The Canadian Food Inspection Agency (CFIA) has announced temporary restrictions on imports of livestock from Texas following the discovery of a dangerous pest, blowfly maggots, in the US state. This parasite affects both farm and wild animals, and in rare cases can pose a threat to humans.
According to the new rules, animals that were raised or stayed in Texas within 21 days before arriving at the US-Canadian border cannot be imported into Canada.
Although the so-called New World screwworm, as these larvae are also called, is not found in Canada, experts note that during the summer climatic conditions in the country may temporarily favor the survival of the parasite. Hot and humid weather at temperatures between 25 and 30 °C is most favorable for blowfly breeding.
“The larvae of this parasitic fly, which feed on living flesh, pose a serious threat to the lives of infected animals. Although Canada's cold climate is not suitable for the pest's permanent existence, it can survive for short periods of time in the summer. Therefore, the introduction of restrictions is considered as a reasonable measure to prevent the entry of the parasite into the country and protect animal health,” the statement said.
The agency urged pet owners and veterinarians to closely monitor for possible signs of infection. The parasite enters the body through open wounds, so increased inflammation and deterioration of damaged tissue may indicate the presence of larvae. Canadians traveling to Texas with pets are also advised to have their pets examined regularly.
CFIA will continue to work closely with our US counterparts to assess the situation and adjust measures as necessary. Several US states have also taken preventative measures to reduce the risk of the parasite spreading.
Distribution of blowfly larvae in the United States
The first case of screwworm in Texas was detected June 3 in cattle in Zavala County. The larvae were found in the umbilical region of a three-week-old calf, RTVI.US previously reported. On Friday, a second infection became known. The parasite was also detected in a calf during an investigation into suspicious cases, Newsweek writes.
A quarantine zone has been introduced around both outbreaks. The movement of animals outside its boundaries is prohibited without prior inspection. The US Animal and Plant Health Inspection Service and the Texas Animal Health Commission continue to look for signs of infection in other animals in the surrounding area, as well as collect suspicious samples.
Texas Governor Greg Abbott expanded the state of emergency to the entire state and ordered the use of “all available resources” to combat the threat if necessary. It is planned to accelerate the introduction into the population of male flies infected with a special bacterium, which, when mating with females, sterilizes them and prevents the reproduction of the pest.
Unlike most maggots, which feed on dead tissue, screwworm larvae infect healthy tissues of the body, which often leads to the death of the animal. Females lay eggs in open wounds and even small scratches, and the larvae appear within a few hours. Characteristic signs of infection include painful sores and the presence of larvae in the nose, ears, genitals or navel of newborn animals.
The blowfly is most often found in South America, some Caribbean countries, and more recently in Central America and Mexico, Newsweek notes. The parasite spreads mainly through the movement of infected animals.
U.S. federal and local officials and the cattle industry have been warning about the threat of the parasite moving through Mexico to the U.S. border for nearly two years, since November 2024, when the infection was confirmed in southern Mexico, the Associated Press reports.
Over the course of several years, the parasite infected more than 171,700 animals and 2,070 people in Central America. A total of 10 human deaths were reported.
A year ago, US authorities closed the border to Mexican livestock to curb the spread of the disease. Before the restrictions were introduced, the country imported more than a million head of cattle from Mexico annually, representing about 4-5% of the total volume of animals used for beef production. After importation, the animals were fattened on American farms and then sent to meat processing plants.
The border closure overall has hit the $100 billion U.S. beef industry, as Texas is a leading cattle-producing state. At the same time, Mexican producers, despite the fact that the screwworm has already infected almost 28,000 animals, have taken advantage of the situation to expand local feedlots and meat processing plants, writes Reuters.
