First case of human infection with the screwworm parasite in the USA

• The first case of human infection with the screwworm parasite in the USA was recorded on August 4.
• The parasite poses a risk only to livestock, not to humans.
• The U.S. government is taking measures to prevent the further spread of the parasite.

On August 25, 2025, the U.S. Department of Health and Human Services reported the first case of human infection with the New World screwworm, which is associated with travel to regions where the pest is endemic. As of August 4, the Centers for Disease Control and Prevention (CDC) confirmed that the patient had returned from El Salvador.

Earlier, it was reported that a case was also registered in Maryland involving a person who traveled from Guatemala. However, a representative from HHS did not comment on discrepancies in the information provided. According to him, the risk to public health in the USA is very low.

The U.S. government has not confirmed any other cases of livestock infection this year, but the livestock industry is already at a high level of readiness due to the potential for infection. According to estimates, the screwworm infestation could cause economic losses in Texas, the largest cattle-producing state in the USA, amounting to approximately $1.8 billion.

The CDC is collaborating with the U.S. Department of Agriculture to prevent the further spread of the parasite, which was previously a serious problem for the American cattle industry until its near eradication in the 1970s.

Screwworms lay their eggs in the wounds of warm-blooded animals, and their larvae can cause severe damage if not treated promptly. Treatment is complex but possible if started in the early stages.

Tags: USA