Illinois health officials announced they have confirmed the first human cases of West Nile Virus in 2011, a condition that is spread through mosquito bites and can in some cases cause fatal diseases.

The first human case was reported in July after a man in his 30s from Marion became ill. Moreover, a man in his 80s from Palatine was also infected in early August, according to the Illinois Department of Public Health, which said the man is recovering in a hospital.

West Nile virus activity in mosquitoes and birds continues to increase across Illinois, which means a higher risk of people contracting the virus, state Public Health Director Dr. Damon Arnold said in a release from the department.

Arnold said people should wear insect repellent and get rid of any standing water near their homes to protect themselves from mosquitoes.

Last year, U.S. health officials reported a total of 61 human cases of West Nile. The first case was reported on Aug. 31.

West Nile is transmitted through the bite of a mosquito that contracted the virus from feeding on an infected bird. Although the Centers for Disease Control and Prevention reports that most people who are bitten by infected mosquitoes have so clinical symptoms of illness, others may become sick within three to 14 days.

About one in 150 people infected with West Nile Virus will develop severe illness, symptoms of which may include neck stiffness, tremors, coma, convulsions, vision loss, numbness and paralysis. Symptom can last several weeks and the neurological impacts may be permanent, the CDC reports.

Older adults should take extra precautions to avoid mosquito bites, as individuals over the age of 50 are more likely to develop serious symptoms of West Nile Virus if infected.