First U.S. human screwworm case confirmed in Maryland, sparking livestock market concerns | investingLive

The first U.S. human case of New World screwworm has been confirmed in Maryland, linked to a traveler from Guatemala. The rare but dangerous parasite threatens cattle herds and could rattle beef markets, with U.S. officials under pressure for slow containment efforts.

Info via Reuters

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The first U.S. case of New World screwworm in a human has been confirmed in Maryland, in a person who recently traveled from Guatemala, according to multiple sources. The infection marks the parasite’s first appearance in the U.S. since an outbreak began spreading north from Central America in 2023.

The discovery has raised alarm among veterinarians and the cattle industry, given the parasite’s potential to devastate livestock. Screwworms are parasitic flies that lay eggs in open wounds, with larvae burrowing into living flesh. In animals, infestations can be fatal if untreated; human cases are rare but possible.

Industry sources said the CDC confirmed the Maryland case privately, but communication was slow, fueling criticism that the USDA and health authorities weren’t transparent enough. The case comes just after U.S. Agriculture Secretary Brooke Rollins announced plans for a sterile fly facility in Texas, though critics argue efforts to stop the pest’s spread have lagged.

The news could unsettle beef and cattle futures markets, already at record highs with the smallest herd size in 70 years. A major outbreak in Texas alone could cost an estimated $1.8 billion. Mexico, facing its own cases, has started building a $51 million sterile fly plant in addition to existing efforts in Panama.