Bezlotoxumab and Recurrent Clostridium difficile Infection

of some other unknown cofactor that is not es sential for GBS is required.A third possibility is that fear of the adverse consequences of ZIKV infection led to fewer conceptions or a greater number of pregnancy terminations in 2016.Rou tinely collected data are not yet complete enough to determine whether birth rates fell or abortion rates increased in 2016 (Section 6 in the Supple mentary Appendix).However, since any changes in the number of live births would be small, this hypothesis cannot be the principal reason why few cases of microcephaly were reported in the northeast region in 2016.Among these hypotheses, the first seems to be the most plausible -that is, both ZIKV and chikungunya viruses are important causes of GBS, but among the arboviruses circulating in Brazil, only ZIKV causes microcephaly and other neuro logic disorders after infection during pregnancy.However, the three possibilities are not mutually exclusive, and none can be ruled out with the present data.Further investigations are needed -aided by more sensitive and specific diagnos tic tools and the careful interpretation of surveil lance data -to clarify the causal links between arbovirus infections, GBS, and microcephaly in Brazil.