“…And it is doubtful whether it ever will be proved, seeing that diverse animal poxviruses may exist, which, at least theoretically, could become candidates to the niche supposelly left vacant by that one which had adapted to the human organism. We do not, however, intend to dedicate these lines to that point, already debated by Candeias (1980) in this same periodical. Let us admit, then, the inexistence of the smallpox virus in nature, at least in so far as it is detectable.…”