Abstract
The arboviruses constitute a set defined by the epidemiologic fact that they are transmitted between vertebrate hosts through the agency of biting, blood-sucking arthropods. The word arbovirus is an abbreviation for arthropod-borne virus of vertebrates; it defines a concept not related to the chemical, physical, or morphological properties of the virion. Arboviruses are viruses that are maintained in nature principally, or to an important extent, through biological transmission between susceptible vertebrate hosts by hematophagous arthropods. In the strict sense, the definition of arbovirus requires that the cycle of biological propagation from arthropod to vertebrate and back to arthropod be observed under controlled conditions as it occurs in nature. Properties of a virus that are not directly related to the transmission cycle, though helpful at times for orientation, should not be entertained as defining criteria. Easy isolation and propagation by intracerebral inoculation into newborn or adult mice or the inactivation of the virus by lipid solvents are properties shared with other viruses not remotely suspected of being arthropod-borne such as herpes and rabies.