According to the U.S. Department of Agriculture, the flesh-eating New World meatworm was recently discovered in Mexico, just 25 miles from the U.S. border. Federal records indicate this was the closest detection of this parasite to U.S. soil since at least September of last year.
On Thursday, a five-year-old goat was found infected with a blowfly in the Mexican state of Coahuila, which borders southwest Texas. According to the U.S. Department of Agriculture, U.S. authorities have tracked 32 cases of the parasitic bug in the state, including 19 active cases.
In total, according to the USDA, at least 26,216 cases of screwworm infestations have been identified in Mexico, with more than 2,700 of them remaining active. The agency posts twice-weekly updates on new cases detected within 400 miles of the United States in Mexico, and on its New World screwworm webpage, it specifically notes that the pest is "currently absent" from the United States and that "the current risk to livestock, other animals, and people in the United States remains very low.".
However, in recent months and years, this parasite has begun appearing closer to the United States than ever before. In April, Texas Agriculture Commissioner Sid Miller announced that it had been detected in Mexico, 60 miles from the U.S. border, as CBS Texas reported at the time. Texas authorities had been warning outdoor enthusiasts about this parasite since late 2024, when the state Parks and Wildlife Department issued an alert about a blowfly recently found on a cow in southern Mexico.
Last year, the first human case of fly larvae infection was confirmed in the United States, the Department of Health and Human Services reported at the time. The case was detected in a traveler returning to Maryland from El Salvador, Department of Health and Human Services spokesman Andrew Nixon said in a statement to CBS News. Maryland health officials later reported that the person had recovered, and investigators found no evidence of transmission to other people or animals.
The New World screwworm is a parasitic fly that feeds on warm-blooded animals and humans. It lays eggs in open wounds or orifices, such as the eyes, ears, nose, or mouth. After hatching, the larvae can feed on living tissue or flesh, according to the Centers for Disease Control and Prevention (CDC). The parasitic fly is typically found in South America and parts of the Caribbean, but over the past three years, it has been detected further north, in Central America and Mexico, according to the CDC.