In the more than 20 years since West Nile virus established itself in North America, local, county and state organizations have built robust systems to monitor and abate mosquitoes that carry it.
Mosquitoes carrying the virus were found in Medinah, Wheaton and Wood Dale July 5, the first in DuPage County to test positive this year. • Defend: When outdoors, use an insect repellent containing DEET, picaridin, oil of lemon eucalyptus, 2-undecanone or IR3535 and reapply according to label directions.
"Climate is just one of many important factors that influence the transmission, distribution and incidence of West Nile virus disease," according to the U.S. Environmental Protection Agency.
Irwin, who has been studying mosquitoes as an entomologist for nearly two decades, tests the district's 40 mosquito traps daily for West Nile virus. Because the virus has been in Illinois for a relatively short time -- it was first detected in the state in September 2001 -- Irwin hopes outbreaks will become more predictable as data builds.