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Zika virus and complications: Questions and answers

Online Q&A
Updated 10 March 2017

Summary of the situation

The rise in the spread of Zika virus in Brazil has been accompanied by an unprecedented rise in the number of children being born with unusually small heads—identified as microcephaly. In addition, several countries, including Brazil, reported a steep increase in Guillain-Barré syndrome—a neurological disorder that could lead to paralysis and death. 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 Guillain-Barré syndrome. Zika virus continues to spread geographically to areas where mosquitoes are present that can transmit the virus.

Zika virus

How do people catch Zika virus?

What are the symptoms of Zika virus disease?

How is Zika virus disease diagnosed?

How is Zika virus disease treated?

Zika virus country classification scheme

Why do we need a Zika virus country classification scheme?

Why does the scheme only take into consideration the presence in a country of the Aedes aegypti mosquito and not of other mosquitoes?

What are the categories in the Zika virus country classification scheme?

What are the public health implications of this classification?

How was the Zika virus country classification scheme developed?

Zika and neurological complications

What is microcephaly?

What is congenital Zika virus syndrome?

What is Guillain-Barré syndrome?

What is the relationship between Zika and microcephaly and Guillain-Barré syndrome?

What events led WHO to investigate a causal link between Zika virus and complications including microcephaly and Guillian-Barré syndrome?

Are there other explanations for microcephaly and Guillain-Barré syndrome?

Mosquitoes transmitting Zika virus

Where does Zika virus occur?

Can the Aedes mosquito travel from country to country and region to region?

Mosquito surveillance and control

What role does mosquito surveillance play in addressing Zika virus?

What role does mosquito control play in addressing Zika virus?

Protection from Zika transmitted by mosquitoes

What can people do to protect themselves from mosquito bites?

How can pregnant women protect themselves from mosquito bites?

Prevention of sexual transmission of Zika virus

What can people do to be protected from sexual transmission of Zika virus?

What should women do if they have been exposed to unprotected sex but do not wish to become pregnant because of possible infection with Zika?

Vaccine research and development

Who might be targeted for vaccination against Zika?

What steps are required to ensure that a vaccine is safe and effective?

What is the current status of Zika vaccine development?

How is WHO expediting Zika vaccine R&D?

When might a Zika vaccine be available?

What are the characteristics of an ideal Zika vaccine?

What are the challenges in Zika vaccine R&D?

What happens once a vaccine is available?


Can women transmit Zika virus to their fetuses during pregnancy or childbirth?

What should women do if they wish to postpone pregnancy because they are worried about microcephaly?

How can women manage their pregnancy in the context of Zika virus and complications?

Can mothers with Zika infection breastfeed their baby?


What should people travelling to Zika-affected areas do?

Zika virus response

What is WHO's response to Zika?

What does WHO recommend countries to do?

References: i

Besnard M, Lastere S, Teissier A, Cao-Lormeau V, Musso D. Evidence of perinatal transmission of Zika virus, French Polynesia, December 2013 and February 2014. Eurosurveillance 2014 Apr 3;19(13):20751. Available from:

Dick GWA. Zika virus. II. Pathogenicity and physical properties. Trans R Soc Trop Med Hyg 1952 Sep;46(5):521–34. Available from:


Zika virus - Questions and answers (Q&A)

Related links

Information in Portuguese

This page links all WHO technical and general information on Zika virus and potential complications in Portuguese.