Due to the small number of ZF patients examined, this study and the strength of the observations are limited.
We have analyzed cytokine levels over time in returning travelers to Europe, and it is unknown whether different human ethnic groups might show different cytokine responses as described for DF [18]. Recent ZF epidemics were only caused by the Asian genotype of ZIKV, which is the same genotype also seen in travel-related infections from outbreak areas. Thus, the cytokine data presented here are linked to an infection with the Asian genotype.
As a restriction of the study, functional T cell tests (i.e.,stimulation with ZIKV antigen followed by intracellular
cytokine staining) have not been performed. Future studies will address lymphocyte and cytokine responses in more detail, allowing proper conclusions of Th1- and Th2-biased
cell responses. Despite showing rather preliminary data, to
our knowledge, this is the first study investigating immune
parameters in acute ZF.