The mosquito that carries WNV primarily targets birds, horses and humans.
"There are a lot of factors that can make this a pretty bad season for WNV," said Environmental Health Specialist Tami Schuler. "We have the upcoming rain storms that can lead to stagnant pools of water and now you add the abundance of green pools into the mix, we expect to be very busy."
Schuler said that the horse vaccine is not a one-time only solution for owners.
"Once the horse is vaccinated, it should be given a booster once a year for protection. But check with veterinarian to make sure the course of treatment is appropriate for the animal."
According to the American Association of Equine Practitioners (AAEP), a horse may experience symptoms such as: fever, ataxia (stumbling), depression or apprehension, stupor, behavioral changes, weakness of limbs, partial paralysis, droopy lip, teeth grinding, muscle twitching, tremors, difficulty rising, convulsions, blindness, colic, and intermittent lameness or death.
The AAEP says the fatality rate for horses with WNV is 33 percent. For those that survive, 40 percent have residual effects following WNV infection. The effects can be physical or behavioral.
"Horse owners can also take some basic actions to help further prevent their animals from getting WNV," Schuler added. "You have the basics such as removing old tires that can collect water, getting rid of stagnant water ponds on your property and changing the horse's water daily. Owners can use a pyrethroid insect repellant when mosquitoes are most active and should remove animal waste as frequently as possible. Owners can also hang box fans in their horses' stalls to prevent the mosquitoes from landing and biting. Mosquitoes are weak fliers."
Pinal County Division of Environmental Health Vector Program has been keeping busy trapping and testing mosquitoes for any signs of WNV in Pinal County. "We are keeping vigilant," Schuler said. "We are hoping Pinal County residents keep up the good work in ridding their property of standing water. If that happens, we can keep the mosquito population down for everyone, including the horses."