Some years ago I've read it's responsible for something like 1/3 or 1/5 of all hepatitis cases in israel, can't find the source I'm not even sure about the number but it's a thing, however I've found this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608492/ >>Neonatal Herpes Simplex Virus Type 1 Infection and Jewish Ritual Circumcision With Oral Suction: A Systematic Review The medical component of a bris involves the surgical removal of the foreskin. Historically, this excision was followed by a step called “metzitzah b'peh,” in which the mohel sips wine, orally extracts a small amount of blood from the wound, and then expels the mixture from his mouth. The wound is then bandaged and additional ritual steps follow. Religious authorities have provided various explanations for the purpose of orogenital suction, ranging from ancient concepts of physiology and medicine [1–3] **to esoteric spiritual insights on the bris ritual [3, 4].** "esoteric spiritual insights"... Hmmmmmmmmm.... https://failedmessiah.typepad.com/failed_messiahcom/2012/03/why-metzitzah-bpeh-must-be-banned-part-2-678.html >>The earliest mentions we have of MBP being anything other than a health measure come in the 16th century – 1300 years after the codification of the mishna quoted above – and primarily come from **kabbalists** who saw the act of metzitzah b'peh as a rectification of the sin of Adam HaRishon, the Torah's first human being and an indispensable part of the circumcision ritual itself. **The kabbalah these men studied was primarily based on the Zohar, a 13th century Spanish forgery falsely attributed to Rabbi Shimon Bar Yochai, who lived in Israel just before the codification of the Mishna. The Zohar is laced with Aramaic words and grammar of a much later period, and traces of Spanish – a language that did not exist in the 2nd century CE – can be seen, as well.** **The forger, a rabbi no less,** claimed to have found this previously unknown work of Bar Yochai, and went on to make his living selling copies of it. When asked by a group of rabbis sent to investigate the provenance of the work, the forger's wife freely admitted that her husband wrote it. (Don't call me a heretic for writing this because it is essentially **the position of Rabbi Yaakov Emden and several other 17th century rabbis** and it has been confirmed by modern historical research and linguistics, as well. Some other haredi rabbis take the position that some of the Zohar is authentic, but most of the book is made up of material added much latter. Hasidim and the current crop of non-hasidic haredi leadership takes the position that the Zohar is the holiest work next to Tanakh, the Hebrew Bible.) Nevertheless, the book was judged to be holy, and it made its way into the accepted canon of Jewish scholarship. By the 16th century it had begun to openly influence halakha. And when the hasidic movement was founded, it was based on mysticism derived from the Zohar and the kabbalist works that grew from it. And because some of those works see MBP, metzitzah done specifically with the mouth, b'peh, as a rectification of Adam's sin, many hasidic rebbes – **including even Chabad rebbes – adopted the view that MBP had been included in the circumcision ritual for that reason. The health benefits of MBP were only secondary. ... The plot thickens...