New World Screwworm: A Resurgent Threat
The New World screwworm, a parasitic fly, is experiencing a resurgence. It is capable of inflicting severe wounds on livestock and humans. This resurgence has raised concerns among U.S. officials. This flesh-eating parasite, native to South America and the Caribbean, was largely eradicated from the U.S. and Central America through sterilization programs in the mid-20th century. However, recent detections in Mexico and a significant increase in cases across Central America since 2023 indicate a troubling comeback.
A Brutal Life Cycle Female screwworm flies deposit eggs in open wounds or orifices of warm-blooded animals. Upon hatching, the larvae burrow into the host’s flesh, feeding and causing painful wounds that can grow progressively larger. The larvae can lay up to 300 eggs at once, and their short lifespan allows for multiple breeding cycles. Unfortunately, there is no approved medical treatment for screwworm infestations, and physical removal of the larvae remains the only option.
A Regional Crisis Panama has been particularly hard-hit. Cases have surged from an annual average of 25 before 2023. There are now over 22,600 confirmed incidents as of December 2024. Costa Rica has also experienced a rise in human cases, including a fatality earlier this year. The U.S. Embassy in Costa Rica has issued warnings to travelers to take precautions to avoid screwworm infestations.
As the threat of screwworm infestation looms, health officials and agricultural authorities in the U.S. and Central America are closely monitoring the situation and implementing measures to prevent its spread. Travelers to affected regions should take preventive measures. This includes wearing protective clothing and using insect repellent. These steps will minimize the risk of infestation.
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