Zika situation report
4 March 2016
Zika virus, Microcephaly and Guillain-Barré syndrome
- Between 1 January 2007 and 3 March 2016, a total of 52 countries and territories have reported autochthonous (local) transmission or indication of transmission of Zika virus (41 since 1 January 2015). Five of these countries and territories reported a Zika virus outbreak that is now over. In addition, three countries and territories have reported locally acquired infection, probably through sexual transmission.
- Among the 52 countries and territories, Lao People’s Democratic Republic is the latest to report autochthonous transmission of Zika virus. France, Italy and the United States of America have reported locally acquired Zika virus infection in the absence of any known mosquito vectors.
- 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 has only been reported in Brazil and French Polynesia, although two cases linked to a stay in Brazil were detected in the United States of America and Slovenia.
- During 2015 and 2016, 8 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.
- A recently published case control study in French Polynesia provides further evidence of a causal relationship between Zika virus infection and GBS.
- 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.