Thursday, May 03, 2018

Illinois Among Top States for Mosquito-bite Diseases: CDC
Illinois saw the number of mosquito- and tick-borne diseases jump from 226 in 2004 to 772 in 2016, according to CDC data. (James Gathany / AP)

Elyssa Cherney
Chicago Tribune

The Centers for Disease Control and Prevention is warning about a rise in insect-borne diseases — and Illinois is right up there, ranking sixth among states with the most mosquito-related illnesses.

Between 2004 and 2016 nationwide, diseases from mosquito, tick and flea bites tripled to more than 640,000 cases, according to the study released Tuesday.

Illinois saw the number of mosquito- and tick-borne diseases jump from 226 in 2004 to 772 in 2016, according to CDC data. Data for flea-borne illness couldn’t be located for those individual years.

Examining mosquito-related diseases alone, such as West Nile virus, Illinois logged more than 2,580 such cases during that 13-year stretch, according to the report. That’s behind only Colorado, Florida, New York, Texas and California, which had the most cases — 9,254. Except for Colorado, the states with more cases than Illinois are also more populous, according to the U.S. Census Bureau.

The rise in mosquito-transmitted diseases nationwide is likely related to the spike in West Nile virus, which hit Illinois particularly hard starting in 2002, said Chris Stone, who studies mosquitoes for the Illinois Natural History Survey.

“Illinois was just one of the major states where the West Nile epidemic had a peak, and it continues to be quite prevalent,” Stone said. “In part, that must be due to the Chicago area airports being so large and having lots of imported cases.”

Urban centers filled with retention ponds and storm drains that hold sitting water for a period of time can also create an environment that nurtures mosquitoes, Stone said.

Nationwide, the CDC report found the U.S. is vulnerable for another epidemic if it does not improve its local and state health departments to control mosquito and tick populations. The report also found that nine new germs spread by mosquitoes and ticks have been discovered or introduced since 2004. The report was conducted by analyzing data from the National Notifiable Diseases Surveillance System, which is also run by the CDC, for 16 types of insect-borne illnesses.

Here are the five takeaways from the study, including how to protect yourself this summer:

1. West Nile virus is the top mosquito-borne disease in Illinois, the report said. At its height, Illinois led the nation in the disease in 2002 with 884 diagnoses and 67 deaths, according to the Illinois Department of Public Health. Last year there were 89 cases of West Nile in 80 different counties, the health department said. West Nile virus, which is carried by the Asian tiger mosquito, is especially dangerous for people older than 50 or those with weak immune systems. It causes flu-like symptoms and can lead to death in some cases.

2. The most common type of tick-borne illnesses was Lyme disease, the report said. In the time period examined by the CDC, 352 cases of Lyme disease were reported. The most common type of biting ticks in Illinois are the American dog tick and the lone star tick.

3. Most mosquito bites in Illinois don’t come from the bug that carries West Nile. The most ubiquitous biting insect in Illinois is the Indian floodwater mosquito, which rarely transmits any diseases, according to the Illinois Department of Public Health. These mosquitoes lay their eggs in soil that is flooded and are particularly active along riverbanks and other low-lying places.

4. It’s unlikely you will contract the Zika virus from a bug bite in Illinois, according to the health department. In 2017 there were eight cases of Zika among Illinois blood donors who did not experience any symptoms, according to the CDC. Those cases were related to people who traveled to areas where the virus was prevalent. Zika, which poses extreme problems for pregnant women, has not been transmitted through bug bites in the state.

5. To ward off mosquitoes and ticks, choose an insect repellent with DEET, Stone said. DEET doesn’t kill insects, but it works by making it harder for them to identify the human scent, according to the federal Environmental Protection Agency, which has found the product safe to use.

echerney@chicagotribune.com

Twitter @elyssacherney

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