06/06/2026
In early June, USDA APHIS announced the detection of New World Screwworm in a 3-week-old calf in Zavala County, Texas. This was the first detection of NWS in the United States since the 1960s. Additional cases have since been identified in calves, a dog and a goat.
New World screwworm (NWS, Cochliomyia hominivorax) can infest any warm-blooded animal, including livestock, pets, wildlife, occasionally birds, and, rarely, humans. Screwworms are fly larvae (maggots) that burrow into flesh and feed on the living tissue of animals. If not treated, infestation can be fatal.
The Oregon Department of Agriculture is restricting the movement of animals from any area that is actively infested with NWS, and requiring enhanced inspection and preventative treatments prior to entry into Oregon.
While this should not cause excess alarm for Oregon animal owners, it's always a good idea for owners to be aware and watch for signs of any illness in their animals.
Signs of NWS:
* Maggots or white egg masses in wounds or body openings, such as the nose, ears, genitalia, or the navel of newborn animals
* Foul odor or the smell of decay
* Signs of pain including irritated behavior, depression, not eating, and animals isolating themselves from other animals or people
Treat for ticks and keep pets on flea/tick preventives year round to avoid open wounds.
Immediately report any suspicious wounds, maggots, or infestations to your veterinarian or the Oregon State Veterinarian’s office at 503-986-4711.
The US food supply is safe. NWS is not a food safety issue. It spreads only when an NWS fly lays eggs in a wound, not through meat, poultry, or dairy products.
