Arbovirus Fever

A rare viral disease caused by arboviruses and are classically characterized by encephalitis and hemorrhage, however, most commonly only aspecific fever is observed.

Clinical description

Arboviruses are a heterogeneous group of viruses transmitted by a hematophagous arthropod vector. The most well known and most severe disease caused by an arbovirus is yellow fever. Arboviruses belong to the following families: togaviridae (equine encephalitis; see this term) Chikungunya virus, flaviviridae (dengue, yellow fever, St Louis encephalitis and West Nile encephalitis; see these terms) and bunyaviridae (California encephalitis and Bunyaviral hemorrhagic fever; see these terms). Ticks, sandflies or mosquitoes are their vectors. Arboviruses predominate in tropical countries. They all show tropism towards small vessels and the central nervous system. The incubation period is 7-10 days, after which onset is sudden, with high fever, cephalalgia, aches, and general malaise that lasts 2 or 3 days. The disease can then either heal spontaneously or progress to a clinical presentation that is specific to each virus. Classical dengue fever and related syndromes are characterized by a macular rash, polyadenopathy, and minor hemorrhage, after which the symptoms resolve spontaneously. Hemorrhagic dengue is complicated by significant hemorrhage and a mortality rate that ranges from 10-20% (South East Asia and the Caribbean). Encephalitis ranges from mild, uncomplicated meningitis to severe cases. Arboviruses that cause encephalitis have been classified into four groups: American equine encephalitis, Japanese encephalitis complex, encephalitis caused by ticks, and California encephalitis. Yellow fever is caused by the amarillic or yellow fever virus and progresses in two phases: a red congestive phase with diffuse erythema and conjunctival hyperemia, followed by the yellow phase with hepatocellular failure. Mortality remains high.

Management and treatment

There are no effective drugs for this virus, however, an antiamarillic vaccine gives protection against the virus for 10 years. This vaccine is essential for the prevention of this severe disease and its use is regulated by international law. Studies are currently under way to adjust a vaccine for West Nile virus because no antiviral has so far been proved effective in vitro.