Calgary & West Nile: early detection during wet & warm summer
Posted Jul 27, 2026 9:15 am.
Researchers with the University of Calgary say they collected the city’s first West Nile-positive mosquito sample at the end of June, which is the earliest detection of the virus in the last few years.
Experts also say heavy rainfall in Calgary this year has led to a steep increase in mosquitoes found in traps compared to June and July last year.
The positive West Nile sample came from the northern house mosquito; an invasive species which was first detected in Calgary in 2022.
“That mosquito actually does not respond as much to rain as others. It still does benefit from it but because it uses habitat that we often leave around cities or require in cities, including things like drains and things, our stormwater ponds, or the catch basins, that allows that mosquito to survive drought conditions a little bit better than other mosquitoes,” says Dr. John Soghigian, an associate professor of parasitology.
Soghigian says while early detection of West Nile virus is concerning, most people infected with the virus don’t develop symptoms and some experience a mild illness. In rare cases the virus can cause serious neurological disease in older adults, those with a weakened immune system and young children.
He advises people to focus on taking precautions such as wearing long sleeves and loose-fitting clothing to reduce exposed skin and the use of insect repellants containing DEET.
