How is the West Nile Virus spread?
WNV is spread to humans by the bite of an infected mosquito. The transmission cycle below illustrates that a bird becomes infected after being bitten by a mosquito carrying the virus. Several suspected mosquito species are involved in the transmission of WNV. Horses and other animals bitten by infected mosquitoes can also become infected. A human or horse that has the disease cannot spread the virus. Whenever mosquitoes are active there is a risk of getting WNV, therefore the highest probability of acquiring the virus exists during the months from late July through September. Although a vaccine is available for horses, there is currently no vaccine for humans.
