Reviewer response for version 1
Thank you for the opportunity to review this article. 
I have the following questions/suggestions for the consideration of the authors:
- The following important reference is missing from the article, please include: Rasmussen et al. (2016) 1
- Authors should mention that Zika migrated not only to Brazil but to the Americas.
- What are the characteristics of the chosen hospital? 
Why only one hospital was chosen? 
Does the hospital has a good reliable birth defect registry?
- There is no description of the birth defects taken into account for the paper; which CZS-type birth defects were chosen form the hospital registry? 
Were the birth defects confirmed? 
Was any description available in medical records? 
Were X-rays available for review?
- I agree with the authors on the importance to have birth defects surveillance systems in place. 
I hope that this article will contribute to the awareness of public health authorities regarding this important issue.
- Birth defects surveillance is needed to identify Zika related defects. 
As the authors mention, the majority of infected pregnant women are asymptomatic.
- I think it will be important to differentiate in the article between Zika virus surveillance and birth defects surveillance, and the difficulties of implementing them in Africa.
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