The Centers for Disease Control is reporting 4 cases of West Nile in Minnesota so far this year.
 
 In all four of those cases, the CDC says the disease was found following blood donations.
Officials say the infected people had no symptoms at the time of donating blood through a blood collection agency, but tested positive for West Nile when they were screened for the disease.
Peak season for West Nile in Minnesota is mid-July through mid-September.
The Minnesota Department of Health says most people who have West Nile will experience flu-like symptoms.
It was first detected in Minnesota in 2002.