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Chicago Mosquitoes Could Ruin Your Life, But Probably Not With Zika Virus

By Marielle Shaw in News on Mar 2, 2016 10:02PM

Alexandra Westrich holding a specimen. Photo courtesy of The Field Museum, taken by James Waters

As the mosquito-borne Zika virus spreads through South America, a Chicago hospital confirmed the first local case of the virus Tuesday: A 30-year-old woman tested positive for the disease after returning from a trip to Colombia in January. She has made a full recovery, and the virus is not expected to spread through the city.

We still had questions, though, so we spoke with the Field Museum's Alexandra Westrich, a mosquito expert and research assistant who works with the Chicago Department of Public Health on the West Nile Virus Surveillance Team. We asked her what was important to know about the Zika virus and the mosquitoes in our area.

The mosquitoes that carry the Zika virus originate from the genus Aedes, Westrich explained. But while Chicago is home to some species from the Aedes family, Chicagoans aren't at risk of catching the virus from a local mosquito—the two specific types of mosquitoes that carry the virus aren't present here.

"It's only a matter of how many people here are traveling and bringing it back," she said. This makes transmission, and certainly an epidemic, extremely unlikely in Illinois, as cases of Zika must be "imported."

Compared to the West Nile Virus, Zika is less of a concern for Chicagoans, she added—both in severity, since West Nile's encephalitic form can be fatal, and in its reach, since at least some of the mosquito pools in Chicago test positive for West Nile every year.

Zika is only now considered a health concern, Westrich says, because of its implications for pregnant women.

"It is a significant public health concern because of the link to the birth defects, but it hasn't caused any fatalities yet," she said. She advocates "minimizing the alarmism" and instead "waiting until more concrete evidence of the causative agents has come in."

If you are concerned about Zika or West Nile, Westrich's recommendation is to stay informed about mosquito ecology—which means, among other things, avoiding standing water.

"Mosquitoes have an aquatic larval stage and lay their eggs in standing water, or containers that can fill with water when it rains," she said. "If you're in an area where there are a lot of mosquitoes, use repellent. And finally, if you do spot areas of standing water, dead birds, or tall weeds, you can report this to 311 so that something can be done."

So to sum up: No need to panic here in Chicago, but as usual, take precautions to avoid exposure to the nasty little buggers once spring arrives.