The Asian tiger mosquito, which has spread to at least 26 U.S. states, poses a risk for spreading West Nile virus (WNV) and other diseases, according to Sandra Fryhofer, MD, writing for Georgia Public Broadcasting. This mosquito species,  Aedes albopictus, is an aggressive feeder that bites all day.

According to the U.S. Centers for Disease Control and Prevention, A. albopictus is best known for transmitting dengue and chikungunya viruses but it has also been found infected with WNV,  Eastern equine encephalitis and Japanese encephalitis, and can transmit dog heartworm parasites.

Birds serve as a reservoir for the WNV, and mosquitoes can transmit the virus to humans and other mammals, particularly horses.

According to Fryhofer, there were 286 human deaths from WNV in 2012, the highest since 1999, when the virus was first detected in the United States, and the largest number of cases, at 5,674, since 2003.