According to the AAEP, West Nile virus (WNV) is the leading cause of arbovirus encephalitis in horses and humans in the United States. Since 1999, over 25,000 cases of WNV encephalitis have been reported in U.S. horses. Horses represent 96.9% of all reported non-human mammalian cases of WNV disease.
Diagram of mosquito to bird to horse to human by West Nile virus
According to the AAEP, West Nile virus (WNV) is the leading cause of arbovirus encephalitis in horses and humans in the United States.
© 2018 by Department of Health New window.
The case fatality rate for horses exhibiting clinical signs of WNV infection is approximately 33%. Data have supported that 40% of horses that survive the acute illness caused by WNV still exhibit residual effects, such as gait and behavioral abnormalities, 6-months post-diagnosis.
West Nile Virus (WNV) is a mosquito-borne viral infection that affects horses and humans. It is transmitted through the bite of infected mosquitos. Mosquitos lay their eggs in standing water, which develops into thousands of mosquitos in 7-10 days.
Take the following steps to minimize the risk of disease in your horses:
Vaccinate
Several licensed products are available. Contact your veterinarian to ensure the vaccination status of your horse is current.
Limit Exposure
- Dusk to Dawn–If possible, stable horses during active mosquito feeding times.
- Screens and Doors–Close stable doors and use screens to keep mosquitos from entering your barn.
- Fans –Utilize fans to keep air circulating. This keeps mosquitos out of the area.
- Flysheets–Use flysheets and fly masks as protection for your horse.
- Mosquito Repellents–Use horse safe insect repellents with Permethrin.
Eliminate Mosquito Larvae
- Mosquito Fish–These fish eat mosquito larvae that have just hatched from eggs.
- Mosquito Dunks–Doughnut shaped blocks that dissolve slowly in water and contain a pesticide that kills mosquito larvae. It is harmless to animals and fish. These can be found at local garden/hardware stores.
Eliminate Standing Water
- Water Troughs–Change water twice a week.
- Wheelbarrows–Dump and leave in an upright position to prevent water collection.
- Drains –Keep outdoor drains free flowing to eliminate standing water.
- Irrigation–Manage irrigation systems to minimize puddles and standing water.
- Leaks–Fix leaky hoses and faucets that may create puddles.
- Rain Gutters –Keep rain gutters clear of leaves and debris that can cause water pooling.
- Trash –Dispose of items that can hold water, including cans, cups and bags. Make sure trashcans are tightly covered to prevent rainwater from collecting.
- Ponds –Stagnant water breeds mosquitos. Aerate ornamental pools, stock with mosqquito fish, and/or use mosquito dunks.
Press release by CDFA