Apart from the wide spread spraying of toxic pesticides?
quote from google search(zika causes) -Since it can’t possibly be Zika with a majority of the affected babies having no virus, let’s look at a real possible cause then: A new TDAP shot Brazil made mandatory at the beginning of 2015, which coincides with perfect timing with a whole bunch of newborns being born with defects. That’s right, in late 2014 the Brazilian minister of health announced a new Tdap shot to become mandatory for all expectant mothers as soon as Brazil received it, which ended up being in early 2015. No zika found in a majority of messed up babies, but ALL MOTHERS WITH MESSED UP BABIES GOT THAT NEWLY FORMULATED SHOT WHILE PREGNANT. Troubleshooting 101, the answer is obvious.