Does the practice known as MBP cause HSV-1 in infants?

Question

To introduce this question, there is an ongoing lawsuit in NYC about the religous practice of "metzitzah b’peh".

From the city's info page about it:

Health Department investigations of newborns with herpes virus between 2000 –2011 have shown that 11 infants contracted the herpes virus when mohelim, or ritual circumcisers, placed their mouths directly on the child’s circumcision wound to draw blood away from the circumcision cut. Ten of these infants were hospitalized, at least two developed brain damage, and two babies died.

From the city's official guide to MBP:

Between 2004 and 2011, the Department learned of 11 cases of laboratory-confirmed herpes simplex virus infections in male infants following circumcisions that were likely to have had direct oral suction. Ten of these infants were hospitalized, at least two developed brain damage, and two babies died.

And from an article supporting the plantiffs:

Notably, the Health Department’s conclusion that MBP carries significant risk of dangerous infection is not at all supported by the evidence. In the plaintiffs’ court papers challenging the regulation, a number of distinguished experts strongly challenge the validity of the City’s position. As Dr. Daniel S. Berman, Chief of Infectious Diseases at the New York Westchester Square Hospital, states in his legal affidavit, “In my professional opinion, the evidence does not show that MBP has ever resulted in transmission of HSV-1.”

From another article supporting the plantiffs:

But the facts are indisputable. “No case of neonatal herpes anywhere in the world has ever been proved, through definitive DNA fingerprinting, to have resulted from metzitzah b’peh,”the plaintiff brief attests.

My question is simple; is there a health risk from MBP, given the available evidence, or not? Are the facts "disputable" (which is a moot point. They clearly are, at least by NYC and the CDC).

Edit: here's a Google search that has all the relevant links from NYC's website:https://www.google.com/search?q=site:nyc.gov+mbp+hsv-1 (I don't want to track down all the links.)

Edit: I just wanted to add two more links, one in defence of MBP, and the paper referred to in an answer.

Answer 1

Let's bracket out religious controversy by asking: Can a person contract herpes from direct contact between mouth and genitals? The answer is a definite yes.¹ The situation is only exacerbated by the age of the child and raw contact with an open wound.

A meticulously-documented meta-analysis on religious practices in the International Journal of Infectious Diseases, examines MBP to find:

The largest case series by the Centers for Disease Control and Prevention (CDC) was published in 2012, wherein they highlighted 11 cases of HSV-1 after confirmed or probable oral–genital suction from 2000 to 2011 in New York City. 10 of 11 cases were hospitalized and unfortunately two cases were fatal. Six patients had mucocutaneous lesions, two had central nervous system involvement, and three had dissemination to visceral organs. In 2004 twin boys born via cesarean to a mother without evidence of HSV infection during childbirth underwent metzitzah on the eighth day of life. Afterwards, both neonates developed fever and vesicles on their abdomen, buttocks, and genitalia that contained HSV. One of these infants later developed disseminated infection and died. These cases prompted an investigation by the New York City Health Department, which discovered that a year prior, a case of neonatal HSV infection after metzitzah by the same mohel had also led to vesicular lesions. After these cases were reported the New York City Health Department set up surveillance, which uncovered eight more cases of HSV-1 after probable or confirmed oral–genital suction. The discovery of these cases was facilitated by a 2006 mandate in the New York City Health Code that infants less than 60 days old with a diagnosis of herpes infection be reported. When laboratory confirmation of HSV-1 or untyped HSV was obtained there was further investigation to determine if ritual oral–genital suction was performed. The authors calculated the estimated relative risk of neonatal herpes to be 3.4 times greater after direct oral–genital suction compared to those who did not.

These 22 cases provide evidence that metzitzah with direct oral–genital contact can transmit HSV-1 infection. The temporal relationship where all infants presented within 2 weeks of the ceremony is consistent with the typical incubation period of HSV; the isolation of HSV-1, a pathogen typically transmitted via oral contact, and negative serologies or clinical manifestations of herpes in most of the mothers all suggest an association. Additionally, the finding that some of the mohels’ saliva tested negative for HSV is not surprising since shedding of HSV is sporadic and can be found in asymptomatic individuals, as demonstrated by Hatherley et al. and Douglas and Couch.15 Finally the location of HSV-1 on genitalia suggests that it was likely transmitted via direct contact.²

1. Center for Disease Control and Prevention, "Genital Herpes, CDC Fact Sheet."
2. Pellerin, James, and Michael B Edmond. “Infections Associated with Religious Rituals.” International Journal of Infectious Diseases 17, no. 11 (November 2013): e945–948.