Key facts
- A second case of the New World screwworm parasite was confirmed in Zavala County, Texas.
- The second case was detected on a ranch 5.6 miles from the first confirmed case.
- Fears of screwworm infestation are driving a rally in U.S. cattle futures.
- Canada has temporarily blocked livestock imports from Texas.
- The USDA is leading containment efforts, including releasing sterile flies.
A second case of the New World screwworm parasite has been confirmed by the U.S. Department of Agriculture (USDA) in Zavala County, Texas. This new case was detected on a ranch located 5.6 miles from the first positive case of screwworm in Texas, which the USDA had confirmed earlier in the week. The infected animal in the second case was a one-month-old calf. Screwworms are parasitic flies whose larvae infest open wounds or mucous membranes of warm-blooded animals, penetrating living tissue and potentially causing fatal damage if untreated. The proximity of the two cases, following the pest's northward movement through Mexico over the past year, has heightened concerns for U.S. cattle ranchers. Fears of a potential screwworm infestation are contributing to a rally in U.S. cattle futures due to anticipated supply chain disruptions. Consequently, Canada has temporarily blocked livestock imports from Texas. The USDA is actively engaged in containment efforts, which include deploying workers to set fly traps and release sterile flies to halt the parasite's reproduction. An outbreak in U.S. border states in the 1960s devastated wildlife and inflicted heavy financial losses on ranchers. A widespread resurgence now could pose a significant economic threat in Texas, the country's largest cattle-producing state, through animal deaths as well as higher labor and treatment costs. To limit the risk, Washington has kept the U.S.-Mexico border closed to live cattle imports for more than a year and has spent millions of dollars to curb the pest's northward spread.