The Centers for Disease Control and Prevention (CDC) have confirmed reports of West Nile virus in 10 states. The bite of an infected mosquito most commonly spreads the virus.
"West Nile virus is the leading cause of mosquito-borne illness in the U.S.," says Dr. Bobbi Pritt, director of the Clinical Parasitology Laboratory at Mayo Clinic.
It's a flavivirus —a specific type of RNA virus that can infect humans, birds and horses.
