More than 500 people in Mexico have contracted screwworm myiasis between 2025 and 2026, according to a surveillance report from the Secretaría de Salud cited on August 7 by Ars Technica. The figure turns the outbreak, which re-emerged in the country in 2024 after decades of eradication, into a binational public health concern.
The New World screwworm (Cochliomyia hominivorax) deposits hundreds of eggs in wounds and mucous membranes of animals and people, and its larvae feed on living tissue. Mexico had declared the species eradicated in 2003, but the biological barrier of the Darién Gap, which had kept Panama free since 2006, broke in 2022 and the outbreak reached Mexican livestock in 2024. The U.S. Centers for Disease Control and Prevention (CDC) report, with figures through July 31, more than 189,000 cases in animals and 2,360 in people across Mexico and Central America, and maintain active surveillance over the movement of travelers and livestock at the border.
A study published this week in the journal Emerging Infectious Diseases analyzed 202 confirmed cases between April 2025 and March 2026 and found that the pace of transmission accelerated: from roughly three cases per week in 2025 to more than nine per week in 2026. The study documents six deaths, at least one directly caused by the larvae. In livestock, the U.S. Department of Agriculture counts more than 36,000 cases in Mexico, with approximately 2,000 active as of August 5. On U.S. territory, the CDC confirmed in August 2025 a human case associated with travel to El Salvador; there are no domestically acquired human infestations in the country, and the first animal case was detected on June 3, 2026.
The Secretaría de Salud publishes its weekly registry and the cumulative figure continues to climb, according to official data. The study's authors call for strengthening surveillance at the northern edge of the fly's advance, which is already being detected near the U.S. border, and the CDC updates its situation report weekly.
This article was drafted with artificial intelligence assistance based on verified sources and reviewed by a human editor before publication.