Brazil’s microcephaly epidemic continues to pose a mystery — if Zika is the culprit, why are there no similar epidemics in other countries also hit hard by the virus? In Brazil, the microcephaly rate soared with more than 1,500 confirmed cases. But in Colombia, a recent study of nearly 12,000 pregnant women infected with Zika found zero microcephaly cases. If Zika is to blame for microcephaly, where are the missing cases? Perhaps there is another reason for the epidemic in Brazil. According to a new report by the New England Complex Systems Institute (NECSI), the number of missing cases in Colombia and elsewhere raises serious questions about the assumed connection between Zika and microcephaly.