Mosquitoes infected with West Nile virus have landed in Evanston, Skokie, Kenilworth and Glenview, officials say.
Batches of mosquitoes collected Wednesday in traps set in the communities by the North Shore Mosquito Abatement District tested positive for the disease, according to a press release issued by the city. Mosquitoes infected with the virus have also been caught in NSMAD traps in Skokie, Kenilworth and Glenview.
The virus has been a part of public health discussions since it first arrived in the United States in New York in 2001, said Evanston's assistant director of health and human services, Carl Caneva. In a typical year, he said, NSMAD traps mosquitoes that test positive for the virus around the end of June, birds carrying the virus are usually found later on in the season, while human infections are reported usually toward the end of summer.
"All residents in Illinois are at risk of contracting West Nile virus from mosquito bites. West Nile Virus infection can lead to serious health effects," said Skokie's director of health, Catherine Counard, in an email.
According to the Centers for Disease Control and Prevention, 70 to 80 percent of humans infected with the virus do not development any symptoms. Those who do experience symptoms ranging from fever to headaches, body aches, joint pains, diarrhea, vomiting and rash, according to the CDC's website, and fewer than one percent of people who contract the virus will develop inflammation of the brain or surrounding tissue.
Caneva said individuals age 50 and older and those with chronic health issues are at the greatest risk of serious complications from West Nile virus, including paralysis and death.
"It's important that people are vigilant in protecting themselves and making sure they are not producing mosquitoes on their property, limiting stagnant water, not leaving dog bowls with water out, or allowing water to pond on their property," he said.
If it can hold water, "mosquitoes can breed in it," Counard wrote.
Both Counard and Caneva recommend residents stay indoors during peak biting times -- the hours of dawn and dusk -- wear loose fitting long-sleeved shirts and pants and use insect repellent while outside.
Caneva said NSMAD injects larvicide into storm sewers to prevent mosquitoes from maturing in those areas. When high percentages of trapped mosquitoes test positive for the virus, the district will also spray in areas where adult mosquito populations congregate.
The level of West Nile virus generally depends on the weather, he said.
"It can be very misleading because a lot of people think if we have flooding and lots of rain we'll have a big West Nile virus problem," Caneva said. He said it doesn't take much water for mosquitoes to breed and it's high temperatures that accelerates the time it takes for the insects to transition from the larva to adult life stage.
The National Oceanic and Atmospheric Administration has predicted a hotter than normal summer for most of the country. The first human case of West Nile virus in "west-central Illinois" this year was discovered in late May when a teenager exhibited symptoms of the virus, according to the state's Department of Public Health.
Caneva said the incident is atypical given that human cases are generally reported later in the season.
"That is not indicative that this is going to be a bad summer or a summer with a lot of issues, but that is a littler bit concerning because there is a schedule of how things happen," he said.
Residents are encouraged to contact NSMAD to report stagnant water in roadside ditches, flooded yards or other locations that may breed mosquitoes via email at firstname.lastname@example.org or call 847-446-9434.
Lee V. Gaines is a freelance reporter for Pioneer Press.