More than 350 million people are chronically infected with the virus that causes severe liver damage and many kinds of health problems including liver cancer and death.
Dr. Adrian Bisceglie says practical applications could include identifying emerging viruses or combating terrorism.
The human cases have been reported in Chicago, Evanston and several Chicago suburbs.
Tainted bugs have turned up in No. County, Normandy, Olivette, Jennings, elsewhere.
The county health department says the 12 year-old boy was hospitalized briefly.
Mosquitoes with West Nile have been found in communities ranging from Lemay in the southern part of the county to Florissant.
As weather warms, such sites provide perfect breeding ground for mosquitoes, West Nile virus.