ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD
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The alphaviruses constitute an important genus of the Togaviridae family. They are transmitted by mosquitoes, and their major ecological maintenance strategy is passage from mosquito to vertebrate to mosquito. Thus, an understanding of their epidemiology requires an appreciation of the factors that regulate populations of arthropods, vectors, and their interactions, as well as knowledge of the viral genome and its phenotypic expression. In many cases, humans are not the major vertebrate amplifier, but rather an accidental target of virus infection with no significance in the further propagation of virus. When humans are infected, the consequences can range from asymptomatic seroconversion to devastating illness. In this chapter we attempt to summarize basic concepts of the classification of these viruses, their ecological strategies and epidemic potential, clinical disease manifestations, and prospects for their control. Their replication strategy is discussed in detail in Chapter 25, but this chapter presents molecular data that bear on these biological issues. We concentrate on the viruses of greatest biomedical significance but even in the case of very important viruses, many uncertainties exist in our knowledge base. Keywords Reprints Morphology.