WHO – updated Zika situation report – 15 September 2016

Key updates

  • Countries and territories reporting mosquito-borne Zika virus infections for the first time in the past week:
    • None
  • Countries in the Western Pacific Region have been reporting new cases as seen in Singapore, Philippines and Malaysia.
  • Countries and territories reporting microcephaly and other central nervous system (CNS) malformations potentially associated with Zika virus infection for the first time in the past week:
    • None
  • Countries and territories reporting Guillain-BarrĂ© syndrome (GBS) cases associated with Zika virus infection for the first time in the past week:
    • None
  • The 2016 Summer Paralympic Games continue in Rio de Janeiro, Brazil. WHO continues to provide technical support to the Ministry of Health to ensure the 2016 Summer Paralympic Games are as safe as possible for all athletes, volunteers, visitors and residents. There is a low, but not zero, risk of Zika transmission in this setting. All persons should continue to follow guidance on avoiding Zika infection.

Summary

  • 72 countries and territories have reported evidence of mosquito-borne Zika virus transmission since 2007 (70 with reports from 2015):
    • 55 with a reported outbreak from 2015 onward.
    • 5 with having possible endemic transmission or evidence of local mosquito-borne Zika infections in 2016.
    • 12 with evidence of local mosquito-borne Zika infections in or before 2015, but without documentation of cases in 2016, or with the outbreak terminated.
  • Since February 2016, 12 countries have reported evidence of person-to-person transmission of Zika virus.
  • 20 countries or territories have reported microcephaly and other CNS malformations potentially associated with Zika virus infection or suggestive of congenital infection. 4 of the 20 countries reported microcephalic babies born from mothers in countries with no endemic Zika virus transmission but who reported recent travel history to Zika-affected countries.
  • 18 countries and territories have reported an increased incidence of GBS and/or laboratory confirmation of a Zika virus infection among GBS cases.
  • In Guinea-Bissau, the investigation of five reported cases of microcephaly is ongoing.
  • Based on a systematic review of the literature up to 30 May 2016, WHO has concluded that Zika virus infection during pregnancy is a cause of congenital brain abnormalities, including microcephaly, and that Zika virus is a trigger of GBS. The findings, which emerge from a causality framework that WHO developed in February 2016 to appraise the strengths and weaknesses of available evidence about the causal relationships, also identify gaps in research and provide direction for further work.