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With COVID-19 and monkeypox making headlines daily, the threat of West Nile virus has receded to the background. But just how much of a risk does West Nile virus pose to Evanstonians?

On July 8, a batch of mosquitoes collected from a trap in Evanston tested positive for the West Nile virus, according to an announcement from the Evanston Health and Human Services Department and the North Shore Mosquito Abatement District. 

Even though the risk of infection and developing a serious case remain low, the consequences of a severe infection from West Nile can be devastating, according to Dr. Vishnu Chundi of Metro Infectious Disease Consultants, which claims to be the largest infectious disease specialty group in the nation.

Unlike COVID-19, the virus follows some kind of “bird-mosquito-human” transmission cycle, according to Chundi. Typically, birds like sparrows and crows are the primary carriers of the virus, and mosquitoes can become infected by biting those birds. Then, the mosquitoes can spread the illness to humans. Humans cannot spread West Nile to other humans, though, which helps limit the number of reported cases each year. 

Usually, people who become infected experience mild, flu-like symptoms such as fever, headache and chills. But, in severe cases, people can get brain inflammation or even become paralyzed, sometimes permanently. 

“It’s such a devastating illness with loss of your normal brain function – the inability to walk can happen, being paralyzed, being on a ventilator or a breathing machine, all of these things can happen because of West Nile,” Chundi said. “So the key is to go out and spray yourself down to prevent the mosquito bite, especially in the morning and in the evening, because that’s when the mosquitoes are most active.”

Using an insect repellent that contains at least 30% DEET, the active ingredient in most bug sprays that repel mosquitoes, can offer up to 99% protection from mosquito-borne illnesses like West Nile, according to Chundi and other experts.

Mosquitoes around Evanston often feed on house sparrows and any small quantities of water they can find. Credit: Pixabay

The mosquitoes in this area tend to feed and reproduce using very small amounts of water, so even a bucket of water or any open container in a yard can pose a risk, Dr. Irfan Hafiz of Northwestern Medicine told the RoundTable. Eliminating any of those small water sources around the home can be crucial in preventing illness because mosquitoes positive for West Nile in Evanston probably mean that a few cases will occur in humans in this region, according to Hafiz.

Public health officials typically report a small number of cases in the Chicago area and across Illinois each year. Evanston, for example, registered one case in 2021 and no cases in the two years before that, the city’s Health and Human Services Director Ike Ogbo said in an email. Statewide there were 64 cases and five deaths in 2021 and 42 cases and four deaths in 2020, according to Ogbo.

“There are effective systems in place to ensure that cases and deaths regarding West Nile Virus are reported efficiently,” he said. “This Department continues to work with the Northshore Mosquito Abatement District in a number of efforts to control the negative impacts of mosquitoes in the area and reduce the risk of diseases from mosquito-borne viruses.”

Still, people often forget to take simple preventive measures, like avoiding bodies of water and using insect spray and wearing loose, long-sleeve clothes, before high-risk activities like hiking, camping or going out for a picnic. When participating in those types of activities, people should spray mosquito repellent over their clothes and any exposed skin, and reapply the spray after sweating or getting wet, especially at sunrise and sunset, the prime feeding hours for mosquitoes.

But any time people in the area are outdoors, like attending a concert at the Ravinia festival in Highland Park, they should be mindful of mosquitoes, particularly given that authorities have identified West Nile in the northern suburbs.

“It’s just crazy not to spray yourself down if you go out to Ravinia because there’s lots of mosquitoes out there,” Chundi said. “There’s great music, there’s nice food, there’s nice people. There’s also not-as-nice mosquitoes.”

You can report flooded yards, standing water or other areas that may produce mosquitoes to the North Shore Mosquito Abatement District by calling 847-446-9434.

Duncan Agnew

Duncan Agnew covers Evanston public schools, affordable housing, City Hall and more for the RoundTable. He also writes long-form investigations, features and the morning email newsletter three times a...

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  1. To correct the record, my husband was diagnosed with West Nile Encephalitis in September 2021 and died on October 6th. I have doubt there were more unreported cases, especially with the intense focus on Covid at the time.