Flesh-eating New World Screwworm infestations have spread to Arizona, becoming the third US state affected this season alongside New Mexico and Texas. The parasitic larvae, which re-entered the country in June after a 2022 biological barrier breach in Central America, have prompted dozens of documented animal cases.
The southern border has become the frontline for a biological threat not seen in decades. Ravaging maggots of the New World Screwworm have pushed past previous geographic boundaries, reaching Arizona this week and adding it to an active containment zone that already includes New Mexico and Texas.
US Animal Cases Reach 74 Since June Re-Invasion
Federal agriculture officials have tracked a steady accumulation of infections since the parasitic flies crossed back into the United States earlier this year.
The lifecycle of the insect presents an aggressive threat to mammals. Adult female flies deposit hundreds of eggs directly into open wounds or moist bodily orifices. Once hatched, the voracious larvae use screw-like body structures to bore into living tissue, creating severe and potentially fatal wounds before dropping to the soil to mature into adult flies.
Pets and Livestock Face Direct Parasitic Threat
While historical eradication efforts focused heavily on safeguarding the agricultural economy, current infestations are directly impacting domestic animals. Recent incidents in the infection zones have involved attacks on household pets.
Historically, the United States successfully eliminated the screwworm population in the 1960s. That eradication relied on widespread aerial releases of sterile male flies to disrupt breeding cycles. For decades, a biological barrier maintained along the Darién Gap between Panama and Colombia kept the pests contained. However, that defense line broke down in 2022, allowing the flies to migrate northward through Central America.
Human Infestations and Toll Recorded in Mexico
The parasites pose hazards beyond livestock and domestic animals, occasionally threatening wildlife and humans. Data published by Mexico’s Ministry of Health documents 806 confirmed human screwworm infestations since the species re-emerged in the region, resulting in nine deaths.