The association between Zika virus infection and microcephaly in Brazil 2015–2017: An observational analysis of over 4 million birthsby Brady et al.
This study strengthens the evidence that congenital ZIKV infection, particularly in the first 2 trimesters of pregnancy, is associated with microcephaly and less frequently with other birth defects. The finding of no alternative causes for geographic differences in microcephaly rate lead the authors to hypothesize that the Northeast region of Brazil was disproportionately affected by this Zika outbreak, with 94% of an estimated 8.5 million total cases occurring in this region, suggesting a need for seroprevalence surveys to determine the underlying reason.
In 2015–2016 in the Recife Metropolitan Region, the authors of this study detected the tail end of a Zika epidemic, which was displaced by a chikungunya epidemic. Few dengue cases were identified despite a high number of official dengue notifications in the area during this period. This study shows here important epidemiological features of these cases.
Results from this study suggest that ZIKV has mechanisms to evade mosquito innate immunity and it is therefore important to understand virus-vector interactions and the implications they have on transmission.