A group of researchers from Brock University are sounding the alarm about a predicted influx of West Nile cases in Ontario this summer.

Brad Giordano, PhD candidate and lead researcher on the study, told CTV News Channel that after surveilling “decades worth” of mosquito data from Ontario, as well as data from human cases, they predict a looming “epidemic” of infections.

“Our positive mosquito numbers are still ramping up,” he said.

Since the virus first arrived in Canada back in 2001, the province has been surveilling mosquito populations through a weekly trapping system. The program starts in May and lasts through to October.

Each week, the traps are collected and sent to certified laboratories where the mosquitoes are separated by species and tested for the presence of West Nile.

“We’re at about week 33 here and we have approximately 250 mosquito pools that have tested positive for West Nile virus. When we throw that number into our prediction model, this comes up with approximately 500 human cases that we could have by the end of the season. So that’s not right now – because typically what we see, once someone becomes infected, they may not show symptoms at all.”

He said 80 per cent of people infected don’t show symptoms at all.

Back in 2002, when the infection rate was at its peak, Giordano said Ontario saw approximately 500 human cases of the West Nile Virus. In the second recorded outbreak in 2012, that number sat around 250.

“We’re ramping up to be somewhere in between 2002 and 2012 (this year),” he said.

While it’s too early to predict when exactly Ontario will see a peak this summer, Giordano said the number of positive mosquito traps are rising every week.

“It really depends on what are numbers are going to be like next week,” he said. “If our positive mosquito pools are still ramping up, so we still haven’t hit that peak yet, then we are unable right now to estimate when the peak number of human cases will occur.”

Public health officials in several southern Ontario regions have already warned residents about the presence of the virus this summer alone.

Toronto, Mississauga and the Toronto Islands all had mosquitoes trap test positive for the virus.

Toronto’s associate medical officer of health says the city has been monitoring its mosquito surveillance program closely and also taking a number of preventative measures.

“We prepare for an epidemic by doing our mosquito surveillance, so looking at how many mosquitoes we have and what’s the infection rate for West Nile Virus,” Dr. Christine Navarro told CP24 on Wednesday. “We look at human surveillance as well we larvicide across the city and have 120,000 catch basins. We also educate people on our website and through social media.”

According to Toronto Public Health, 31 mosquito traps tested positive in the city since August 16.

But de Navarro says that, so far, those results are lower than years past.

“In Toronto, based on our mosquito surveillance, we have had fewer positive pools of mosquitoes and we have had lower mosquito infection rates in Toronto so far,” Navarro told CP24 on Wednesday.

“But that can change, so it is important for people to take precaution when they’re spending time outdoors.”

Although the risk of catching the virus is relatively low, health officials previously said that this year’s unusually wet weather has created ideal breeding grounds for mosquitoes.

Residents can reduce potential exposure to the virus by wearing light coloured, long-sleeved clothing and use an insect repellant.

Public health officials also encourage residents to take special caution during hot weather – during dusk and dawn – when mosquitoes are said to be the most active.

Thus far, there have been no confirmed human cases of the virus reported in Ontario this year.

With files from CTV News