How A Nasty Parasite Called The Screwworm Is Literally Screwing With Beef Prices

The nasty New World screwworm that bores into the flesh and tissue of cattle, often killing them, is adding to a perfect storm of conditions fueling record beef prices at the grocery store.

These parasites are flies that lay eggs in open wounds. The maggots bore deep into the flesh of cattle and other livestock, “like a screw being driven into wood,” causing serious and often fatal infections, according to the USDA Animal and Plant Inspection Service.

Importantly, the screwworm hasn’t been detected in U.S. cattle herds in the current outbreak. But its rapid spread in Mexico prompted the USDA to close southern border ports to livestock trade in May, cutting off a key market for U.S. ranchers struggling to meet consumer demand for beef as the domestic cattle inventory at a 70-year low.

The Food and Drug Administration’s conditional approval this week of a cattle-only injection to treat and prevent screwworm infections also illustrates the urgency in limiting what many experts say is the almost certain migration of the screwworm to the southern U.S., with climate change playing a major role.

It’s not the only pressure fueling record beef prices at the grocery store, but the export halt adds another significant break in the supply chain that is being felt from local sale barns to grocery store aisles. Tariffs, especially the combined 76.4 percent duty on beef from Brazil, have further tightened the supply of beef in the United States.