Eastern Equine Encephalomyelitis Virus: Epidemiology and Evolution of Mosquito Transmission

Abstract

This chapter focuses on the role of mosquitoes in the enzootic transmission of eastern equine encephalomyelitis (EEE) virus and discusses the historic and epidemiologic knowledge, structure and replication, and transmission cycles of the virus. Studies on mosquito–virus interactions and speculation on the significance of these findings have been summarized in the chapter. Early studies of EEE virus described the disease caused by this virus, identified the virus as an etiological agent, and determined arthropod and vertebrate hosts for enzootic and epidemic transmission. Subsequent studies provided important details on mosquito bionomics, vector–virus interactions, and basic virology. Because EEE virus is easy to work with in the laboratory, the virus has also been used as a model for testing concepts in entomological aspects of arbovirology. Multiple blood-feeding by mosquitoes during a single gonotrophic cycle increases the probability of virus persistence during interepidemic periods and the explosive spread of diseases during epidemics. EEE virus transmission cycles can be used to test the importance of this prediction. Moreover, the techniques that are being developed—histological examination of engorged mosquitoes and alkali metal blood markers in sentinel hosts—have broad application to hematophagous arthropods that transmit a variety of diseases.