Epidemiology and surveillance
Zika virus disease - Interim case definition
These interim case definitions have been developed for the purpose of providing global standardization for classification and reporting of Zika virus cases. WHO guidance for the surveillance of Zika virus disease is currently being developed.
WHO will periodically review these interim case definitions and update them as new information becomes available.
Surveillance for Zika virus infection, microcephaly and Guillain-Barré syndrome
This document provides interim WHO recommendations for the surveillance of Zika virus and potentially related complications. It has been developed in consideration of the declaration on 1 February 2016 by the WHO Director-General of a Public Health Emergency of International Concern with regard to clusters of microcephaly and neurological disorders potentially associated with Zika virus.
This document provides interim recommendations for the surveillance of Zika virus infection, microcephaly and Guillain-Barré syndrome, in four different contexts and describes reporting requirements to WHO. Transmission refers to vector-borne transmission, unless specified differently. Autochthonous infection is considered to be an infection acquired in-country, i.e. among patients with no history of travel during the incubation period or who have travelled exclusively to non-affected areas during the incubation period. This document does not provide guidance on laboratory investigation or vector surveillance.
Zika virus country classification scheme
Overview
The geographical distribution of Zika virus (ZIKV) has expanded globally, particularly since 2015 in the Americas. Since 2013, 31 countries and territories have reported cases of microcephaly and other central nervous system malformations associated with ZIKV infection, as of 17 February 2017. There are significant knowledge gaps around ZIKV and a lack of historical data on its vectors, transmission dynamics, and geographical distribution. Despite these challenges, there is a need to better describe the epidemiology of ZIKV transmission in a given place, at a given time in order to allow an assessment of the possibility of ZIKV infection for various populations, and to adapt public health recommendations accordingly for residents and travellers.
The proposed definitions in this interim guidance refine and replace those presented in the WHO interim guidance on surveillance for ZIKV infection, microcephaly and Guillain-Barré syndrome (7 April 2016).
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