June 15, 2022

expert reaction to question about whether monkeypox has been detected in semen

There have been reports of possible monkeypox virus DNA detection in semen.

Dr Hugh Adler, Honorary Research Fellow, Department of Clinical Sciences, Liverpool School of Tropical Medicine, said:

“These reports¹ are important to investigate, and I’m very impressed that the Italian team were able to collect this data and communicate it with the public and scientific community so quickly.  Nonetheless, it’s early days, and importantly the detection of viral DNA in semen does not itself alone constitute evidence of sexual transmissibility.  The pre-publication report of “infectious virus” (presumably referring to a virus that replicates in cell culture) is an important additional piece of data.

“We already knew that monkeypox virus can be found in blood and urine – therefore it had the potential to be detected in genital secretions, either through sample contamination (any DNA present in urine may well still be detectable when a semen sample is produced) or genuine viral spillover into genital secretions.  The presence of viable infectious virus, if confirmed and replicated in further patients, would be more supportive of the virus genuinely being present in semen.

“Even if monkeypox were not present in semen, we can confidently state it would be transmissible during sex anyway, via close bodily contact and kissing, since it is present in the skin rash (which can often be present on the genitals, though obviously intimate contact is not limited to genital contact) and likely can spread short distances via respiratory droplets.  Sexual transmission would take on a greater significance, from a public health/outbreak management point of view, if infectious virus were to be present in semen either before or after the main monkeypox illness had resolved, when the patient was feeling better and considered themselves non-infectious.  This has been recognised for other viruses, but these viruses are genetically very different from monkeypox (e.g. RNA viruses like zika and Ebola).  Thus, we need long-term sampling to see how long monkeypox virus persists in human semen (the published Italian data relates to samples taken during acute illness) and whether any persistent virus is viable/infectious.  I would hope this research could be done during the current outbreak and inform public health practice.

“Clinical research describing patients developing monkeypox following sexual contact with someone who had fully recovered from monkeypox, where no other risk factor was present, would also be compelling – but I haven’t heard any such reports yet.

“For now, we don’t know if monkeypox can be transmitted sexually after the acute illness, and I am unaware of any public health reports to the contrary.  If data were to emerge suggesting sexual transmission from people who were otherwise asymptomatic, then we would have to look at our guidelines again.  For now, I would be following UKHSA/WHO advice.  For anyone having sex with a new partner, there are lots of reasons to practice safe sex and use condoms, regardless of whether monkeypox is in the mix or not.”

1 https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2022.27.22.2200421

Declared interests

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