All the cases so far have been in birds or pools of mosquitoes. No humans in Illinois have been infected so far this year.
The state Department of Public Health says 27 birds in 17 Illinois counties have died of West Nile this year. Another 13 pools of mosquitoes, ten of them in DuPage County, have tested positive for the virus.
On June 1, only five birds had tested positive. Health Department spokesman Tom Schafer says the numbers are not surprising, but he says officials don't know yet whether the state will see a major outbreak of the mosquito-borne disease this summer.
The mosquitoes that most often carry West Nile are most active in hot, dry weather.
West Nile in Illinois
- In Illinois, West Nile virus was first identified in September 2001 when laboratory tests confirmed its presence in two dead crows found in the Chicago metropolitan area.
- Since then, more than 100 birds, mosquitoes and horses in seven counties -- six in the Chicago area and Crawford County in central Illinois -- have tested positive for the virus.
- The Illinois Department of Public Health (IDPH) has had a sophisticated disease surveillance system in place since 2000 to monitor animals and insects that can potentially carry the virus: wild birds; dead crows, blue jays and raptors; and mosquitoes.
- Over the past two years, the virus, which can be transmitted to humans by the bite of an infected mosquito, has quickly spread throughout the northeastern states and to states south and west of New York.
- In 2001, West Nile virus was also identified in other Midwestern states, including Indiana, Iowa, Kentucky, Missouri and Wisconsin.
States With Birds Testing Positive in 2002:
- District of Columbia
- New York
- New Jersey
- North Carolina
Source: http://www.idph.state.il.us/envhealth/wnv.htm (Illinois Department of Health Web site), and http://westnilevirus.nbii.gov/ (National Biological Information Infrastructure Web site) contributed to this report.