Once temperatures and moisture levels line up, the province's most infamous summer pest will return in full force.
Dr. Bryan Cassone, a biology professor at Brandon University, says it’s remarkable how resilient mosquitoes are in surviving Manitoba winters.
"They're hardy," says Cassone. "They over-winter as either eggs or really early larvae stages depending on the species, and they're able to survive until conditions become favourable."
Cassone studies insect-borne diseases — particularly those transmitted by ticks and mosquitoes — and is watching closely as the season unfolds.
West Nile virus remains the top concern
While mosquitoes are a global threat in terms of disease transmission, Cassone says Manitobans primarily need to watch out for one illness in particular.
"Here in Manitoba, really the only one we need to worry about from mosquitoes is West Nile virus. And there's active surveillance for it in the province, which is good," he explains.
Environmental factors like temperature, rainfall and humidity directly affect mosquito populations. Warm temperatures help mosquitoes develop faster and seek out hosts. Standing water, often created by rain or human activity, provides perfect breeding grounds.
"Depending on environmental factors you'll get more or less West Nile," Cassone adds. "It usually starts with flu-like symptoms and unfortunately in a small number of cases it can get into your brain and cause encephalitis and induce coma and so forth."
More diseases could be flying under the radar
Another group of mosquito-borne viruses, called the California serogroup (CSG), is also present in Manitoba — though much less is known about their prevalence.
"We don't know a lot about them here," says Cassone. "We think that they are fairly unreported in terms of their infection in the province, but we don't have a lot of information on this."
CSG viruses can cause encephalitis like West Nile, but unlike West Nile, there is no active testing or reporting in Manitoba.
Cassone says both mosquitoes and ticks can carry pathogens that aren't always tested for.
"Lyme Disease from a tick bite moves within you and it's unpredictable in terms of its symptoms, and there are a lot of other diseases that we don't monitor for in our province," he says.
Prevention remains the best protection
With West Nile and other potential illnesses in mind, Cassone urges Manitobans to avoid mosquito bites in the first place. He recommends:
- Wearing insect repellent and light-coloured clothing
- Covering up with long sleeves and pants
- Using bug jackets or hats when needed
- Avoiding outdoor activity at dawn and dusk
- Keeping doors and windows screened
- Spending time in screened-in patios or gazebos
Standing water — even small puddles in containers — is the ideal place for mosquitoes to lay eggs. In warm weather, mosquitoes can grow from egg to adult in just five to seven days.
To reduce risk, residents should drain water from places like:
- Tires, buckets and tarps
- Clogged gutters or downspouts
- Birdbaths and water gardens
- Rain barrels and kiddie pools
"The mosquito that transmits West Nile is the one that lays its eggs in standing water," says Cassone.
If you get bitten and start feeling unwell, he recommends asking your doctor for a blood test — and making sure it’s analyzed at a microbiology lab.
"They generally have a better understanding of tick-borne pathogens and they may be able to help," he says. "That's really the best we can do, unfortunately."
-With files from Betty Sawatzky.