New World Screwworm Reaches US Border in Texas and Coahuila

USDA Confirms New World Screwworm in Zavala County, Texas

The U.S. Department of Agriculture this week confirmed the presence of New World screwworm in Zavala County, Texas. The report comes just five days after the USDA announced that a parasitic fly was found in a young sheep in the Mexican state of Coahuila within 31 miles of the U.S. border.

This detection marks the closest the parasite has come to the United States during the ongoing outbreak that has tracked north from Central America through Mexico for more than a year. Rural families along the border now watch their herds with new concern as the pest threatens livelihoods tied to cattle and sheep.

Details of the Texas Calf Case and Immediate Response

In a statement released on Wednesday, the USDA said the affected animal in Texas is a 3-week-old calf and larvae were identified in its umbilical area. With the recent detection of New World screwworm in a 3-week-old bovine in Zavala County, Texas, USDA urges residents to contact your veterinarian right away if you see any suspicious wounds, maggots, or infestations in your animals or herd.

Communities in northern Mexico and southern Texas share deep ties through cross-border ranching. A single case like this can ripple through families who depend on healthy calves for income, reminding everyone how quickly a parasite can disrupt daily life in the colonias and ranchos near the line.

Coahuila Detection Brings the Pest Within 31 Miles of the Border

Until this week, the Coahuila case in a young sheep stood as the closest the parasite had come to the U.S. during the current outbreak. Mexican ranchers in the region have already faced months of vigilance as the fly moved steadily northward despite joint containment efforts.

The news hits hard in Coahuila’s rural communities where families raise livestock on small plots and ejido lands. Parents who once felt the border offered a buffer now see the threat sitting practically at their doorstep, affecting everything from household budgets to plans for the next season’s herd.

Economic Stakes Rise for Mexican and U.S. Cattle Producers

If the fly enters the U.S., record beef prices could surge higher since more calves would be kept out of the U.S. cattle supply. The USDA estimates that an outbreak could cause billions of dollars in damage to the U.S. economy and Texas could suffer economic losses of US $1.8 billion.

These figures matter deeply to Mexican producers who supply cross-border markets. Small business owners and campesinos on both sides of the Rio Grande feel the pressure as past suspensions of cattle imports over the past 18 months have already strained local economies and family operations.

Human Cases Climb Across Mexico With New Reports in Nuevo León and Mexico City

Mexico’s Health Ministry said there have been more than 350 cases of human infestation across Mexico, with Chiapas being the most affected state with 131 cases. On May 27, the ministry reported the first case of New World screwworm infestation in humans in Mexico City, and this week it reported the first case of screwworm myiasis in a human in Nuevo León.

Pets, wild animals, and humans can also be affected. In states like Chiapas and now Nuevo León, families in rural areas must stay alert while tending animals or working outdoors, knowing the larvae burrow into open wounds and eat living tissue if left untreated.

World Cup Preparations Add Urgency to Prevention Advice

As hosts of the upcoming World Cup, both Mexico City and Nuevo León are expecting millions of visitors in this month and next. The Health Ministry has recommended using protective clothing, such as long sleeves and pants, when visiting the countryside or near animals, as well as using authorized repellents on skin and clothing to prevent the presence of flies.

These practical steps now reach beyond local ranchers to everyday residents and visitors. Communities preparing to welcome the world understand that protecting health means protecting the warmth and hospitality that define Mexican gatherings, from family meals to larger celebrations.

Historical Success Offers Hope for Border Communities

The infestation was eradicated in Mexico since 1991, while the U.S. eradicated New World screwworm in the 1960s. The United States has defeated this pest before, and we will do it again, said Dudley Hoskins, a USDA official, adding that USDA invested heavily in the tools needed to eliminate NWS ever since cases started increasing in Central America and Mexico.

That shared history resonates with Mexican families who remember earlier victories over the pest. Today’s challenge calls on the same spirit of cooperation between neighbors on both sides of the border to protect herds, homes, and the next generation of ranchers.

Tags: New World screwworm, Coahuila, Texas, USDA, human cases, World Cup, livestock, border communities

By Rosa Martinez, Staff Writer