Detected in Ottawa, not monitored in Gatineau

“Systematic trapping and screening for mosquitoes for the Western Nile virus (VNO) have confirmed the presence of a group of positive mosquitoes in Ottawa,” Ottawa Public Health wrote in a statement on Tuesday.

This is the first confirmation of the presence of the virus on the territory of Ottawa this year, since the city’s public health agency began its seasonal surveillance in June. The positive cases of VNO in mosquitoes have been captured in the traps for this purpose.

The hot and humid conditions as encountered in the capital region this last week are conducive to the proliferation of mosquitoes Culex tarsalis et Culex pipiens-restuansmain vectors of the Western Nile virus.

No response in Outaouais

On the side of Gatineau and the Outaouais, it is difficult to say if the Western Nile virus is currently present on the territory.

The right Contacted the Integrated Health and Social Services Center (CISSS) of the Outaouais and the city of Gatineau to try to have the data. The two administrations pointed out in the direction of the other to obtain these answers.

The Cisss de l’Outaouais explains that it has surveillance of mosquitoes until 2021, before putting a break on the program. The agency advises us to contact the city of Gatineau to find out if it does control activities.

“The monitoring of mosquitoes carrying the Western Nile virus is of government jurisdiction, on the public health side of Quebec,” replied the Communications Service in Gatineau.

In 2023, the city of Gatineau put an end to the biological control program for mosquitoes, by prohibiting the spread of Bacillus thuringiensis israelensis (BTI), an insecticide with a bacterial base. However, this program aimed more at improving the quality of life of residents than controlling the viruses carried by these disturbing insects, according to the communication of the municipality.

The Cisss de l’Outaouais still specifies having the appearance of the virus and other infections transmitted by mosquitoes thanks to “surveillance of cases in humans, in wild animals (certain birds) and in domestic animals (especially horses).”

The VNO has already been identified in the past in the entire territory of the municipalities of Gatineau, Pontiac, Fishing, Val-des-Monts, Ripon, as well as several places in Cantley, Chelsea and the Ange-Gardien, between 2002 and 2023, according to the map of the National Institute of Public Health of Quebec (INSPQ).

According to the Quebec Ministry of Health, entomological surveillance has been paused in the province in order to allow the scientific group on diseases transmitted by the mosquitoes of the Insq to find a better seasonal surveillance strategy.

This year, for the moment, there was only one case of human infection by the virus in Canada, in Toronto, detected in early August.

No human infection has yet been reported in the region, in Ottawa or Gatineau in 2025.

Last year, 14 mosquito traps in Ottawa confirmed the presence of the VNO during the virus activity season, and two human cases were reported. In addition, an Ottavian died after having contracted the East Eastern Encephalitis (EEE), another disease transmitted by mosquitoes.

In Quebec, seventy people have been affected by VNO in 2024, a record since 2018. None was however in Outaouais.

According to the Quebec Public Health Agency, the proliferation of VNO risks increasing significantly in the coming years due to climate change and the rise in temperatures, especially in southern Quebec.

The Western Nile virus was isolated for the first time in 1937 in Uganda. He has been present in Canada since 2022.