Updated

Updated · The New York Times · Jun 5

USDA Confirms 2nd Texas Screwworm Case, Expanding Response After First U.S. Detection Since 1960s

Updated

Updated · The New York Times · Jun 5

USDA Confirms 2nd Texas Screwworm Case, Expanding Response After First U.S. Detection Since 1960s

Q: As a flesh-eating parasite threatens Texas, are billion-dollar defenses enough to protect America's dwindling cattle supply?

Not yet. The U.S. has built a strong defense against New World screwworm, but the threat is close enough to Texas that success will depend on speed, surveillance and sustained investment, not money alone. There is no confirmed U.S. case at this point. Texas samples from two calves were sent to a federal lab after a suspected infestation, but both the USDA and Texas Animal Health Commission say screwworm is not confirmed in Texas or anywhere in the United States. Still, the parasite has moved steadily north through Mexico, with a confirmed case just 25 miles south of the Texas border in Coahuila and thousands of cases recorded across Mexico. The defenses are substantial. The U.S. has kept the border closed to cattle imports from Mexico for nearly a year, releases about 100 million sterile flies a week, and is expanding production capacity through facilities in Panama, Mexico and a new $600 million plant at Moore Air Base in South Texas. USDA researchers are also pushing a male-only sterile fly strain that could sharply improve efficiency. This strategy worked before: screwworm was eradicated from the U.S. in 1966 and a Florida outbreak was stamped out in 2017. But the risk is unusually high because the U.S. cattle herd is already at a 75-year low. A serious outbreak could cut supply further, lift beef prices and inflict an estimated $1.8 billion hit on Texas alone. The current defenses are credible and historically proven, but they are a containment system, not a guarantee.

Q: Is the northward spread of a tropical parasite a sign that climate change is breaching our agricultural defenses?

Not yet as proof, but it is a serious warning that climate change may be making agricultural defenses harder to hold. In this case, there is no confirmed New World screwworm in Texas or anywhere in the United States. Samples from two calves are still being tested, and U.S. and Texas officials say the parasite is not confirmed north of the border. What is confirmed is that screwworm has moved very close to Texas, with recent cases in Mexico only 25 to 62 miles south of the border. The evidence in the available reporting does not show climate change as the direct cause of this latest advance. The strongest documented drivers are animal movement and gaps in containment. Even so, some experts and officials say warming conditions are helping tropical pests and parasites survive farther north and for longer periods, which can increase the risk of establishment once they arrive. That matters because screwworm is exactly the kind of threat that tests agricultural defenses. The U.S. eradicated it decades ago, but now is relying on border closures, surveillance, trapping, and mass releases of sterile flies to keep it out. Those defenses are active, but the parasite’s return to northern Mexico shows they are under pressure. So the northward spread is better seen as a warning signal than a settled climate verdict: climate change is likely one risk multiplier, but the current evidence points more clearly to biosecurity and animal-transport pathways than to climate alone.

3 articles · Updated · The New York Times · Jun 5

A second New World screwworm case was confirmed in a one-month-old calf in Zavala County, about five miles from the first infected calf found days earlier.
Texas and the USDA are trying to contain the parasite by releasing millions of sterile male flies, a tactic meant to stop wild females from producing offspring and drive the population toward eradication.
Gov. Greg Abbott signed a statewide disaster declaration, saying the state is entering the season when spread is more likely and needs resources in place for what he called a difficult summer.
The discovery has rattled Texas cattle producers because the state has more than 4.1 million cattle and accounts for about 15% of U.S. beef production.
The outbreak threat lands as the national cattle herd is already at its lowest level since 1952, with drought, high feed costs and record beef prices straining the industry.