Top Questions on New World Screwworm: What Every Veterinarian Should Know

New World screwworm (Cochliomyia hominivorax) has re-emerged as a serious Veterinary threat, with cases increasing in Mexico and detections reported within about 70 miles of the US border. The parasite causes aggressive primary myiasis, producing foul-smelling, rapidly expanding wounds containing larvae that feed on living tissue and may invade mucosal sites. Veterinarians are urged to suspect screwworm when wounds worsen quickly and larvae are visible head-down.

Suspected cases must be reported immediately to state animal health officials and USDA APHIS, with larvae preserved in 70% ethanol for laboratory identification. Treatment centers on prompt mechanical removal, wound debridement, and supportive care, with FDA emergency use authorizations now allowing lotilaner for dogs and cats. Prevention focuses on vigilant wound care, fly control, and routine parasite prevention. Clinics are advised to update protocols, train staff, and prepare for reporting and isolation. Human infestation is rare but possible, requiring One Health coordination.