Mexico reports 53% surge in screwworm cases

Cases of New World screwworm, a flesh-eating parasite that infests livestock and sometimes humans, have risen sharply in Mexico. According to Mexican government data cited by Reuters, as of August 17 there were 5,086 recorded infestations in animals — a 53 percent increase in just one month, with 649 active cases.

The infestations, which primarily affect cattle, have also been confirmed in dogs, horses, sheep, and humans, reports BBC News. Mexican media noted that dozens of people have been treated in hospitals in the southern states of Campeche and Chiapas, and at least one elderly woman died in July when a screwworm infestation worsened an existing cancer condition.

Mexico has confirmed 41 human cases in the past year, mainly in Chiapas, and that the outbreak has already disrupted the country’s cattle exports, causing losses estimated at $1.3 billion. The U.S. Department of Agriculture warns that if uncontrolled, the parasite could threaten up to $100 billion in livestock-linked economic activity in the United States.

The U.S. Centers for Disease Control and Prevention recently confirmed the first U.S. human case, involving a Maryland patient who had returned from El Salvador. In response, the U.S. Department of Agriculture is sending teams to Mexico to verify control measures and has announced new funding for “sterile fly” production facilities in Chiapas, Texas, and Panama. These facilities aim to release sterilized male flies to curb the parasite’s spread, a method successfully used to eradicate NWS in the U.S. in 1966 and Mexico in 1991.

The USDA’s Animal and Plant Health Inspection Service stresses that prevention and early detection are critical, urging livestock producers to report suspicious wounds and remain alert to signs of infestation such as maggots, decay odor, or unusual animal behavior.

“This is absolutely concerning,” said Neal Wilkins, CEO of the East Foundation, in remarks to Reuters. “A 50 percent increase in a single month shows they haven’t gotten it under control.”