TPWD encourages monitoring, reporting of animals affected by New World Screwworm

Texas Parks and Wildlife Department (TPWD) asks hunters and other outdoor enthusiasts in South Texas to monitor for animals affected by New World Screwworm (NWS) after a recent detection in Mexico.

This detection, found in a cow at an inspection checkpoint in the southern Mexico State of Chiapas, close to the border with Guatemala, follows the progressively northward movement of NWS through both South and Central Americas.

As a protective measure, animal health officials ask those along the southern Texas border to monitor wildlife, livestock and pets for clinical signs of NWS and immediately report potential cases.

What is New World Screwworm?

New World screwworms are larvae or maggots of the NWS fly (Cochliomyia hominivorax), that cause a painful condition known as NWS myiasis. NWS flies lay eggs in open wounds or orifices of live tissue such as nostrils, eyes or mouth. These eggs hatch into dangerous parasitic larvae, and the maggots burrow or screw into flesh with sharp mouth hooks. Wounds can become larger, and an infestation can often cause serious, deadly damage or death to the infected animal.

NWS primarily infests livestock but can also affect humans and wildlife including deer and birds.

The parasite was last eradicated from the U.S. in 1966, with costly efforts by federal and state animal health officials, livestock producers and veterinary practitioners. Eradication efforts have continued in Central America, but the pest is considered widespread in Cuba, Haiti, Dominican Republic and South American countries.

Clinical signs of NWS myiasis may include: • Irritated or depressed behavior • Loss of appetite

• Head shaking

• Smell of decaying flesh

• Presence of fly larvae (maggots) in wounds • Isolation from other animals or people • Transmission NWS infestations begin when a female NWS fly is drawn to the odor of a wound or natural opening on a live, warm-blooded animal, where she lays her eggs. These openings can include wounds as small as a tick bite, nasal or eye openings, navel of a newborn or genitalia.