Guidelines for surveillance of Zika virus disease and its complications

Zika virus (ZIKV) is an arbovirus of the genus Flavivirus (family Flaviviridae), phylogenetically very close to other viruses, such as the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. It is a mosquito-borne RNA virus, transmitted mainly by the genus Aedes, and was first isolated in 1947, from a Rhesus macaque, during a study on the transmission of jungle yellow fever in the Zika Forest of Uganda.

In 1968, it was first isolated in humans in Uganda and in the United Republic of Tanzania. Subsequently, outbreaks have been recorded in Africa, Asia, the Western Pacific region and, more recently, in the Americas. Sexual and vertical (mother-to-child) transmission of ZIKV have been documented in a limited number of cases, as has transmission through blood transfusion. Transmission through breast milk has not been documented, however it may be possible as viral RNA has been found in the breast milk of women who were infected during the peripartum period; more recently, a report of infective ZIKV particles in breast milk has been published.

The symptoms of the disease usually appear after an incubation period of 3 to 12 days, and are similar to those of other arboviral infections; they include rash, fever, conjunctivitis, myalgia, arthralgia, malaise, and headache, and tend to last 4 to 7 days. During an outbreak that occurred in French Polynesia in 2013 and 2014, an increase in cases of Guillain-Barré syndrome (GBS) and other neurological manifestations was observed in association with ZIKV infection and recently, in the Americas, it has also been associated with other neurological manifestations. In October 2015, the health authorities of Brazil confirmed an increase in the prevalence of microcephaly at birth in the Northeast region of the country, which coincided in time with an outbreak of the ZIKV. Subsequently, other birth defects, placental insufficiency, intrauterine growth restriction, and fetal death were described in association with ZIKV infection during pregnancy.

The latter event led the World Health Organization (WHO) to declare on 1 February 2016 a public health emergency of international concern (PHEIC) and to recommend enhancement of surveillance and research on the relationship between new clusters of microcephaly and other neurological disorders, including Guillain-Barre syndrome and ZIKV infection.