Arbovirus is a truncated term for arthropod-borne viruses, all of which require multiplication in their vectors for transmission. Arboviruses diseases may be simpler to understand when viewed solely from the position of the end product, which is disease in humans or other vertebrates. The diseases fall into a few recognizable sets: (1) encephalitides; (2) diseases with fever and rash, often fairly benign; (3) diseases with hemorrhagic manifestations, often fatal; and (4) mild fevers, quite undiagnosable except through laboratory study. A common feature of all of these is periodic outbreaks, with dozens, hundreds, or thousands of cases. A second common feature is lack of specific treatment. In addition, only for very few of the diseases do vaccines exist. Possibility of disease control is real, however, and is based on a knowledge of the epidemiology of arbovirus infections in general, the role that vectors play, and the particular features in regard to the transmission of the specific disease in question.

Etiology

Arboviruses, numbering at latest count 512 separate and identifiable agents, are placed in 11 families, with a few as yet unclassified agents. Table VIII. 10.1 presents a listing of family and subfamily groupings, limited to those viruses of major importance in human and veterinary diseases.

It is evident from the table that there is no simple delimiting definition of an arbovirus on a taxonomic basis, or even on a biochemical basis. There are 511 RNA viruses, and then there is African swine fever virus (ASF), a DNA virus. ASF belongs to the Iridoviridae and is the only Iridovirus (so far as is yet known) with an arthropod vector and a vertebrate host.