Canada Bans Texas Cattle Amid Flesh-Eating Screwworm Outbreak in the US

Canada bans Texas cattle over flesh – Canada’s food inspection agency has imposed a temporary ban on livestock from Texas following the discovery of flesh-eating screwworms in calves. The move, outlined in an official statement, targets cows and horses that entered the country within 21 days of being in Texas. This precautionary measure aims to prevent the spread of the parasitic fly, which poses a significant threat to the agricultural sector. The ban follows the US Department of Agriculture’s (USDA) confirmation of a second case in the state, marking a resurgence of the parasite after decades of absence.

Outbreak in Texas

The first reported case of the New World Screwworm in Texas was identified in a three-week-old calf in La Pryor, a town located about 30 miles (48km) from the Mexico border. The larvae were found in the calf’s umbilical area, raising concerns about the parasite’s potential to spread further. This week, a second calf in Zavala County, approximately 5.6 miles (9km) from the initial discovery, tested positive for the infestation. The USDA noted that these cases were identified during routine inspections of suspected animals.

“This is likely to spread over the course of the summer,” said Texas Governor Greg Abbott, who declared a state of disaster on Friday to address the “imminent threat” the outbreak represents. The declaration emphasizes the urgency of containing the parasite, which could disrupt the state’s leading role in the US beef and cattle industry.

The New World Screwworm, scientifically known as *Cochliomyia macellaria*, is a parasitic fly whose females lay eggs in open wounds or mucous membranes of living animals, including humans. Once the eggs hatch, the larvae feed on tissue using their sharp, mouth-like structures, often leading to the death of the host if left untreated. These flies are typically found in warmer, humid climates, where they thrive and reproduce rapidly.

US Response and Containment Measures

In response to the outbreak, US officials have established a 20km-wide control zone around the initial case and implemented strict quarantines, movement restrictions, and intensified surveillance. The USDA’s strategy includes the release of genetically modified sterile flies to reduce population growth and the use of trained detection dogs to identify infected livestock. These efforts are part of a broader initiative to combat the parasite, which has been spreading through Central America and Mexico.

While the screwworm was once eradicated in the US by 1966, it reemerged in the 1970s and has since been monitored closely by agricultural and health authorities. The recent resurgence highlights the challenges of maintaining control over such a widespread infestation. Officials in Latin America have also been working to manage the parasite for much of the past six decades, though with limited success.

Experts are cautious about the effectiveness of these measures. The release of sterile flies, while a promising technique, depends on precise timing and consistent implementation. Meanwhile, sniffer dogs offer a more immediate way to detect infestations, but their use is limited by resource availability. Governor Abbott’s declaration of a state of disaster underscores the economic and ecological stakes involved, as the outbreak threatens to disrupt Texas’s cattle industry and its cross-border trade with Canada.

Impact on the Canada-US Cattle Trade

Canada and the US have a substantial two-way cattle trade, with livestock frequently moving across the border for slaughter, breeding, and dairy production. In 2025 alone, over 550,000 cattle were imported from the US, according to Canada’s agriculture department. The current ban on Texas cattle, however, may affect this flow, particularly as Texas is a major producer of beef and a key player in the industry.

Canadian officials have expressed confidence that the colder climate will limit the parasite’s spread within the country. Still, they have urged farmers to remain vigilant, monitoring their animals for wounds or cuts accompanied by discharge or an unpleasant odor. Pet owners traveling to Texas are also advised to check their animals for signs of infestation, as the parasite can affect both livestock and domesticated species.

Despite the risks, the ban is expected to be temporary. The USDA has already begun addressing the outbreak, and the control zone strategy aims to contain the infestation before it reaches Canadian borders. The agency’s focus on movement controls and surveillance reflects the gravity of the situation, as the parasite’s ability to travel short distances through natural means makes it a persistent threat.

Historical and Global Context

Historically, the New World Screwworm has been a major concern in tropical and subtropical regions, where its lifecycle is supported by warm temperatures. The parasite’s ability to hitchhike on animals or through human activity has made it a challenge for countries to eradicate completely. In Texas, the reemergence of the infestation suggests that even with advanced monitoring systems, the parasite can resurface unexpectedly.

While the US has made progress in managing screwworm outbreaks, the recent cases in Texas indicate that the threat is far from eliminated. The USDA’s plan to release millions of sterile flies, combined with targeted testing and quarantine measures, is a critical step in curbing the spread. However, some experts question whether these tactics will be sufficient, especially as the parasite continues to move through Central America and into Mexico.

The outbreak also highlights the interconnectedness of global agricultural systems. As the parasite spreads, it could impact not only the US and Canada but also neighboring regions that rely on cattle exports. Canadian officials are now emphasizing the importance of proactive measures to prevent any potential incursions, ensuring the country’s livestock remains safe from the invasive species.

The discovery of the screwworm in Texas has sparked a coordinated response between the US and Canadian authorities. While the US has focused on localized containment strategies, Canada’s ban serves as a preventive measure to safeguard its own agricultural infrastructure. The economic implications of the outbreak are significant, given the volume of cattle traded between the two nations. Continued vigilance and international collaboration will be essential in mitigating the spread of this parasitic fly and protecting the livestock industry from further damage.