We asked friends on Facebook and Twitter what questions they had about West Nile virus, and we got the answers from health experts.
David Rancken wrote, "If people cases of West Nile are supposed to be rare, how many people could be walking around here with West Nile and don't even know it?"
According to the Centers for Disease Control and Prevention, about 80 percent of people infected with West Nile virus show no symptoms and probably have no idea they have contracted it.
Up to 20 percent of those infected with West Nile virus may experience headaches, body aches, nausea and vomiting. Only about one in 150 people infected develop severe illness.
West Nile virus is spread by infected mosquitoes, but in very small numbers it has been spread through blood transfusions, organ transplants, breast feeding and pregnancy.
West Nile virus cannot be spread through casual contact, like touching or kissing.
"If you get West Nile, is there treatment for it?" Rachel Sherman asked.
There is no specific treatment for West Nile virus. Health officials said mild cases usually improve on their own. Severe symptoms require hospitalization.
"Does the virus affect dogs?" Gwen Dupre Sorensen asked.
The CDC reports very few dogs and cats have been infected with West Nile virus, but it's highly unlikely that pet owners would notice any unusual symptoms or behavior.
Like for humans, there is no specific treatment for pets.
There is no data showing the virus can be spread from dogs or cats to people.
The CDC recommends not using repellant with DEET on animals, mostly because they can ingest it by licking themselves. It's best to check with a veterinarian for a mosquito repellant appropriate for your pet.