates
January 03, 2026

A health alert has been issued in Mexico following the continued spread of New World screwworm, a parasitic infestation causing myiasis in animals. The disease affects livestock and household pets, particularly dogs and cats, posing a serious threat to animal health and the economy if not promptly treated.

More than 13 months after the re-emergence of screwworm in the country, health authorities have confirmed a growing number of cases in pets in addition to livestock. Official data indicate 1,602 cumulative cases in dogs, accounting for 12.9% of all reported infections nationwide, with 164 cases currently active. In cats, 32 cumulative cases have been reported, with 6 active infections.

Screwworm disease is caused by fly larvae that infest open wounds, where they feed on living tissue, leading to severe injuries and potentially fatal outcomes if untreated. Animals with untreated wounds, poor hygiene, or prolonged exposure to the outdoors are at a higher risk.

Authorities strongly advise immediate veterinary attention for any animal wounds, stressing that early detection and timely treatment are critical to preventing severe complications. While the highest concentration of cases remains in southern and southeastern Mexico, continued surveillance is essential to prevent further spread.