State health officials said Thursday they have identified the first case of West Nile virus this year.

It was contracted by an adult in the Baltimore metropolitan area, according to the Department of Health and Mental Hygiene.

Most people who come in contact with the disease show no symptoms, but in rare instances it can cause death.

The number of humans with the disease in Maryland has varied widely over the past several years. Seventy-three human cases were reported in the peak year of 2003. Only one confirmed case was identified in 2009 and last year 23 people contracted the disease.

The disease has also recently been detected in mosquitoes and birds in Maryland. Three pools of mosquitoes collected in Montgomery County by the U.S. Department of Defense tested positive for West Nile. A mosquito pool is a group of mosquitoes collected at sites across the state.

Three sick birds from a Montgomery County wildlife center also recently tested positive for the disease.

Symptoms of West Nile include fever, headache, body aches, skin rash and swollen lymph glands. Symptoms generally appear three to 15 days after a mosquito bite.

Less than one percent of persons exposed to the virus will develop more severe infections with symptoms such as headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

People over age 50 and those who are immunocompromised have the highest risk of developing more severe disease.

State officials said people can take precautions to prevent the disease including, avoiding areas of high mosquito infestation and limiting outdoor activities at dawn and dusk when mosquitoes are most active. Also, wear long pants, long-sleeved shirts and hats when concerned about mosquito exposure and use mosquito repellants according to directions.

Residents should also monitor their own yards and gardens for standing water that can serve as a breeding ground for mosquitoes. As little as one-half inch of water in a discarded can or container will support dozens of mosquitoes.

Sick or injured birds can be reported to local wildlife rehabilitators.