What it is
The New World screwworm is a parasitic insect that lays eggs in open wounds of warm-blooded animals. Once hatched, the larvae feed on living tissue, causing a dangerous condition known as myiasis that can devastate both humans and livestock. Once endemic to the southern U.S., screwworms were declared eradicated in the 1960s thanks to sterile fly release programs. The parasite, however, still persists in parts of Latin America. Its reappearance in American headlines raises alarm not only for individual health cases but also for its potential to disrupt agriculture and impose heavy economic costs on cattle, horses, and other livestock industries.
Why it’s trending
In late August 2025, U.S. health officials confirmed the first human screwworm case in decades, detected in Maryland after a patient returned from El Salvador. The announcement triggered swift action by federal and state agencies, with the USDA unveiling a $750 million program to mass-produce sterile flies in Texas, capable of releasing 300 million insects per week. This aggressive response mirrors successful eradication methods of the past, but its cost and urgency underscore the seriousness of the threat. Public health experts warn that increased global travel and climate shifts may create new conditions for screwworms to reappear, heightening public concern.