Arthropod-Borne (Arbo) Viral Diseases
- arthropod-borne viruses, or arboviruses, are a group of infectious agents that are transmitted by blood-sucking arthropods from one vertebrate host to another. They can multiply in the tissues of the arthropod without evidence of disease or damage. The vector acquires a lifelong infection through the ingestion of blood from a viremic vertebrate
- all arboviruses have an RNA genome, and most have a lipid-containing envelope and consequently are inactivated by ether or sodium deoxycholate
- families in the current classification system that have some arbovirus members include
- Bunyaviridae (comprising the bunyaviruses, phleboviruses, nairoviruses, and hantaviruses)
- Flaviviridae (comprising only the flaviviruses)
- Reoviridae (comprising the coltiviruses and orbiviruses)
- Togaviridae (comprising the alphaviruses)
Most viruses associated with hemorrhagic fevers are classified in the families Arenaviridae and Filoviridae.
- note though that some flaviviruses ( yellow fever, dengue viruses) and some Bunyaviridae ( Rift Valley fever virus, Crimean-Congo hemorrhagic fever virus, and the hantaviruses) may be associated with hemorrhagic symptoms.
Arboviruses number > 250 and are distributed worldwide; at least 80 cause human disease
- birds are often reservoirs for arboviruses, which are transmitted by mosquitoes to horses, other domestic animals, and humans
- other reservoirs for arboviruses include arthropods and vertebrates (often rodents, monkeys, and humans)
- some arboviruses viruses may spread to humans directly from nonhuman reservoirs, but human-to-human transmission may also occur
- most arboviral diseases are not transmissible by humans
- exceptions include dengue fever, yellow fever, Zika virus infection, and chikungunya disease, which can be transmitted from person to person via mosquitoes. Also, Zika virus can be transmitted during sexual activity from infected symptomatic or asymptomatic men to their sex partners (male or female) or from infected women to their sex partner