Calgary bug experts keeping tabs on mosquito capable of carrying West Nile virus

Mosquitos are known to be pesky creatures, but a particular species recently sighted in parts of Alberta may be more of a concern than others that are buzzing around.

The Culex pipiens, more commonly referred to as the northern house mosquito, has the ability to carry and spread West Nile virus.

The virus is primarily transmitted to humans through the bite of an infected mosquito and it can happen to anyone, according to Alberta Health. One in five people who are infected become ill, the agency said, adding that severe neurological illness associated with the virus is rare, but risk increases with age.

The northern house mosquito is a species that tends to be a container breeding species, laying eggs in things like tires or bird baths or grain barrels, said the city's pest management technician, Alexandra Coker. 

"That's why something like emptying containers that might be present in someone's backyard is a really important aspect associated with not just the species but other mosquitoes in general," she said.

The city first found the northern house mosquito last year through its regular monitoring. It's a species that's typically found in Eastern Canada, but it found its way to Edmonton in 2020 and has been spotted there again this year.

Mosquitos that carry the virus were also found earlier in other provinces across the country including Ontario, Quebec and Manitoba.

But there's no need to sound the alarm for Calgary this summer — just yet. 

The period of greatest risk of transmission to humans usually happens between mid-July and mid-August, according to the Alberta government's website.

Symptoms of West Nile virus can include severe headaches, high fever, stiff neck, confusions or reduced attention to surroundings, tremors or convulsions, muscle weakness or paralysis and coma.

Coker also noted the northern house mosquito is present a little later in the season — but added it's not the only species that can carry the virus. 

"We do have [Culex tarsalis], which is a local species," she said. "It tends to be more associated with agricultural areas, but we definitely do have it in Calgary." 

The weather this year, however, has resulted in a lack of mosquitos.

"Most of the mosquito species we have in Calgary are floodwater species. So they're really dependent on, sort of, that influx of rainwater coming in throughout the summer," Coker said.

"We really haven't seen a lot of rain … so we're just not seeing a lot of habitat."