the emergence and history of arboviruses

posted on january 28, 2019   by matt bassett

the name ‘arbovirus’ is an acronym for arthropod-borne virus, referring to viruses that are transmitted by arthropods, for example mosquitoes and ticks. well known arboviruses include dengue, west nile, yellow fever and zika virus. although malaria is mosquito-borne, it is a protist, not a virus, and so is not an arbovirus.

smuay/istock

the history of arboviruses

one of the most common vectors for arboviruses is aedes aegypti, or the yellow fever mosquito. as well as yellow fever, this one species can spread dengue, chikungunya, zika and mayaro. due to slave trade in africa and rising globalisation, the range of a. aegypti expanded dramatically throughout the 15th to 19th centuries. this resulted in many dengue fever epidemics that spread through asia, africa and north america in the 18th and 19th centuries.

the first proposal of arthropods being vectors for disease wasn’t put forward until 1881 when carlos finlay, a cuban doctor and scientist, suggested that yellow fever was not transmitted by human contact as originally thought, but by mosquitoes. it wasn’t until 1901, 20 years later, that major walter reed confirmed the idea.

the next major discovery came five years later in 1906, when dengue fever was found to be transmitted by a. aegypti, making it and yellow fever the first two diseases known to be caused by viruses. following this came the discoveries of tick-borne encephalitis in 1936 and west nile virus in 1937.

due to an increase in global transport links, adaptation of arthropod vectors to cities, increased range due to climate change and failure to contain outbreaks of mosquitos, arboviruses have seen a rapid, wide-spread emergence in recent years. according to the world health organization (who), before 1970 just nine countries had experienced serious dengue epidemics, but the disease is now endemic in over 100 countries.

whilst emergence of arboviruses is increasing worldwide, one arbovirus has been of particular concern in recent years. in 1947 zika virus was first identified in monkeys; five years later the disease was discovered in humans. for the following decades zika’s range spread, but there were no outbreaks and only 14 human cases of zika were documented. due to the lack of cases, the virus was not of overall concern until 2007, when there was a large outbreak on the pacific island of yap. in the following years, intense investigations were conducted into the major outbreaks in four other pacific islands. after a major 2015 outbreak in brazil, incidences of microcephaly (a birth defect where the baby’s head is much smaller than normal) rose sharply. shortly after the outbreak it was announced that zika is associated with the increase in microcephaly and other neurological disorders.

future study

the emergence of zika and increasing incidence of other arboviruses shows that new research into arboviruses is still needed. the third international meeting on arboviruses and their vectors will take place on september 5–6 at the university of glasgow. as part of the 2017 meeting, the ‘arboviruses and their vectors’ collection was launched. curated by the journal of general virology, the collection presents the latest in arbovirus research.

in conjunction with the meeting, the journal of general virology is opening the collection for submissions, welcoming original research and review articles. authors should submit their manuscript to the online submission system, indicating in their cover letter that the manuscript is intended for the ‘arboviruses and their vectors’ collection. for review articles, authors should first contact colin crump, reviews editor, via [email protected].

further reading from the collection

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