While everyone is enjoying the summer months, they should remember to protect against mosquitoes while outside.
© Submitted photo
This map, provided on the Ministry of Health website, shows the risk areas for West Nile virus in different parts of Saskatchewan. The map will be updated weekly on the government website.
Although most mosquitoes are little more than a nuisance, one species can carry the West Nile virus.
“With all the rains we have had in June and late June, we are seeing an emergence of higher than normal mosquitoes of many different species,” said Phil Curry, a consultant for the West Nile Virus Provincial Control program. “We haven’t seen these levels for quite a few years.”
The mosquito most commonly found at this time of summer is the Aedes vexan, which does not carry the virus, Curry said.
“It is a very common summer nuisance mosquito,” he said. “It likes biting people and it is very annoying.”
Culex tarsalis is the mosquito to watch out for, he said, since is does carry the West Nile virus.
“We have recorded it in small numbers throughout southern Saskatchewan and we are expecting that their numbers are going to increase over the next few weeks,” Curry said. “This mosquito can have many generations and it comes out in low numbers in the spring and gradually builds up its numbers throughout the summer.”
This species usually reaches its peak at the end of July and into the first week in August.
“We have not have any positive or infected mosquitoes to date, however, with these warm temperatures, these conditions are optimal for not only the activity of the mosquito but for it to bite birds and up the virus,” Curry said. “We should see an increasing risk of West Nile in the coming weeks.”
Luckily, the Prince Albert area is at a lower risk of having a lot of the Culex tarsalis species of mosquito, since it prefers a prairie or grassland environment.
“We know that the habitat for the mosquito only occurs in certain parts of the province so this mosquito doesn’t like the north because this is a forested region and generally we don’t find that mosquito up north,” said Dr. Denise Werker, deputy chief medical health officer for the province. “The higher risk areas in general are the areas in the south, which are the agricultural areas that are habitats for the type of mosquito that carries the West Nile virus.”
The West Nile virus was first introduced in North America in 1999 in New York City, Werker said. It soon spread to Canada and by 2005 it was well-established in mosquito populations.
“With a new disease, there was a lot of effort to understand what that disease looked like in humans,” Werker said. “Ten years later, we have now said we need to rethink what kind of information we need to gather and what kind of communications we need to tell people to prevent this disease.”
This year, the province is changing the focus from human cases of the virus to the mosquito.
“In order to prevent and control West Nile virus, people need to be aware of the risk and the risk is in the mosquitoes,” Werker said. “West Nile virus is not transmitted from person to person, so the focus on the cases doesn’t make sense.
“People need to be aware of what the situation is on the mosquitoes when the concentration (of the infected) mosquitoes increase,” she added. “We have a number of environmental indicators that help us establish what the level of risk is for transmission to humans.”
She said if they focus on human cases, they will miss the opportunity to prevent and control the disease.
“The problem with this disease is it happens the reporting of that to professionals can happen weeks after the risk, the transmission risk, in the mosquitoes has occurred,” Werker said. “If we focus on the neuroinvasive cases, we basically miss the boat. We are not telling the people to pay attention to the risk when the risk has occurred.”
Although the virus can have neuroinvasive symptoms, about 80 per cent of the population will be asymptomatic or just have a mild infection and will not have to seek medical care.
Anyone who shows symptoms such as a severe headache, neck pain, high fever or signs of paralysis should seek medical attention.
“These can be very serious infections and sometimes require support in intensive care unit,” Werker said. “We do want to make sure that clinicians appropriately diagnose these cases so people can get appropriate care.”
Information on West Nile Virus is available at www.health.gov.sk.ca/west-nile-virus. The page will be updated weekly to show the risk areas in the province.
“Rather than focus on individual health regions, we are looking at the whole ecological risk area,” Curry said. “If you get bitten by a mosquito in Regina and it is Culex tarsalis, Culex tarsalis is widespread throughout the southern part of the province so the risk, whether you are in southwest or southeast will be relativity the same.”
Curry and Werker suggest wearing an insect repellant with DEET and wearing long sleeves and long pants while going outside to reduce the risk of West Nile virus.
“The mosquito that carries the West Nile virus tends to be more active in the evening as opposed to the one that is out right now which is biting during the day,” Curry said. “In the evening, wear long sleeves, bring a sweater with you, just cover up.”