Zika Virus, Microcephaly and Guillain-Barre Syndrome
- WHO and partners have established a definition of what constitutes an outbreak, endemic transmission, and the interruption of vector-borne transmission in order to better characterize the level of transmission of Zika virus infection (Table 1, Fig. 2). In addition, this will facilitate public health recommendations for residents and travellers. Based on these definitions, countries and territories reporting mosquito-borne Zika virus transmission were reclassified.
- As of 6 July 2016, 65 countries and territories (Fig. 1, Table 1) have reported evidence of vector-borne Zika virus transmission since 2007 (62 of these countries and territories have reported evidence of vector-borne Zika virus transmission since 2015):
- 48 countries and territories with a first reported outbreak from 2015 onwards (Table 1).
- Four countries are classified as having possible endemic transmission or have reported evidence of local vector-borne Zika infections in 2016.
- 13 countries and territories have reported evidence of local vector-borne Zika infections in or before 2015, but without documentation of cases in 2016, or with outbreak terminated.
- Guinea-Bissau is the latest country to report mosquito-borne Zika virus transmission.
- Eleven countries have reported evidence of person-to-person transmission of Zika virus, probably via a sexual route (Table 2). Spain is the latest country to report Zika infection through person-to-person transmission.
- As of 6 July 2016, microcephaly and other central nervous system (CNS) malformations potentially associated with Zika virus infection or suggestive of congenital infection have been reported by 13 countries or territories. Three of those countries reported microcephaly cases born from mothers with a recent travel history to Zika-affected countries in Latin America (Table 3).
- As of 6 July, the United States Centers for Disease Control and Prevention (US-CDC) reported seven live-born infants with birth defects and five pregnancy losses with birth defects with laboratory evidence of possible Zika virus infection.
- In the context of Zika virus circulation, 15 countries and territories worldwide have reported an increased incidence of Guillain-Barré syndrome (GBS) and/or laboratory confirmation of a Zika virus infection among GBS cases (Table 4).
- Based on research to date, there is scientific consensus that Zika virus is a cause of microcephaly and GBS.
- A case of GBS has recently been confirmed positive for Zika virus in Jamaica.
- Zika virus infections were diagnosed in eight cases with severe neurologic conditions in Guadeloupe.
- A WHO mission to Guinea-Bissau will be conducted to assist in understanding the lineage of the Zika virus detected in the country using viral sequencing. The mission will also focus on the identification of priority activities to strengthen national response capacity.
- The global Strategic Response Framework launched by WHO in February 2016 encompasses surveillance, response activities and research. An interim report3 describing some of the key activities being undertaken jointly by WHO and international, regional and national partners in response to this public health emergency was published on 27 May 2016. A revised strategy for the period of July 2016 to December 2017 was published on 17 June.
- WHO has developed new advice and information on diverse topics in the context of Zika virus.5 WHO’s latest information materials, news and resources to support corporate and programmatic risk communication and community engagement are available online
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Common Management Taxonomy: