CHICAGO (FOX 32 News) - The alert level for West Nile virus has been moved up a notch in Chicago’s North Shore suburbs. The number of mosquitos carrying the virus has doubled in the past week.
Culex Pipiens is one of several mosquito species bugging the Chicago area right now. But its bite is more than a nuisance, because it carries the potentially dangerous West Nile virus.
"It has increased over the last several weeks,” said Dave Zazra of North Shore Mosquito Abatement District.
Zazra says they found mosquitos carrying West Nile in 97 traps last week, compared to 49 the week before, which prompted them to raise the West Nile risk status from minimal to moderate.
"They like to breed in very stagnant water sources, whether it's the stormwater catchbasins or containers in your yard,” Zazra said.
FOX 32 watched as they tested a fresh batch of mosquitos, dumping the dead insects into vials, adding a liquid chemical and then shaking them into something of a mosquito puree.
"A liquefied mosquito sample which we'll later place into a cartridge after centrifuging and run through a machine that will test how much viral content is in each sample,” said District Biologist Chris Xamplas.
FOX 32 also watched as abatement crews dropped pellets of Larvacide in catchbasins and storm sewers, which is the areas where the Curex mosquitos breed.
Mosquitos with West Nile have been found in 12 of the 14 north shore suburbs served by the district over a 70 square mile area.
"It's not at the level it was in 2012, the last time we had an outbbreak, where we had 20 cases of West Nile Virus diagnosed in the district. But we're above our background levels and that's what we're concerned about,” said District Executive Director Dr. Roger Nasci.
And mosquito experts say those heavy rains that deluged the Chicago area over the weekend will be both a blessing and a curse. That’s because the rain flushed out the stagnant water favored by the Culex mosquito, suppressing West Nile. But it also hatched billions of floodwater mosquitos that don't carry the disease, but will be very hungry.
"Those eggs can survive over a few winters. So eggs that may have been laid a couple summers ago, this excessive rain covering that up is gonna cause a big hatch,” Zazra said.