The first reported human case of West Nile in DuPage County this summer is a west suburban man, who would be the third case this year in Illinois.

The DuPage County Health Department announced Thursday the first reported human case of the mosquito-borne virus was a man in his 50s from Glen Ellyn.

The county has seen a “recent increase in mosquito batches testing positive for the presence” of West Nile, which prompted the department to encourage residents to protect themselves from bites and the risk of contracting the illness.

The first confirmed human case in Illinois in 2017 was a man in his 60s from southwest suburban Will County, diagnosed in late June. The second case was a man in his 50s from Bradley in Kankakee County, reported on Aug. 1.

“This is typically the time of year we start to see human cases of West Nile virus in Illinois,” Public Health Director Dr. Nirav Shah said after the first case was confirmed.

Last year, the state’s first human case came earlier, confirmed on June 6, the Illinois Dept. of Public Health said. Overall, 155 human cases were reported, including six deaths.

IDPH says, however, that human cases are often under-reporterd. Last year, 61 counties in Illinois reported a positive mosquito batch, bird and/or human case.

So far this year there have been 10 confirmed cases in birds, and 607 positive mosquito batches, with 41 counties reporting one form of positive test or the other.

Of those, 365 mosquito batches and three birds tested positive in Cook County; while 62 mosquito batches and no birds were positive in DuPage County, IDPH reports. Lake and Will counties each had 19 confirmed mosquito batches, and there was one bird case in Lake.

West Nile virus is transmitted through the bite of a Culex pipiens, or house mosquito. Common symptoms include fever, nausea, headache and muscle aches.