Guard against screwworm: What you need to know

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New World screwworm

New World screwworm (NWS) is spreading northward in Mexico, prompting the U.S. Department of Agriculture (USDA) to suspend live animal imports through ports of entry along the southern border. A new AVMA resource spells out what veterinary professionals need to know to recognize and respond to this flesh-eating fly should it breach the border.

Why does screwworm matter, and why now?

New World screwworm is a serious cause for concern. Its larvae infest open wounds and orifices of warm-blooded animals, burrowing into the surrounding tissue and causing extensive damage, severe pain, and possibly death if left untreated. Livestock, pets, wildlife, and people are susceptible, although human infestations are rare.

Animals at greatest risk include those that have recently given birth, have open wounds, or have undergone surgery or management procedures like dehorning or branding.

Once widespread throughout the Americas, NWS was eradicated from the U.S., Mexico, and most of Central America between 1966 and 2006. Unfortunately, although a biological barrier in Panama successfully contained NWS to South America for decades, the parasite broke through in 2023. Since then it has been confirmed in every Central American country and Mexico, heightening the risk of reintroduction to the U.S.

What can we do?

The situation calls for vigilance and immediate response. Veterinarians will play a critical role in this frontline defense.

Are you ready?

AVMA’s New World screwworm webpage delivers the key information veterinary teams need to stay ahead of this emerging threat:

  • Clinical signs to watch for
  • How to test and report suspected cases
  • How to treat affected animals
  • How to prevent NWS from spreading

Get informed, stay alert, and be prepared.

Get NWS info
 

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