Quebec lags behind Ontario in monitoring disease-carrying mosquitoes

Quebec has cut its mosquito surveillance program, while Ontario is taking drastic measures to reduce outbreaks of mosquitoes responsible for transmitting a rare but deadly disease.

The announcement of the first Canadian death from Eastern Equine Encephalitis (EEE) in an adult from Ottawa on August 31 did not surprise entomologist Richard Trudel, who knew that insects in the region carried the virus. But he does not understand why Quebec is not more proactive in terms of prevention.

“Every week, at least 10 cities in Ontario have tens of thousands of mosquitoes analyzed to identify carriers of diseases transmitted to humans. Nothing like that in Quebec, which ended the entomological surveillance program several years ago,” he denounced in an interview with Newspaper.

Ironically, it is in the laboratory of his employer, GDG Environnement, in Trois-Rivières, that the Ontario samples, which see up to 1.3 million insects per year, are analyzed. They detect the DNA of the EEE, but also that of the West Nile virus and other pathogens.

The Quebec Ministry of Health and Social Services (MSSS) confirms that the entomological surveillance program was stopped in 2021 because it did not allow “predicting the intensity of the mosquito-borne disease season” according to its spokesperson, Francis Martel.

Ottawa spreads

Yet across the Ottawa River, Ottawa Public Health is implementing a “control plan to reduce the risk of infection by West Nile virus and Eastern equine encephalitis virus,” which consists of several measures, including the spraying of biological and chemical larvicides.

But not in Quebec, where “no larvicide spreading activity is carried out by the government,” continues Francis Martin of the MSSS, who adds that this measure has not proven its effectiveness.

A statement that makes entomologist Trudel jump, who can cite several contradictory studies on the issue. Holder of a doctorate from Laval University on forest entomology, he has been conducting work on biological control of insects for over 20 years.

More insects present

Studies show that pathogens like the one that caused the death in Ottawa, as well as West Nile virus and others, may be more prevalent in the north because of global warming. There are at least 63 species of mosquitoes currently in Quebec, and that number is expected to grow.

Veterinarian Jean-Philippe Rocheleau, who advises authorities on the risk of mosquito-borne diseases, is reassuring. “The virus has been present in Quebec for a long time. It caused several deaths among horses between 2008 and 2010.”

He believes that spraying biological larvicides such as BTI can be part of preventative solutions if new cases arise. “It’s a proven method,” he says.

In the meantime, he reminds us of the basic rules of protection: protect yourself from bites with clothing that covers the skin well and apply mosquito repellent.

The EEA in brief

· Eastern equine encephalitis (EEE) has been known since 1938 and is named after the first case, identified in horses on the east coast of the United States.

· A vaccine exists for horses, but no treatment is known for humans.

· Symptoms are similar to those of the flu: fever, headache, body aches.

· 30% of infected people die due to brain rupture.

· The Ottawa resident’s death came weeks after another death in Hampstead, New Hampshire. The state has since confirmed another, but non-fatal, human infection in Kensington.

· New Hampshire, which tests thousands of mosquitoes each year, reports 15 clusters of carrier mosquitoes in 2024. Since 2020, that number has ranged from zero to two.