General aspects on arboviruses

Abstract

Arboviruses do not represent a based related phylogenetic group but they are all transmitted by arthropods. A total of 50 arboviruses pathogenic for animals (including humans) have been reported, belonging to the families Asfarviridae, Bunyaviridae, Flaviviridae, Orthomyx-oviridae, Rhabdoviridae, Reoviridae and Togaviridae. A wide variety of hematophagous arthropods transmits the arboviruses: biting midges, cimicid bugs, mosquitoes, sand flies and ticks. The vector acquires the infection by blood feeding from a viremic host and transmits the virus to a new host by the oral route (inoculating infected saliva). However, vertical transmission routes already exist (transovarian, venereal). Arbovirus can be amplified by a diverse range of vertebrate hosts including birds, rodents, equines, humans and monkeys. Through biological evolution and cultural development, human beings were able to modify the environments according to their needs. Thus, deforestation has produced new areas for agriculture, livestock, farming activities and urbanization. These anthropogenic activities have produced great changes to host and vector communities and population abundance, sometimes driving emergence and reemergence of arboviruses. In this chapter we give a general view for most important aspects of arboviruses, they classification, transmission and maintenance mechanisms, ecology and emergence process.