Canada’s Food Inspection Agency announced a temporary ban on livestock from the U.S. state of Texas after flesh‑eating screwworms were discovered in calves this week.
Livestock that traveled from Texas within the past 21 days before crossing the Canada–U.S. border will not be allowed into the country, the agency released in a statement on Tuesday.
The outbreak was first reported in a three‑week‑old calf in La Pryor, Texas, about 30 mi (48 km) from the Mexican frontier. A second case, in a one‑month‑old calf in Zavala County, was identified only five days later, bringing the total to two infected animals.
The New World Screwworm (Chrysomya nigripennis) is a parasitic fly that lays eggs on open wounds and mucous membranes of mammals. The larvae burrow through living flesh, often killing the host if left untreated.
Officials in Texas have declared a state of disaster, deploying quarantines, movement restrictions and surveillance across a 20 km‑wide control zone. The U.S. Department of Agriculture (USDA) is conducting intensive testing and plans to release genetically modified sterile flies and deploy sniffer‑dogs in an effort to halt the population growth.
Canadian authorities note that the parasite’s range is limited by cold weather, but advise farmers to monitor livestock for wounds that discharge or emit foul odor, and to examine pets that have traveled to Texas.
The ban could affect the two‑way cattle trade that has grown in recent years, with 550 000 cattle imported from the United States to Canada in 2025, according to Agriculture Canada. The measure underscores the delicate balance of cross‑border food safety amid emerging threats.
