MONTCALM COUNTY, Mich. (WOOD) — Two people from Montcalm County are among the first Michigan residents confirmed to have West Nile virus this year, health officials say.

The Michigan Department of Health and Human Services said it has confirmed a total of four cases of West Nile virus in humans this year. The two others sickened by West Nile virus were from Oakland and Macomb counties.

Health officials say all four people were sickened between Aug. 6 and Aug. 11. All of them were hospitalized; some of them were still in the hospital, as of Aug. 31, according to health department spokesperson Angela Minicuci.

She told 24 Hour News 8 the patients range in age from 35 years to 70 years. Three of those sickened were men, the other was a woman.

Health officials say tests also detected the virus in the blood of five Michigan blood donors this year.

Health officials say West Nile virus activity this year appears to be widespread across Michigan.

So far, 148 birds in 44 Michigan counties have tested positive for the mosquito-borne virus. MDHHS says 86 mosquito pools in seven Michigan counties also came back positive for West Nile virus.

Horses are also susceptible. The Michigan Department of Agriculture and Rural Development says West Nile virus was confirmed in eight horses, including at least one in Ottawa County.

Dr. Eden Wells of the MDHHS says the cases serve as an important reminder to take all necessary precautions to avoid

mosquito bites, including wearing repellent and avoiding peak mosquito-biting hours.

While most people sickened by West Nile virus do not develop any symptoms, health officials say about 20 percent suffer mild illness with fever and about 1 in 150 people become severely ill.

Mild symptoms may include headache, body aches, joint pain, vomiting, diarrhea, or rash. Severe symptoms of West Nile virus are associated with encephalitis or meningitis, and may include stiff neck, stupor, disorientation, coma, tremors, muscle weakness, convulsions and paralysis.