New York City health officials have gone to court to stop a rabbi from performing a type of ritual circumcision they believe may have led to the death of a baby boy from herpes.

The baby was one of three infants found to have contracted herpes simplex virus after being circumcised by Rabbi Yitzchok Fischer, who used his mouth to draw blood from the infant’s wound, a traditional Orthodox practice during the bris, or religious circumcision.

The complaint filed by the department of health in Manhattan Supreme Court asked that Fischer submit blood samples to be tested for the herpes virus and no longer engage in the specific practice until an investigation is completed.

The court papers, filed on December 22, were reported on by the Daily News on Wednesday

“Rabbi Fischer is still performing circumcisions, but he is complying with the court’s direction,” his lawyer, Mark J. Kurzmann, told Reuters on Wednesday. Kurzmann described Fischer as a London-trained, “internationally known” mohel, or someone who performs circumcisions.

Ten days after Fischer circumcised twins last October, one died of herpes and the other tested positive for the virus, according to the court papers. A third baby circumcised by Fisher was later found to have also tested positive for herpes, health officials said.

An affidavit submitted to the court by Dr. Susan Blank, assistant commissioner of the health department, said Fischer had performed about 350 Jewish circumcisions in the area.

Blank noted that the herpes virus, which is common in adults and often causes lesions known as “fever blisters” or “cold sores” is easily transmitted but not usually a serious illness in adults. In newborn infants, however, herpes can cause severe illness and may be fatal, she said.

Kurzmann suggested the infants could have contracted the infection some other way.

“Rabbi Fischer is cooperating fully with the city’s investigation in order to determine the true sources of the infection,” Kurzmann said.