A group of rabbis are clashing with New York City health officials over the safety of an ancient circumcision ritual. Three rabbis and three Jewish groups asked a federal court yesterday to block enforcement of a new regulation requiring written parental consent for a rite called “metzitzah b’peh,” in Hebrew, which city health experts said can spread infection and has killed two children since 2004. During the ritual, the person performing the circumcision attempts to cleanse the wound by sucking blood from the cut and spitting it aside. The saliva contact puts the infant at increased risk of herpes simplex, a virus that is carried harmlessly by a large majority of adults but that can be deadly in newborns. New York City’s Health Department said it has documented 11 cases of the infection since 2000 among children believed to have undergone the ritual. Ten required hospitalization. Two developed brain damage. Two died.

The deaths prompted some doctors to call for the practice to be banned entirely, but the city’s Board of Health adopted a compromise approach last month. Under the new rule, mohelim performing the circumcision would be required to inform parents that the city believed the procedure was dangerous and have them sign a consent form. No one would collect the forms, and the mohelim would be required to keep them for a year before destroying them.