State's First Probable Human Case of West Nile Virus Reported

MACOMB COUNTY HEALTH DEPARTMENT:
Sue Tremonti
(586) 783-8161
Sherry LaBelle
(586) 469-5236

Michigan health officials have identified a Macomb County man as the state's first probable human case of West Nile Virus (WNV) for 2011. The 48-year-old man was hospitalized earlier this month after showing symptoms in early August. He has since died. Confirmatory testing is pending at the Michigan Department of Community Health's Bureau of Laboratories.

Ecologic testing conducted at Michigan State University has detected WNV in a Saginaw County crow that was found dead Aug. 16. Mosquito pools from Saginaw County collected in early August also recently tested positive for WNV. Mosquito testing is ongoing, but preliminary results indicate infected mosquitoes in Bay County as well.

High temperatures and heavy rainfalls this summer have contributed to an increase in overall mosquito populations.

"West Nile Virus is a very serious disease," said Dr. Dean Sienko, Interim Chief Medical Executive. "It's important that residents understand the risks associated with West Nile Virus and take the appropriate precautions to avoid getting infected."

Dr. Kevin Lokar, Medical Director for Macomb County Health Department, said West Nile Virus is not uncommon in Macomb County.

"In 2010 we had 11 confirmed cases of WNV, including three deaths," he said. "Although most of these people were in their 60s or 70s, the youngest was in her 20s. All 11 lived in the more urbanized, densely-populated part of the county."

The months of August and September are when most human cases of West Nile Virus occur in Michigan. The end of summer is when mosquitoes are older and more likely to carry the virus. The types of mosquitoes that transmit the virus bite during evening and nighttime hours.

Most people bitten by a WNV infected mosquito show no symptoms of illness. However, some become sick three to 15 days after exposure.

About one-in-five infected persons will have mild illness with fever. About one in 150 infected people will become severely ill. Those illnesses include encephalitis and meningitis. Symptoms of encephalitis (inflammation of the brain) and meningitis (inflammation of the spinal cord and brain linings) include stiff neck, stupor, disorientation, coma, tremors, muscle weakness, convulsions and paralysis.

People 55 and older are more susceptible to severe WNV disease symptoms. Physicians are urged to test patients for WNV if they present with fever and signs of meningitis or encephalitis, or sudden painless paralysis in the absence of stroke in the summer months.

Since its arrival in Michigan in 2001, WNV has caused at least 860 human cases and 71 deaths. In 2010, Michigan reported 29 cases of WNV, including three deaths. In addition, three other mosquito-borne viruses caused human illness in the state including Eastern Equine Encephalitis (EEE), St. Louis encephalitis (SLE), and La Crosse encephalitis (LAC) virus. Southeast Michigan is a recurrent focus of WNV activity annually.

Michigan residents are encouraged to take the following steps to avoid WNV:

• Maintain window and door screening to help keep mosquitoes out of buildings.
• Empty water from mosquito breeding sites such as buckets, unused kiddie pools, old tires or similar sites where mosquitoes lay eggs.
• Avoid being outdoors at dusk and dawn when mosquitoes are most active.
• Wear light colored, long-sleeved shirts and long pants when outdoors.
• Apply insect repellents that contain the active ingredient DEET, or other EPA approved repellent to exposed skin or clothing, always following the manufacturer's directions for use.

For more information and surveillance activity updates about West Nile virus, visit the state's Emerging Diseases website at www.michigan.gov/westnilevirus.