Mosquitofrog West Nile Virus is a rapidly emerging arbovirus transmitted primarily by mosquitoes.2,4 The primary hosts for West Nile Virus are birds (eg, crow, Blue Jay). Mosquitoes that feed oninfected birds can transmit the diseaseto humans. Humans and other animals (eg, horses) serve as incidental hosts. 2 Approximately 1 in 5 individualsinfected with WNV demonstratesymptoms, and 1 in 150 shows CNSinvolvement.2 A fulminant course is fatal. Excluding West Nile Virus, thereare four main arbovirus agents ofencephalitis: LAC encephalitis, EEE,WEE, and SLE. Most cases occur from June through September. SLE is themost common mosquito-transmittedhuman pathogen in the US.5 Incidencevaries with occurrence and intensity ofepidemic transmission. Populations atincreased risk include:• LAC — children• WEE — rural residents of the West• SLE — elderly, low income areas 5 No human vaccines are currently available.