Human West Nile Virus Cases on the Rise

Michigan health officials are reporting that a Washtenaw County woman who was hospitalized with viral meningitis is the state’s first human West Nile Virus death this year.

The previously healthy woman who was between the ages of 75 and 85 was hospitalized at the beginning of August after showing symptoms commonly associated with the virus.

“With the virus appearing earlier this year than it has in recent years, we want to remind residents to take the appropriate precautions to avoid getting bitten,” said Dr. Corinne Miller, state epidemiologist with the Michigan Department of Community Health.

Human West Nile Virus cases are on the rise both nationally and in Michigan. Thus far in 2012, a total of 693 cases of West Nile Virus disease in people, including 26 deaths, have been reported to the Center for Disease Control. Miller said this is the highest number of cases reported to the CDC through the second week in August since 1999, when the virus was first detected in the United States.

For Michigan, a total of 24 cases and one death have been reported for the same time period. Those infected range in age from 18 to 84, with the average being 55. The virus appeared in birds and mosquitoes in Michigan in 2001 and in humans in 2002. This is the highest number of human cases reported for Michigan through the second week of August since 2002.

Last year, West Nile Virus was responsible for 34 serious illnesses and two fatalities in Michigan.

“The unusually hot and dry summer has favored the mosquitoes that transmit West Nile Virus. These same conditions have led to a reduction in the number of 'nuisance' mosquitoes which are more abundant during wet summers, giving citizens a false sense of security,” Miller said.

Mosquitoes breed in small collections of stagnant water, are common around people’s homes and often bite people indoors. While few mosquitoes may be noticed outdoors, those that are present and biting are likely to be the type that potentially carry the virus.

The months of August and September are when most human cases of West Nile 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 night time hours.

Most people bitten by an infected mosquito show no symptoms of illness. However, some become sick three to 15 days after exposure. People 50 and older are more susceptible to severe disease symptoms.

Michigan residents are encouraged to take the following steps to avoid West Nile Virus:

• 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.
• Apply insect repellents that contain the active ingredient DEET, or other EPA approved repellent to exposed skin or clothing, especially during peak mosquito activity periods such as dusk and dawn.
• Wear light colored, long-sleeved shirts and long pants when outdoors.

For more information, visit the state's emerging diseases website at www.michigan.gov/westnilevirus or the CDC’s website at www.cdc.gov/ncidod/dvbid/westnile/index.htm.