Togaviridae

Abstract

Alphavirus constitutes one of the two genera included in the family Togaviridae. This genus contains 31 viral species (with different variants and strains), grouped into seven antigenic complexes. Depending on the geographical location where they were isolated, this genus is divided into alphavirus in the New World (including Eastern equine encephalitis virus, Venezuelan equine encephalitis, and Western equine encephalitis, which cause encephalitis in humans and other mammals) and the Old World (chikungunya virus, oʼnyong-nyong virus, Ross River virus, Semliki Forest virus, and Sindbis virus causing syndrome characterized by fever, rash, and arthralgias, which rarely cause mortality). However, Sindbis virus (the prototype alphavirus) causes encephalomyelitis in mice, and Ross River virus and chikungunya virus (CHIKV) are also neuroinvasive and cause neurological disease in humans. Alphaviruses are responsible for several medically important emerging diseases and are also significant veterinary pathogens. Due to the aerosol infectivity of some alphaviruses and their ability to cause severe, sometimes fatal neurological diseases, they are also of biodefense importance. Likewise, they are of interest for their potential use in gene therapy. This chapter will describe general aspects of alphavirus, with emphasis on their pathology, ecology, epidemiology, clinical, diagnosis, treatment, prevention, and control measures.