Weather keeping West Nile cases down
Kane County reported its first human case of West Nile virus Wednesday, making it only the fifth county in the state to see a human infection during what's been a down year for the potentially fatal virus.
Kane County's case is a 33-year-old Geneva man. He was treated as an outpatient and is recovering. DuPage County reported its first human case on Monday. The Naperville man, in his 50s, is also recovering. McHenry logged its first human case last week. The Woodstock resident was initially hospitalized, but recovered.
The three recent cases bring the statewide total of human West Nile to 13. That's the lowest total since 2009 when state health officials recorded nine human cases. Last year, there were 117 human cases, including 11 deaths.
West Nile virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird. Most people with the virus have no clinical symptoms of illness, but some might become ill three to 14 days after the bite of an infected mosquito. Only about two of 10 people bitten will experience any illness, which is usually mild and includes fever, headache and body aches, the health department said. Serious illness, such as encephalitis and meningitis, and death are possible.
Because mosquitoes are the transmitter of the disease to humans, weather is a significant factor in the danger levels. The biggest factor in the drop in human cases this year is the mild summer, said Melaney Arnold, a spokeswoman for the Illinois Department of Public Health.
"In hot and dry summers - 2012, 2006 and 2005 - we saw a high level of West Nile virus activity," she said. "In cool and rainy summers, like this one, we see less West Nile virus activity."
Although DuPage, Kane and McHenry counties all reported human cases within days of each other, Arnold indicated recent rains and floods probably are the reason.
"Where there is flooding and a lot of rain, we see what are called floodwater or nuisance mosquitoes, which typically do not carry West Nile virus."
Of the 13 human cases so far this year, eight were male and five were female. More than 61 percent of the victims were between the ages of 45 and 74.