West Nile virus has been confirmed in three additional horses in Yakima County. None of the animals had been vaccinated against the disease.
Thursday's announcement follows on the heels of the state Department of Health report on Wednesday that a Pierce County man has been confirmed as the state's first human infection with West Nile virus. This year's first case of West Nile virus in a Washington horse, also in Yakima County, was reported on Aug. 18.
West Nile virus is spread by the bite of an infected mosquito and can sicken people, horses, many types of birds and other animals. Humans cannot contract West Nile through contact with an infected horse and infected horses do not spread the disease to other animals. Mosquitoes get infected when they feed on an infected bird. Reducing mosquito populations can minimize the threat of the virus.
"The best way to protect a horse from West Nile infection is vaccination," said State Veterinarian Leonard Eldridge. "We have seen an increase in the number of vaccinations, but too many owners still have not sought this preventative treatment. It's a simple procedure and a small price to pay to prevent the death of an animal."
The vaccine requires two doses three to six weeks apart, with immunity achieved five weeks after the second vaccine. An annual booster shot should be considered prior to the start of the mosquito season.
Many horses and other animals contracting the virus do not become ill and show no symptoms at all. Those that do become ill show signs such as loss of coordination, loss of appetite, confusion, fever, stiffness and muscle weakness, particularly in the hindquarters. About one-third of horses that become ill die.
Veterinarians and horse owners should report potential cases of West Nile virus in horses to the State Veterinarian's Office at (360) 902-1878.