Timeline for Central America
Mentioned in: Screwworm cases in Mexico rise fivefold
Pandemics and BiosecurityBackground
Central America is the isthmus of seven countries between Mexico and Colombia: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama.
It is the route of New World screwworm's return north. The fly was wiped out in North and Central America with releases of sterile flies, and a barrier zone was pushed south to Panama's Darién Gap from 2006. That barrier was breached in 2023, partly because cattle moved north illegally through Central America carrying larvae past the sterile-fly zone. Once breeding populations formed in Guatemala and southern Mexico, sterile-fly supply could no longer cover the area. The COPEG plant near Panama City was the region's only sterile-fly producer until a second opened at Metapa, in Chiapas, Mexico, in June 2026.
The cost now lands north of the isthmus. Mexico recorded 575 human cases in 2026 to 18 September, and Chiapas, on the Guatemalan border, had the most, at 165. Guatemala also has the Americas' largest measles outbreak of 2026, with 33,866 cases and 45 deaths by 19 September.