An arbovirus is any virus that is transmitted by blood‑feeding arthropods such as mosquitoes, ticks or sandflies. The term is descriptive rather than taxonomic and encompasses viruses from several families that can replicate in both a vertebrate host and an invertebrate vector.
Explanation
Arboviruses establish a biological cycle between haematophagous arthropods and vertebrates. After ingestion of viremic blood, the virus infects the arthropod’s midgut, disseminates to the salivary glands and is transmitted to a new host during subsequent feeding. To be maintained in nature, the virus must replicate efficiently in two vastly different environments: warm‑blooded vertebrate tissues and the cooler bodies of arthropods. Arboviruses belong to diverse genera including Flavivirus (dengue, yellow fever, West Nile, Zika), Alphavirus (chikungunya, Eastern equine encephalitis), Orthobunyavirus (La Crosse), Phlebovirus (Rift Valley fever), Nairovirus (Crimean‑Congo hemorrhagic fever) and Orbivirus (Bluetongue). Human disease ranges from self‑limited febrile illness to hemorrhagic fever and severe encephalitis. Transmission dynamics depend on vector competence, environmental conditions, reservoir hosts and human behaviour. Climate change and global travel have expanded the range of many mosquito species, leading to the emergence of arboviruses in new regions.
Notable arboviral diseases
Dengue fever is caused by four serotypes of dengue virus transmitted by Aedes aegypti and Aedes albopictus mosquitoes, resulting in millions of infections annually with a risk of severe dengue hemorrhagic fever. Zika virus, also spread by Aedes mosquitoes, can cause congenital abnormalities when pregnant women are infected. West Nile virus, maintained in bird‑mosquito cycles, emerged in North America in 1999 and now causes seasonal outbreaks of febrile illness and neuroinvasive disease. Chikungunya virus produces debilitating arthralgia and has spread beyond Africa and Asia to the Americas. Tick‑borne encephalitis virus is transmitted by Ixodes ticks in Europe and Asia and causes meningoencephalitis. Rift Valley fever virus, carried by various mosquito species, affects livestock and humans in Africa.
Arboviruses pose ongoing public health challenges because control depends on vector management and, for some viruses, vaccination. Surveillance and rapid response are essential to mitigate outbreaks.
Related Terms: Flavivirus, Vector, Mosquito, Tick, Zoonosis