ODA Establishes Rules To Stave Off NWS

Following the confirmation of New World Screwworm in Texas and New Mexico Oregon’s Department of Agriculture rolled out new rules intended to pro protect animals from a parasitic fly.

"New World Screwworm doesn’t discriminate," said Oregon State Veterinarian Dr. Ryan Scholz. "Any warm-blooded animal, including humans, are at risk. It’s a fly larva. The flies lay their eggs in wounds."

Scholz says NWS is not in the state. In an effort to keep it out, ODA now requires extra testing and paperwork for animals transported from an infested area. If New World Screwworm does make it to Oregon, Scholz said the state has a response plan.

"It’s not a traditional infectious disease, it’s contagious infestation," Scholz noted. "And so we treat it differently. It is very treatable, it just has to be treated quickly and correctly."

Scholz said animal owners should seek immediate attention if pets or livestock have foul smelling or severe wounds that don’t heal appropriately.

History of New World Screwworm

New World Screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae infest the living tissues of warm-blooded animals. Unlike other maggots that feed on dead tissue, the larvae of the New World Screwworm burrow into healthy tissue, causing painful, expanding wounds known as myiasis. These maggots can be found deep within wounds and contribute to their significant expansion in size.

New World Screwworm were first eradicated from the United States in 1966. However, there was a small outbreak in the Florida Keys that was successfully eliminated in 2017. NWS is commonly found in Cuba, Haiti, the Dominican Republic, and several countries in South America.

In recent years, the disease has migrated northward through Central America and is now situated approximately 62 miles south of the border between Mexico and the United States. The United States Department of Agriculture (USDA) is leading a national, One Health response to prevent NWS from entering the United States.

Impacts Of NWS On Companion Animals and Livestock

NWS can infest minor wounds or body openings, such as the mouth, ears, or nose, leading to severe discomfort, enlarged lesions, and infection. Animal owners should closely monitor any wounds, particularly after traveling from affected areas, and promptly report any suspected infestations to your local veterinarian or the Oregon Department of Agriculture.

NWS flies can lay hundreds of eggs in wounds, and the larvae feed, causing extensive tissue damage by burrowing deeper into the tissue over time. This process results in a smell of decay, reduced appetite, decreased production in livestock, and in severe cases, death may occur within 1-2 weeks if left untreated.

Prevention and Early Detection

While NWS is not currently found in the United States, animal owners should routinely maintain appropriate wound management, monitoring and/or treating open wounds and surgical sites. Talk to your veterinarian on the best protocol for caring for any wounds your animal may have.

If traveling or importing animals from areas where NWS may exist, have them inspected by a veterinarian prior to moving those animals. Visit ODA's Website to learn more about moving animals (companion animals & livestock) into Oregon.

What to Do if you Suspect New World Screwworm?

If you suspect New World Screwworm in any animal, contact your local veterinarian immediately for wound examination, larvae removal, and follow-up treatment. You may also call the ODA Disease Reporting Hotline at (503) 986-4711. ODA has additional veterinarian-specific resources available regarding NWS identification, reporting signs, treatment, and prevention, and what to expect.

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