Officials with the Michigan Department of Agriculture and Rural Development and Michigan State University Diagnostic Center for Population and Animal Health confirmed the first West Nile case of the year in an unvaccinated Montcalm County horse due to West Nile Virus infection.
The five-year-old Standardbred gelding developed sudden incoordination in the hind limbs and is currently undergoing treatment (supportive care) for West Nile Virus.
Officials also reported the state has had its first death from the West Nile virus, an elderly woman in Washtenaw County.
The Michigan Department of Community Health isn't identifying the woman, saying only that she was 75 to 85 years old and was hospitalized earlier this month.
"WNV is spread from wild birds to humans, horses, and in some cases pets, through infected mosquitoes and causes encephalitis, or inflammation of the brain," said State Veterinarian Dr. Steven Halstead.
"Signs of WNV may include stumbling, limb weakness, facial paralysis, difficulty urinating and defecating, fever, blindness, seizures, and struggling to get up," Dr. Halstead said in a statement. "There is no specific treatment for WNV encephalitis, but supportive care can help horses survive until their natural defenses eliminate the virus."
Michigan Department of Agriculture and Rural Development partners with the Michigan State University Diagnostic Center for Population and Animal Health for diagnostic testing whenever clinical signs indicate the animal could be suffering from a reportable disease, Dr. Halstead said.
"Our commitment to diagnostic testing for new and emerging zoonotic diseases such as West Nile Virus strengthens partnerships with state agencies including MDARD, Department of Community Health, and Department of Natural Resources, as well as national agencies like the Centers for Disease Control and Prevention," said Dr. Carole Bolin, MSU, DCPAH Director. "We conduct approximately 100 tests for WNV annually."
"Licensed West Nile Virus vaccines for horses are available and owners are encouraged to vaccinate yearly, in consultation with private veterinary practitioners," said Dr. Halstead. "Horse owners should take measures to reduce the risk of mosquito exposure to themselves and their horses."
The mosquitoes most likely to transmit West Nile Virus to humans lay eggs in small pools of standing water. Adult mosquitoes can hatch in 10 days in the warmest months of the summer. Mosquitoes become infected and transmit West Nile Virus after feeding on birds carrying the virus. Within 10 to 14 days, the mosquito can transmit the virus to humans and horses.
Since West Nile Virus is spread to horses through the bite of an infected mosquito, protection measures that reduce the exposure to mosquito bites should be adopted. Horse owners should follow these tips to prevent mosquito-borne illness:
- Vaccinate. Inexpensive vaccines for WNV are readily available. It is not too late to vaccinate horses this season. Talk to your veterinarian for details.
- Use approved insect repellants to protect horses.
- If possible, put horses in stables, stalls, or barns, preferably under fans, during the prime mosquito exposure hours of dusk and dawn.
- Eliminate standing water, and drain troughs and buckets at least once a week.
West Nile Virus can also be spread to humans.
Most people bitten by a West Nile Virus infected mosquito show no symptoms of illness. However, some become sick three to 15 days after exposure.
Persons aged 55 and older are more susceptible to severe West Nile Virus disease symptoms.
Physicians are urged to test patients for West Nile Virus if they present with fever and signs of meningitis or encephalitis, or sudden painless paralysis in the absence of stroke in the summer months.
To reduce the chances of a mosquito bite, residents are encouraged to:
- Maintain window and door screening to help keep mosquitoes out of buildings.
- 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 two 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.