Tahyna virus ("TAHV") is a viral pathogen of humans classified in the California encephalitis virus (CEV) serogroup of the virus family Bunyaviridae endemic to Europe, Asia, Africa and possibly China. TAHV is maintained in an enzootic life cycle involving several species of mosquito vectors, with hares, rabbits, hedgehogs, and rodents serving as amplifying hosts. Human TAHV infections generally occur in summer and early fall, with symptoms of fever, headache, malaise, conjunctivitis, pharyngitis, and nausea. TAHV disease can progress to involve the central nervous system, but fatalities have not been reported. Human infections are common in endemic areas, with neutralizing antibodies present in 60 to 80% of the elderly population.