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First WNV Positive Bird For 2004 Found In Michigan
May 11, 2004
Researchers have positively identified the state’s first bird infected with the West Nile Virus (WNV) this year. The crow – found in Saginaw County – was collected on May 5 and tested positive for WNV.
“Because we cannot predict the impact WNV will have on Michigan this year, it is crucial that we continue our efforts with virus surveillance, mosquito control activities, and public education,” said Janet Olszewski, Director of the Michigan Department of Community Health (MDCH). “Citizens need to be aware of the potential risk of WNV infection in Michigan, and communities should use surveillance information to target intervention and prevention strategies in areas where WNV activity has been detected.”
Late spring typically signals the beginning of the season for mosquito-borne diseases such as WNV in Michigan. Surveillance activities for WNV continue this year as a cooperative partnership involving the Michigan Departments of Agriculture, Community Health, Environmental Quality and Natural Resources, Michigan State University, and local health departments throughout the state.
All agencies are integral parts of Michigan’s WNV surveillance, prevention, and response strategies. Mosquitoes most likely to transmit WNV to humans lay eggs in small collections of stagnant water.
Adults can hatch in as short as 10 days time in the warmest months of the summer. Mosquitoes become infected with WNV after feeding on sick birds carrying the virus. Within 10 to 14 days, the mosquito can transmit the virus to humans.
Michigan experienced the second highest number of reported human WNV cases in the nation in 2002. That summer 644 WNV cases – including 51 deaths – were identified in Michigan, and the United States saw the largest WNV epidemic ever reported globally.
WNV continued its westward spread across the continental U.S. in 2003. Michigan was lightly impacted by WNV in 2003, with only 19 human cases and two deaths reported. Nearly 10,000 cases were reported nationwide, with most U.S. cases occurring in the central mountain and plains states.
WNV is expected to continue to spread westward across the U.S. in 2004. Michigan can expect to experience WNV infection in birds, mosquitoes, horses, humans, and other animals in 2004, but the magnitude of the impact cannot be predicted.
“Preventing exposure to mosquitoes in the months ahead will be important,” said Dr. Matthew Boulton, MDCH Chief Medical Executive. “Since West Nile virus is spread to humans and horses almost exclusively through the bite of an infected mosquito, people need to take measures that reduce the chance of receiving mosquito bites. Most people bitten by a WNV infected mosquito show no symptoms of illness. However, some become sick three to 15 days after exposure.
Boulton said about one-in-five infected persons will have mild illness with fever, and about one in 150 infected people will become severely ill. 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.
Persons aged 55 and older are more susceptible to severe WNV diseases. 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.
In a continuing effort to ensure the ongoing safety of the blood supply, in 2003, blood collection agencies nationwide began screening all donated units of blood for WNV. This resulted in very few cases of WNV being acquired through blood transfusion in the U.S. in 2003. Blood donor screening for WNV will continue in 2004.
Michigan residents are encouraged to:
§ Maintain window and door screening to help keep mosquitoes out of buildings.
§ Drain puddles in the yard, emptying water from mosquito breeding sites such as buckets, troughs, barrels, cans, old tires or similar sites where mosquitoes can lay eggs.
§ Avoid being outdoors when mosquitoes are most active (dawn and dusk)
§ Wear light colored long-sleeved shirts and long pants when outdoors.
§ Apply insect repellants that contain the active ingredient DEET to exposed skin or clothing, always following the manufacturer’s directions for use. (Avoid applying repellent to children less than 2 years of age, and to the hands of older children because repellents may be transferred to the eyes or mouth potentially causing irritation or adverse health effects).
Michigan’s interagency WNV cooperative partnership recently completed bird surveillance training for local health departments and animal control agencies and is gearing up to provide information and support to veterinarians and wildlife biologists in an effort to enhance disease surveillance. WNV impacts humans, wild birds and mammals, horses and in some cases, pets.
“Licensed WNV vaccines for horses are available and owners are encouraged to vaccinate, in consultation with private veterinary practitioners,” said Dr. Joan Arnoldi, State Veterinarian. “Horse owners are also encouraged to take preventive measures that will help reduce the risk of mosquito exposure to themselves and their horses.”
Collection of information on the sightings of sick and dead wild birds and mammals is necessary for monitoring the risk of WNV to humans, wildlife and domestic animals. For rapid reporting of a sighting, please use the web-based reporting form by visiting the state's website at www.michigan.gov/westnilevirus.
After submitting your information, you will be advised on how to turn in an animal for laboratory testing, if it is needed. This website also contains updated information on WNV, how to participate in the Michigan surveillance efforts, and to view maps and tables containing data on West Nile cases in humans, birds, horses and mosquitoes in Michigan
For those without Internet access, you may use your local library to access the Internet or call the statewide toll-free number at: 1-888-668-0869 for updated information about WNV.
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