New World Screwworm Detected in Texas

June 5, 2026

On June 3, 2026, United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed a single case of New World Screwworm (NWS) in Texas. The USDA APHIS has invested significantly in preparedness and has communicated their plans. They have enacted their response plan and are working to prevent spread to other animals.

There is currently minimal risk to animals or people in Canada. Canada has strong safeguards and response plans in place to protect livestock and maintain our animal health status.

Mid-afternoon on June 5, the Canadian Food Inspection Agency (CFIA) announced that it will implement temporary import restrictions on livestock, including horses, from entering Canada from affected areas. See www.canada.ca/en/food-inspection-agency/news/2026/06/the-canadian-food-inspection-agency-implements-disease-control-measures-to-prevent-spread-of-new-world-screwworm.html for details. Should additional changes be announced, CCA will share updates as they are available.

What is New World Screwworm?

The New World Screwworm (NWS) is a parasitic fly. The larvae infest living tissue of warm-blooded animals, including cattle. Larvae feeding causes severe tissue damage and potentially death if untreated.

In the United States, NWS is classified as a foreign animal disease and is immediately reportable to USDA APHIS. This detection has triggered a coordinated federal–state response.

What Does This Case of NWS in the USA Mean for Canada?

Canada is free of the New World Screwworm. The screwworm parasite is an immediately notifiable disease in Canada and Canadian laboratories are required to contact CFIA regarding the suspicion or diagnosis of the disease. Canada’s risk of sustained NWS establishment remains low due to climatic limits, particularly intolerance to prolonged cold temperatures, alongside strong import controls and Canadian Food Inspection Agency (CFIA) oversight.

Information for Canadian Beef Producers

Producers should monitor imported animals for signs of NWS. Symptoms include foul‑smelling wounds, visible maggots, irritation, and lesions around the navel, ears, and common management sites such as branding, castration or dehorning. This fly is unique because the maggots feed on living flesh.

Producers are advised to take the following actions:

• maintain accurate records of animal movements (origin, destination, and movement dates)
• quarantine imported animals and monitor closely
• maintain fly control and wound management
• remove hazards that could cause injuries
• immediately report suspected cases to your veterinarian. Suspected cases should be isolated and not moved off premises.

Beef Cattle Research Council has an excellent collection of biosecurity resources at www.beefresearch.ca/topics/biosecurity. Practicing biosecurity and monitoring your cattle are the best ways to protect cattle from disease and infection.

The disease does not pose a risk to food safety, and Canadian food products, including meat and milk remain safe to eat.

Resources

Canadian Food Inspection Agency (CFIA) — New World Screwworm (Immediately Notifiable Disease)
https://inspection.canada.ca/en/animal-health/terrestrial-animals/diseases/immediately-notifiable/screwworm

USDA APHIS — New World Screwworm Response Playbook
https://www.aphis.usda.gov/animal-emergencies/nws