MicrobiologyTier 2Medical Sciences concept

Viral taxonomy - arbovirus classification (flavivirus vs alphavirus)

Core concept

Arboviruses = arthropod-borne, classified by viral family, not by vector
Flaviviruses (ssRNA+): dengue, Japanese encephalitis (JEV), Zika, yellow fever, West Nile, Murray Valley encephalitis
Alphaviruses (Togaviridae, ssRNA+): chikungunya, Ross River virus, Barmah Forest virus

Key detail

Family	Examples	Typical syndrome
Flavivirus	Dengue, JEV, Zika, yellow fever, MVE	Haemorrhagic fever (dengue), encephalitis (JEV/MVE), congenital syndrome (Zika)
Alphavirus	Chikungunya, Ross River, Barmah Forest	Polyarthralgia/arthritis - prolonged joint symptoms

JEV is a flavivirus - a repeatedly tested pairing (vaccine-preventable, endemic in SE Asia/PNG)
Vectors: Aedes mosquitoes (dengue/Zika/chikungunya) vs Culex mosquitoes (JEV/WNV/MVE)

Clinical relevance

Prolonged polyarthralgia after travel to the Pacific/SE Asia -> alphavirus (chikungunya, Ross River), not flavivirus
Dengue - warning signs (plasma leakage, bleeding, third-spacing) distinguish severe from classic dengue
JEV vaccination considered for prolonged rural travel/residence in endemic areas

Correlations

Returning traveller fever workup
Dengue haemorrhagic fever / warning signs
Congenital Zika syndrome

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