West Nile Virus Testing Update

The Michigan Department of Community Health and the Michigan Department of Agriculture today provided a West Nile virus testing update. Ongoing public health surveillance for the virus has not detected any cases of West Nile virus in humans in Michigan.

The West Nile virus has been detected in 44 crows and one blue jay found in Wayne, Oakland, Macomb, Ingham, Jackson, Washtenaw, Barry and Calhoun counties. Due to the laboratory confirmation of the virus in these counties, birds will no longer need to be submitted for testing from these eight counties. However, reports of dead crows from these counties should continue to be called in to the state's West Nile virus toll-free hotline at 888-668-0869 or to local health departments.

Residents who find a dead crow or blue jay should contact their local health officials or report them to the toll-free hotline. Only black crow and blue jay specimens, from counties other than Wayne, Oakland, Macomb, Ingham, Jackson, Washtenaw, Barry and Calhoun, should be submitted for testing. Decomposed or mutilated birds should not be submitted as they cannot be tested.

Mosquito surveillance for West Nile virus has been underway in areas where infected birds have been found. Testing on these trapped mosquitoes has identified West Nile virus in a sample of mosquitoes in Oakland county and a sample of mosquitoes from Macomb county. These positive mosquitoes were of the Culex pipiens species, which almost exclusively bite only birds. The testing on mosquito species that bite both horses and humans as well as birds, the so called "cross-over" species, has been negative to date.

Mosquito trapping and testing is coming to a close for this season. State and local officials will continue to plan both bird and mosquito surveillance for next year.

"While mosquito activity appears to be relatively light right now, it is still a good idea to take precautions to avoid mosquito bites," said Michigan Department of Community Health Chief Medical Executive, Dr. David Johnson. "This is especially true for older individuals who are at higher risk for West Nile encephalitis."

Mosquitoes become infected with West Nile virus when they feed on infected birds that carry the virus in their blood. After 10 to 14 days, the mosquitos salivary glands become
infected and those infected mosquitoes can then transmit the virus to humans and other animals while biting them to take blood. During blood feeding, the mosquito injects the virus into the animal or human, where it multiplies and may cause illness. Most crows are very susceptible to infection with West Nile virus and will die within two to three weeks of infection.

Most people infected with the West Nile virus have no symptoms of illness, but some may become ill three to 15 days after the bite of an infected mosquito. Based on preliminary evidence, about one in four infected persons will have mild illness with fever, headache and body aches, sometimes with skin rash and swollen lymph glands. Encephalitis is less common and may include headache, high fever, stiff neck, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. In a few cases, mostly among the elderly, death may occur.

The virus is NOT transmitted from person-to-person. You cannot get it from touching or kissing a person who has the virus or from a health care worker who has treated someone with it.

While there is no human vaccine for West Nile encephalitis, there are many ways to reduce the risk of becoming infected. They include:
-- Apply insect repellent that contains the active ingredient DEET to exposed skin. Follow the manufacturer's directions for use on the label.
-- Spray clothing with repellents containing permethrin or DEET because mosquitoes may bite through thin clothing. Follow the manufacturer's directions for use on the label.
-- Avoid applying repellent to children under 2 years of age, and to the hands of older children because repellents may irritate the eyes and mouth.
-- Maintain window and door screening to keep mosquitoes out of buildings.
-- Drain standing water in the yard. Empty water from mosquito breeding sites, such as flower pots, pet bowls, clogged rain gutters, swimming pool covers, discarded tires, buckets, barrels, cans and similar sites in which mosquitoes can lay eggs.
-- Wear long-sleeved shirts and long pants when outdoors.

Horse owners in areas where West Nile virus has been detected are encouraged to contact their local veterinarian to discuss appropriate preventive measures.

Prevention tips for horses include:
-- Use approved insect repellants to protect horses,
-- Put horses in stables, stalls or barn during the prime mosquito exposure hours of dawn and dusk, if possible.
-- Eliminate standing water and drain troughs and buckets at least two times a week.

Information on West Nile virus can be found on the Department of Agriculture website at http://www.mda.state.mi.us, the Department of Community Health website at http://www.mdch.state.mi.us or the CDC website at http://www.cdc.gov.