Togaviruses Not Associated with Human Disease

Most alphaviruses are arthropod-borne human pathogens. The exceptions are alphaviruses that have not been associated with human rash and fever or encephalitis, or that occur only in fish or in insects on marine mammals. Relatively little is known about the transmission cycles of these viruses, including Middelburg, Fort Morgan, Getah, Ndumu, Cabassou, Whataroa, Bebaru, Una, and Trocara viruses, and they have not often been isolated from mosquitoes or other arthropods, although some infect humans and other animals. Marine alphaviruses include salmonid viruses that cause sleeping disease and pancreas disease in farmed fish in Western Europe and North America, and the louse-borne elephant seal virus. These alphaviruses are discussed in this article.