The New World screwworm, a flesh-eating parasite eradicated from the US in 1966, is resurfacing in Central America and threatening to re-enter the US. The USDA, initially using sterile male flies to create a biological barrier in Panama, is shifting its strategy to focus on Mexico due to the outbreak's northward spread. This change has sparked tension with Mexico, which is restricting US access for fly dispersal. The USDA has secured emergency funding, but the long-term success hinges on US-Mexico cooperation and strengthening regional controls.

Prepared by Olivia Bennett and reviewed by editorial team.