New World screwworm (NWS) is a nasty flesh-eating parasite that feeds on the living tissue of animals. Once infected, the parasites can cause severe infection and death in livestock.
The U.S. has successfully kept NWS out since 1966, but cases have been rising rapidly in Mexican cattle over the past year. Just this week, the first U.S. case was found in a calf in South Texas, near the border.
NWS isn’t generally considered a food safety issue. The screwworms don’t actually infest meat (only living tissue), and FSIS inspections add another layer to prevent meat from infected cattle from entering the food supply. Still, it’s a major concern for the livestock and beef industries - particularly rough with beef already at record high prices. The pace at which cattle have been affected in Mexico is concerning, and could lead to major shortages and price hikes if left unchecked.
NWS isn’t contagious between animals - rather, female flies lay eggs in the wounds or body cavities of animals and then those larvae can go on to cause serious infections (sorry, gross, we know!). The main method for preventing NWS is releasing sterilized flies into the wild to prevent them from successfully reproducing, which the U.S. has already started to do. There are plans to open a $750 million facility next year to produce hundreds of million of sterilized flies each week (though some ranchers and politicians worry it will be too late). There’s also a quarantine zone enacted around the farm where the calf was infected, and a drug that can help prevent and treat infected animals, but the next week or two will be telling in terms of how serious an issue this turns out to be.
Human cases are rare, but possible - there was one travel-related case last year in Maryland that made a full recovery, but cases can be fatal if left untreated. People who work with livestock are at highest risk.
In short, New World screwworm isn’t a serious food safety or human health risk, but it may end up being very damaging for livestock industries and cause a spike in beef prices. We’ll keep a close eye on it and keep you updated as this unfolds.
Sources: NBC, USDA, CNN, APHIS
We’re less than a week out from the World Cup, and that means public health departments in host cities and around the country (as well as Canada and Mexico) are working overtime to prepare for an influx of international visitors. Ebola is on their mind, but mandatory quarantine periods and travel screening make it lower risk. Measles, dengue, and foodborne illness are much more likely issues.