Calgary company steps up to help combat screwworm in U.S.

Calgary-based company Solvet can now sell its equine ivermectin product in the United States to help combat screwworm.

In July, the U.S. Food and Drug Administration (FDA) granted Solvet emergency use authorization for its ivermectin liquid for horses.

“It's an aqueous-based solution, not a paste, so it's a bit unique; it's a bit more concentrated and it's a lot easier to administer, ” said Lionel Gibbs, CEO of Solvet.

The business was founded in 2009 by two former University of Calgary professors, and has since grown into one of Canada's largest veterinary pharmaceutical companies.

Ivermectin, the now infamous anti-parasitic drug , is commonly used to combat a broad range of parasites, including screwworm, which is actually a species of fly native to parts of North America.

Female screwworm flies lay eggs on open wounds of mammals including horses, cattle and sometimes humans. The larvae hatch and bore into the host, feeding on tissue, giving the fly its name and also causing severe pain, secondary infections and possibly death.

Screwworm regularly cost ranchers in the United States and Mexico millions of dollars in annual losses until it was successfully eradicated from North America using what is called sterile insect technique.

The tactic takes advantage of the fact that screwworm females mate only once in their lifetime and store the sperm to fertilize their eggs. Beginning in the 1960s, fly factories were built to raise and sterilize male flies en masse.

Billions of these were released into the environment, and by mating with females eliminated subsequent generations of flies. By 2006 screwworms couldn’t be found north of the Panama Canal.

In 2024 the fly was reported in Central America, then Mexico, and has moved north, triggering alarms across the southern United States.

In June 2026 the discovery of screwworm larvae on a calf in Texas prompted the Canadian Food Inspection Agency (CFIA) to halt imports of animals from the state . In an email to CBC News, the agency said, “Animals that originate from, or were present in, the State of Texas within 21 days prior to entering Canada are not permitted entry.”

Production of sterile males has restarted in the U.S., but it will take time to produce numbers capable of eradicating the fly again.

“The FDA recognized that screwworm was a real risk, and they wanted to protect their food supply, their producers and everything. So they put out a call to pharmaceutical companies,” said Gibbs.

After a rigorous process assessing Solvet’s facilities, manufacturing procedures and data on their ivermectin liquid, an emergency authorization was granted.