Life-Threatening Cache Valley Virus Infection

Abstract

The Bunyamwera serogroup (family Bunyaviridae, genus bunyavirus) contains more than 20 serologically cross-reactive viruses, 7 of which have been isolated in North America.¹ Cache Valley virus, first isolated in Utah in 1956,² has been recovered mainly from mosquitoes (genera culiseta, aedes, and anopheles) and occasionally from vertebrates and has the widest apparent distribution among this serogroup of viruses. Antibodies against Cache Valley virus and other viruses of the Bunyamwera serogroup are prevalent in livestock, large wild mammals, and humans from Alaska to Argentina.³ An association between Cache Valley virus infections and congenital malformations (various musculoskeletal and central nervous system defects) was described in sheep⁴ and later experimentally reproduced in sheep⁵ and cattle. Recent serologic studies suggest that the viruses of the Bunyamwera serogroup may also be etiologic agents of congenital defects of the central nervous system in humans.⁶ Although antibodies against Cache Valley virus have been reported in humans, no acute infections or isolations of the virus have been reported, although a closely related virus was isolated from a febrile patient in Panama.⁷ We describe the isolation of Cache Valley virus from a patient with severe encephalitis and multiorgan failure.