ZIKA virus circulates in new regions

Journal name:
Nature Reviews Microbiology
Year published:
Published online

Named after the forest in Uganda from which it was first isolated in 1947, Zika virus (ZIKV) is a flavivirus transmitted by Aedes spp. mosquitos. Although the widespread distribution of the vector may make many regions vulnerable to ZIKV, the virus was confined to Africa and Asia until 2007, when it arrived in Oceania. However, in the past year, ZIKV has been circulating in the Americas, where concerns have now been raised over possible links with microcephaly (a congenital growth impairment of the head).

During February–June 2014, an outbreak occurred on Easter Island, Chile, where ZIKV is thought to have been introduced by French Polynesians attending a cultural festival (Emerg. Infect. Dis. 21, 1887; 2015). In May 2015, Brazil confirmed the first cases of ZIKV to originate in the continental Americas, followed, in October–December, by Colombia, El Salvador, French Guiana, Guatemala, Honduras, Mexico, Panama, Paraguay, Suriname and Venezuela (PAHO, 23 Dec 2015). Outside of the Americas, the Atlantic island nation of Cape Verde announced its first ZIKV epidemic in October, with 4,744 suspected cases by 6 December (WHO, 21 Dec 2015).

ZIKV is only rarely associated with severe disease requiring hospitalization. However, as of 28 November 2015, three deaths had been attributed to ZIKV in Brazil, including the death of a newborn with microcephaly. The ZIKV genome was detected in blood and tissue samples from this baby, and the Brazilian health ministry believes that ZIKV is linked to a 20-fold increase in cases of microcephaly in regions where the virus is circulating, and has warned of a risk to pregnant women (BBC News, 29 Nov 2015; PAHO, 1 Dec 2015). However, the CDC cautions that flaviviruses are not known to cause microcephaly, and that any possible association remains under investigation (CDC, 15 Dec 2015).

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