WOAH sounds alarm on New World screwworm expansion
The World Organisation for Animal Health (WOAH) is sounding the alarm as New World screwworm (Cochliomyia hominivorax) continues to spread across Central America. Since its resurgence in Panama in June 2023, the parasitic fly has been detected in Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Mexico, with over 20,000 new outbreaks reported in WOAH’s information system.
This zoonotic disease affects animals, humans, and the environment, posing serious economic and health risks. There is no vaccine available, and control depends on:
Thorough animal inspections and wound treatment
Quarantine and certification for animal movement
Preventive measures such as spraying or dipping animals with approved insecticides
Eradication efforts often use the sterile insect technique, which has been successful in the past.
WOAH emphasizes a One Health approach—uniting veterinary, public health, environmental, and border authorities to:
Strengthen surveillance and diagnostics
Enforce transparent, timely reporting
Prevent illegal animal movement and ensure proper medical care for affected humans
The disease can impact wildlife as well as domestic animals, with a recent case confirmed in a bird of prey in Mexico (April 2025).
WOAH urges countries to follow its Animal Health Terrestrial Code and leverage expertise from the WOAH Reference Laboratory for NWS (COPEG, Panama).
Failure to contain this outbreak could lead to severe animal losses, human infestations, and major economic consequences across the Americas.
