Between 1 January 2007 and 25 February 2016, a total of 52 countries and territories have reported autochthonous (local) transmission of Zika virus, including those where the outbreak is now over and countries and territories that provided indirect evidence of local transmission. Among the 52 countries and territories, Marshall Islands, Saint Vincent and the Grenadines, and Trinidad and Tobago are the latest to report autochthonous transmission of Zika virus.
The geographical distribution of Zika virus has steadily widened since the virus was first detected in the Americas in 2015. Autochthonous Zika virus transmission has been reported in 31 countries and territories of this region. Zika virus is likely to be transmitted and detected in other countries within the geographical range of competent mosquito vectors, especially Aedes aegypti.
So far an increase in microcephaly cases and other neonatal malformations have only been reported in Brazil and French Polynesia, although two cases linked to a stay in Brazil were detected in two other countries.
During 2015 and 2016, eight countries and territories have reported an increased incidence of Guillain-Barré syndrome (GBS) and/or laboratory confirmation of a Zika virus infection among GBS cases.
Evidence that neurological disorders, including microcephaly and GBS, are linked to Zika virus infection remains circumstantial, but a growing body of clinical and epidemiological data points towards a causal role for Zika virus.
The global prevention and control strategy launched by WHO as a Strategic Response Framework encompasses surveillance, response activities and research, and this situation report is organized under those headings. Following consultation with partners and taking changes in caseload into account, the framework will be updated at the end of March 2016 to reflect epidemiological evidence coming to light and the evolving division of roles and responsibilities for tackling this emergency.