New World Screwworm Outbreak Spreads to New Mexico, Triggers Quarantine Measures
A surge in New World screwworm infestations has prompted quarantine measures in Texas and now New Mexico, according to the U.S. Department of Agriculture (USDA). The parasitic fly, which lays eggs in open wounds of mammals, has been detected in multiple counties in Texas since April 2024, with confirmed cases expanding to New Mexico by June, as reported by the New Mexico Department of Agriculture.
The USDA’s Animal and Plant Health Inspection Service (APHIS) stated that the infestations pose a “significant threat to livestock and wildlife,” requiring immediate containment. Infected animals exhibit severe tissue damage, and untreated cases can lead to death. The agency has deployed monitoring teams to affected regions, while state officials in New Mexico have restricted the movement of livestock from infested areas.
Quarantine Measures and FDA-Approved Treatments
Texas and New Mexico have implemented quarantines targeting cattle, goats, and other susceptible animals. The Texas Animal Health Commission (TAHC) mandates that all livestock in designated zones undergo inspection before being moved. “This is a critical step to prevent further spread,” said TAHC Director Maria Lopez.
The U.S. Food and Drug Administration (FDA) has approved insecticides and larvicides for treating screwworm infestations, including ivermectin and diazinon. According to the FDA, these products “effectively disrupt the life cycle of the parasite when used as directed.” Veterinarians in both states are advising farmers to apply treatments promptly and report suspected cases to local agricultural offices.
Historical Context and Public Health Concerns
New World screwworms were eradicated from the U.S. in the 1980s through a sterile insect technique (SIT) program, but outbreaks have resurfaced in recent years. The 2020 infestation in Arizona and Texas led to the treatment of over 100,000 animals, according to the USDA. Public health officials warn that the flies can also affect humans, particularly those with open wounds, though human cases remain rare.
“This is a reminder of the importance of ongoing surveillance,” said Dr. James Carter, a veterinary entomologist at Texas A&M University. “While the SIT program has been successful, climate changes and wildlife movements could reintroduce the threat.” The USDA is collaborating with Mexican authorities, as the parasite is more prevalent in Central America, to monitor cross-border spread.
What Comes Next?
The USDA has allocated $5 million for eradication efforts, including aerial spraying of insecticides in high-risk zones. New Mexico officials are urging farmers to remain vigilant, with the state’s agriculture department launching a public awareness campaign. “Early detection is key,” said New Mexico Agriculture Secretary Linda Ruiz. “Farmers should inspect their animals daily and report any unusual symptoms.”
As the infestation continues to evolve, experts emphasize the need for coordinated state and federal action. The FDA and USDA are also reviewing updated treatment protocols to address potential resistance in screwworm populations.