Mexican Screwworm Cases Increasing

This week, Mexico reported that new screwworm cases in the country have jumped 50% since July of this year, and disease officials in the country have identified over 5,000 cases in animals, with 600 still active.

The USDA has announced a $680 million dollar plan to increase production of sterile screwworm flies, which are used to eradicate active cases of screwworms. A New World screwworm case was first identified in southern Mexico in November of 2024 which led to the border being closed to the importation of animal commodities. The border has been open and closed over the past nine months with the third suspension to animal traffic in July.

The border closings are straining the supply chain of cattle destined for the U.S. market.

00:01:48:20 - 00:02:15:10 Colin Woodall, CEO, National Cattlemen’s Beef Association:  “When you look at the U.S. beef cattle industry, it really is an integrated North American supply chain, including both Canada and Mexico. So any time there is a disruption with either our northern or southern border, it does have a direct impact on us as U.S. cattle producers. We have a lot of cattle feeders right now that are struggling to be able to keep their feedlots up and going because they cannot bring feeders out of Mexico. That, of course, could have a trickle down impact on whether or not we can maintain packing capacity in those areas.”

The parasites have been described as flying piranhas, which eat their hosts from the inside, and can kill a steer in seven to 10 days. Screwworms can also be spread by deer, feral pigs, and even birds. Warm blooded mammals can serve as hosts for the parasitic larvae which eventually develop into adult flies.

The screwworm was eradicated from the United States in 1966, and from all of Central America in 2001.   

For Market to Market, I’m Peter Tubbs.