State health officials say cases of West Nile Virus are at their highest level in at least five years. The mosquitoes that carry the virus flourish is the hot weather that blanketed Minnesota in July. Some of those infected with West Nile don't show symptoms of illness. But if the virus develops into encephalitis it can be fatal.
Severe storms, tornadoes possible in Twin Cities on Thursday
Strong winds, hail and tornadoes are threats in addition to flooding.