Of the 8 new human cases of West Nile virus in the state, 6 are in Cass County.
At least two victims have been hospitalized.
There are now 15 human cases in the state, the counties in red on this map.
Yellow counties have other confirmed West Nile activity.
Cass County's Vector Control Director said he was surprised to see six people on the board so quickly.
Vector Control ramped up its spraying schedule once mosquito numbers jumped last month and the first discovery of the disease carrying mosquito began showing up in traps.
The disease carrying mosquito variety will be around until the first hard frost.