Introduction

The Director-General of the World Health Organization (WHO) convened an Emergency Committee under the International Health Regulations (2005) on 1 February 2016.

Following the advice of the Committee, the Director-General announced the recent cluster of microcephaly and other neurologic disorders reported in Brazil to be a Public Health Emergency of International Concern.

Background Information

Microcephaly: It is a rare (1 in several thousand) condition where a baby is either born with a small head or the head stops growing after birth.

The most reliable way to assess whether a baby has microcephaly is to measure head circumference 24 hours after birth, compare the value with WHO growth standards, and continue to measure the rate of head growth in early infancy.

There are no specific tests to determine if a baby will be born with microcephaly, but ultrasound scans in the third trimester of pregnancy can sometimes identify the problem.

Often, the cause for microcephaly is not known. The most common causes include:

• infections during pregnancy: toxoplasmosis (caused by a parasite found in undercooked meat), rubella, herpes, syphilis, cytomegalovirus and HIV;
• exposure to toxic chemicals: maternal exposure to heavy metals like arsenic and mercury, alcohol, radiation, and smoking;
• genetic abnormalities such as Down syndrome; and
• severe malnutrition during fetal life.

 There is no specific treatment for microcephaly.

Key Messages:

Although a  causal relationship between Zika infection during pregnancy and microcephaly is strongly suspected, it is not yet scientifically proven.

Between January 2014 and 5 February 2016, a total of 33 countries have reported autochthonous circulation of Zika virus. There is also indirect evidence of local transmission in 6 additional countries.

The geographical distribution of Zika virus has been steadily increasing since it was first detected in the Americas in 2015. Further spread to countries within the geographical range of competent disease vectors — Aedes mosquitoes — is considered likely.

Seven countries have reported an increase in the incidence of cases of microcephaly and/or Guillain-Barré syndrome concomitantly with a Zika virus outbreak.

Global Response Strategy:

Surveillance:

Enhance surveillance for Aedes mosquitoes, Zika virus disease, neurologic syndromes, and congenital malformations.

Response:

Engage communities to communicate the risks associated with Zika virus disease and promote healthy behaviors, reduce anxiety, address stigma, dispel rumors, and cultural misperceptions

Increase efforts to control the spread of the Aedes mosquito and provide increased access to personal protection measures

Provide guidance and care for pregnant women and those considering pregnancy, as well as families with children affected by microcephaly, congenital malformations and neurologic syndromes

Research:

Fast-track the investigation of the etiology of microcephaly, neurologic syndromes and possible association with consequences of Zika virus infection; research and development of new products (e.g. rapid diagnostics, vaccines, therapeutics)

Useful Links:

Link to the full Situation Report:

http://apps.who.int/iris/bitstream/10665/204348/1/zikasitrep_5Feb2016_eng.pdf?ua=1

Link to WHOs factsheet on Microcephaly:

http://who.int/emergencies/zika-virus/microcephaly/en/

Link to WHOs fact sheet on Guillain-Barre Syndrome (updated 5 February 2016):

http://who.int/mediacentre/factsheets/guillain-barre-syndrome/en/