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Livestock producers are warned to watch for a larval disease

A disease that lives off the flesh of living mammals has been confirmed in Chiapas, Mexico.

New World screwworm (NWS) is a parasitic larval disease of warm-blooded animals where the female fly will lay eggs near an open wound and the larvae can infest the wound and cause significant infections.

NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people.

Swine Health Information Center (SHIC) Associate Director Dr. Lisa Becton said the confirmation comes on the heels of a report in October from Guatemala where the first case was identified.

“This larva and the fly were identified at the Mexican border in cattle that were coming through in Guatemala and so this is a very significant concern of especially grazing animals but really of any warm-blooded animal,” she said. “It does cause destruction when a wound gets infected.”

Animals can exhibit very painful draining wounds that don’t heal. It has a negative impact on production and can include mortality of animals that are infected.

Becton said the disease has not been identified in the United States.

“It has been found in Mexico at the southern borders however it is something that all producers, swine producers and cattle and beef producers should be aware of because the fly larvae can infest any warm-blooded animal. It is also something to watch for, especially in animals that are reared outdoors or have outdoor access because the flies can land and cause problems,” Becton said.

The United States Department of Agriculture is involved and managing the situation along with its international partners.

Becton said it’s important for producers to be aware of NWS.

“Even more importantly, if they observe any non-healing wound or draining wound or animals that aren’t doing well, report it to your herd veterinarian immediately,” she said.


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