The Oregon Department of Agriculture (ODA) has issued a notice to animal owners, livestock producers, and veterinarians in the state regarding the New World Screwworm (NWS), a parasitic fly that poses a risk to animals and, in rare cases, humans. While NWS is not currently present in the United States, ODA urges vigilance, especially for those traveling or receiving animals from regions where the pest is found.
New World Screwworm lays its eggs in open wounds or body openings of warm-blooded animals such as livestock, pets, wildlife, birds, and occasionally people. When the eggs hatch, larvae burrow into living tissue and feed on it. This can cause severe infections known as myiasis and may be fatal if untreated.
According to ODA, “New World screwworm is not currently found in the United States, but we are asking animal owners and veterinarians to be on the lookout for possible NWS infestations in animals—especially when traveling or receiving animals from.” The department notes that NWS is mainly located in Central and South America and some Caribbean islands. The pest was eradicated from the U.S. decades ago; however, travelers can inadvertently reintroduce it. In 2024 NWS was detected in Mexico and most recently identified by USDA authorities on September 21, 2025 in Nuevo León state near the U.S.-Mexico border.
ODA advises animal owners and veterinarians to monitor for symptoms including irritated or depressed behavior, loss of appetite, head shaking, foul odor resembling decaying flesh, visible maggots in wounds, or isolation from other animals or people.
Anyone suspecting an infestation should report immediately to their local veterinarian or contact the Oregon State Veterinarian’s office at 503-986-4711. Veterinarians will assist with identification and treatment of suspected cases.
Preventive measures include monitoring pets and livestock for signs of infection. Travelers returning with animals from areas where NWS is present should ensure both animals and vehicles are inspected before entering the United States.
For further information about New World Screwworms or related guidance for Oregon residents involved with animal care or agriculture activities during travel abroad or importation processes can refer to official communications from ODA.
