First US screwworm case in 60 years: Should America be worried?

Key Points:

• The New World screwworm, a flesh-eating parasite previously eradicated in the US since 1966, has been detected in a calf in Texas, marking the first confirmed animal case in six decades and raising concerns about its spread from Central America through Mexico.
• Screwworm larvae infest wounds of warm-blooded animals, causing painful, rapidly enlarging sores that can lead to severe tissue damage or death if untreated; humans can also be infected, although cases are rare.
• Authorities have established a 20km quarantine zone around the affected Texas farm, are treating the infested calf, and emphasize vigilance, isolation, and sterile male fly release as long-term control measures.
• The outbreak threatens the livestock industry and could cause significant economic losses, with the USDA estimating up to $1.8 billion in damages to the Texas economy and potential further increases in already high beef prices due to supply disruptions.
• Factors contributing to the parasite’s resurgence include disruptions in sterile-fly control programs during the COVID-19 pandemic, increased livestock movement, and favorable weather, complicating efforts to manage and prevent further infestations.