New World Screwworm, a devastating parasite that eats cattle and other wild animals alive, is traveling north from Central America to Mexico and has crept past biological barriers that kept the pest contained for decades, experts said.
Washington halted cattle imports from Mexico in May, citing the insect’s spread further into Mexico, about 700 miles from the Texas border. With the U.S. cattle herd already at a multi-decade low, the closure could further elevate record-high beef prices by keeping more calves out of the U.S. cattle supply.
When screwworms infect a cow, a tiny scrape, a recent brand or a healing ear tag can quickly become a gaping wound, carpeted with wriggling maggots that put the entire herd at risk of infestation. Screwworms were eradicated from the U.S. in the 1960s when researchers began releasing massive numbers of sterilized male screwworm flies who mate with wild female screwworms to produce infertile eggs.
Eradication =/= extermination. The latter means zero left alive on the whole planet. The fact that the US stopped at clearing screworms from only North America while leaving them alive in the south (and Cuba) always left the possibility of this happening.
Both of those words are used synonymously. Never mind you have to take into account that eradicating screwworms for 60+ years was about as good as it could get … especially considering that in the 60s nobody knew about global warming and the migratory effect it would have on pests and diseases.