"Fight the Bite": Chicago's Uptick in Mosquitoes

7 days ago

4 min read

Hello Midwest Muse fans! I am finally back from my hiatus, and I feel much more motivated to write. I am also unemployed at the moment, so I have a lot more time to dedicate to producing interesting blogs for you all.

Over the summer, I worked for the Desplaines Valley Mosquito Abatement District (DVMAD) in their laboratory division. It gave me so much experience with lab work, and I got to witness the intersection of ecology, genomics, and public health firsthand. During the season, I collected adult and larval mosquitoes from traps set up around the Desplaines Valley area, identified and recorded their species, and tested adult mosquitoes for West Nile virus and Saint Louis encephalitis using PCR testing. Additionally, we would hunt for ticks to send to the CDC for Lyme disease and alpha-gal syndrome (AGS) testing. I won't bore you with the details of the job, but I will definitely share some photos and videos I took on the job at the end.

The focus of today's blog is West Nile virus, one of the most common diseases you can contract from mosquitoes in America. This summer, there has been a lot of alarming news surrounding mosquitoes and West Nile. First of all, the mosquito breeding season started much earlier this year due to above average temperatures and precipitation in the spring, causing an uptick in mosquito numbers earlier than expected. In turn, West Nile was found in mosquitoes earlier in the season as well. For example, DVMAD's very first test of the season contained positive West Nile results (NOT NORMAL - we expected positive results later in the summer).

Not only did the mosquito breeding season start earlier, but this was the wettest summer in Chicago in a long time. Chicago has almost 10 more inches of rainfall this year than the same time last year (Aug. 31st, 2025 = 22 inches VS Aug. 31st, 2026 = 31 inches)! More rainfall means more standing water which means more mosquito breeding ground.

Total Precipitation in Chicago for 2026 (left) and 2025 (right). Sourced from Global Warming Cities.

The early breeding season and the abundance in breeding pools have also contributed to the increase of the Aedes albopictus (Asian tiger mosquito) which is an invasive mosquito from Eastern Asia. Now, this mosquito is built different. It bites during the day, can breed in little amounts of water, and has a significantly more painful bite. They are also more aggressive than the Culex genus of mosquitoes (most common in the American Midwest). Albopictus can carry West Nile, Zika, dengue, and other diseases. I have seen many people talk about getting mosquito bites much more often this summer than in others, and Aedes albopictus is a big reason why.

Additionally, on September 1, the Chicago Department of Public Health (CDPH) reported Chicago's first death due to West Nile virus of 2026. There have been many reports of West Nile cases in humans across the Chicagoland area, which is becoming concerning to officials. When working for DVMAD, almost every time we ran tests, a positive West Nile result would come up for at least one of the trap sites. This is definitely alarming and something to be mindful of since mosquito density is increasing.

Okay, now a little about West Nile virus itself. West Nile virus is relatively new to the United States, emerging in 1999 in NYC. The first noted appearance in Illinois was in 2001. While most people think of mosquitoes when they think of West Nile, the virus actually originates in birds. Mosquitoes can contract the virus from biting infected birds and then pass it on to humans. WEST NILE CANNOT PASS FROM HUMAN TO HUMAN (which is comforting in some capacity). Horses can also contract West Nile from infected mosquitoes.

What I find very interesting about the history of West Nile in Illinois is the outbreak in 2002. A year after West Nile first emerged, there was a huge West Nile virus outbreak leading to 884 recorded human cases and, sadly, 64 deaths. This was more than any other US state. However, the outbreak was nation-wide with 3,389 human cases in 2002 (compared to 149 total from 1999-2001). I never knew about this outbreak, and I find it very interesting. It's also mysterious that even after that outbreak, there is still no vaccine or treatments for West Nile virus. However, pesticides and larvicides were developed and seem to be working well to control mosquito populations and, in turn, West Niles cases.

The best thing to do to avoid contracting West Nile virus is to avoid getting bit by infected mosquitoes. Wear your bug spray, wear long pants, and drain standing water around your home. It is also comforting to tell you all that most people that contract West Nile do not experience any symptoms or it just simply feels like a cold. It is VERY rare to die from West Nile. Additionally, DVMAD, CDPH, and other public health departments and entities are spraying pesticide around your neighborhoods and applying larvicide to catch basins to control the mosquito populations. I worked with mosquitoes all summer and am just fine, so let that bring you all comfort.

Here are the promised photos from my time at DVMAD!