Health officials confirmed the first New World screwworm (Cochliomyia hominivorax) travel-associated human infection in the United States in decades on August 25, 2025. The discovery serves as a sobering reminder of how easily eradicated parasites can resurface and endanger the health of both people and animals.
Case Details
The patient, who resides in Maryland, just got back from a trip to Central America. They were diagnosed with a screwworm infestation shortly after they started exhibiting strange symptoms. In early August, following the collection and analysis of larvae, laboratory confirmation was made.
Although the patient is undergoing treatment and should recover, the incident highlights how dangerous parasites can be reintroduced into areas where they have been eradicated for a long time, according to health authorities.
Understanding the Screwworm
A parasitic fly species known as the New World screwworm deposits its eggs in the open wounds of warm-blooded creatures, including people. After hatching, the larvae burrow into living tissue, where they feed voraciously and inflict excruciating wounds. Infestations can be lethal if untreated.
In the 1960s, a massive eradication effort eradicated this parasite, which had previously been widespread throughout the southern United States. In order to disrupt reproduction cycles, that endeavor depended on releasing male flies that had been sterilized; this method proved to be a groundbreaking success in pest control.
Screwworms are still active in some regions of Central and South America even though they have been eradicated in the United States. The parasite has been able to spread northward since late 2024 due to a sharp increase in livestock cases throughout the region.
Hazards to Agriculture and Health
Experts emphasize that there is very little chance of widespread human infection in the United States. In regions where the screwworm is endemic, human infestations are uncommon and usually associated with travel. Typically, treatment consists of cleaning the tissue and extracting the larvae from the wound, then administering antibiotics if necessary.
Livestock is the bigger issue. Devastating losses can result from screwworm infestations in cattle and other animals. According to economic models, the annual damage from a reintroduction of screwworms in the United States could amount to billions of dollars, especially in states that produce cattle. Large-scale treatment efforts, decreased productivity, and livestock deaths would all be expenses.
Emergency Measures
U.S. authorities have already started to strengthen preventive measures in response to the new case. In South Texas, a facility for producing sterile male screwworms in large quantities is currently under construction. Officials hope that by releasing these flies into the environment, any wild populations will be unable to reproduce successfully, repeating the success of previous eradication efforts.
Additionally, some veterinary medications have received emergency approvals from federal agencies to assist farmers in treating or preventing animal infestations of screwworms. Additionally, to lessen the possibility of the parasite entering through cross-border movement, import restrictions on livestock from high-risk areas have been strengthened.
Looking Ahead
Despite previous successes, global health threats can reappear, as evidenced by the confirmation of the first human screwworm case in decades in the United States. Eradication is not always a guarantee of long-term safety in the connected world of today.
Authorities are treating the incident as a warning, even though the individual case is under control and there is still little risk to the public’s health. Protecting human and animal populations will require constant attention, prevention funding, and cooperation between the agriculture and health sectors.