Mexico reports sharp drop in screwworm cases
Sterile fly plant advances as US cattle ban holds
9 January 2026
1 minute read
By: Mexico's active cases of New World screwworm, a flesh-eating parasite that has kept the US-Mexico border closed to Mexican livestock, have fallen 57% since mid-December, Reuters reported, citing the country's agriculture ministry on Thursday.
Active cases dropped to 492 as of January 7, from 1,145 registered on December 10, the ministry said, overwhelmingly concentrated in a handful of states.
Construction for a factory to breed sterile flies in Chiapas state is 48% complete and is on track to start operating in the first half of this year, the ministry said, when it will produce some 200 million flies per week.
The flies will be released into the wild, so when sterile males mate with wild females, no offspring are produced and the population collapses over time.
The screwworm outbreak, which has moved northward through Central America and deep into Mexico, has strained relations with the United States, Mexico's biggest trading partner.
The US has kept its border mostly closed to Mexican cattle imports since May.
