At first glance, these two sets of case reports may semen-ly suggest that monkeypox can be a sexually transmitted infection (STI). After all, case reports published on June 2 in the journal Eurosurveillance and described in a pre-print posted June 6 on Research Square described how monkeypox virus DNA was found in the semen of five different patients. However, calling monkeypox an STI based solely on these seminal reports would be a premature declaration. There just isn’t enough evidence so far to turn what’s been known about monkeypox on its head just yet and call it an STI. However, the World Health Organization (WHO) is looking further into these case reports.
Before this current monkeypox outbreak, which has affected at least 1,285 people across 28 different countries to date, according to the WHO, there was no real hard evidence that monkeypox can be sexually transmitted specifically. As I described for Forbes last month, the main suspected modes of transmission have been close contact and handling contaminated objects. However, once word spread that sex raves in Europe may have served as super-spreader events for this outbreak, people started looking more closely at genitals.
Speaking of genitals, the June 2 publication in Eurosurveillance detailed what happened to four men in Italy, all in their 30s, who caught the monkeypox virus and ended up developing lesions in their genital and/or anal regions. Prior to their recent encounters with the monkeypox virus, all four did have encounters with other pathogens known to cause STIs. Three of them had had syphilis. Three had had viral hepatitis. Two had tested positive for HIV and received antiretroviral therapy, and the other two were on antiretroviral pre-exposure prophylaxis (PreP) while testing negative for HIV.
During the first half of May 2022, all four men had had condomless sexual intercourse with various male partners while traveling. Three of the men had traveled to a mass gathering event in Gran Canary island (GCI) and one had traveled for sex work. Then subsequently, all four ended developing monkeypox with lesions appearing in each of their genital or anal regions or both. Testing of all four patients’ genital or rectal lesions did reveal the presence of monkeypox virus DNA, which wasn’t surprising. So did testing of two patients’ nasopharyngeal swabs, one patient’s blood, and one patient’s saliva. There were some poopy positives as well with the stool samples from two different patients revealing the presence of monkeypox virus DNA. Ah, but here’s the finding though that is keeping the WHO and others on the ball, so to speak: PCR testing found monkeypox virus DNA in semen samples from three of the four patients.
The pre-print uploaded on Research Square described similar findings with two men in Germany. One was a 26-year-old male sex worker, who had previously tested positive for HIV and was already on antiretroviral therapy. A little over a week after having sexual intercourse with another man on May 9, this man showed up at a sexually transmitted disease (STD) outpatient clinic in Munich, Germany, complaining of four days of fever, malaise, mild joint pain, muscle pain, and back pain, headache, difficulty swallowing, and white spots on his tonsils. Two days later, several papular skin lesions emerged on his trunk, extremities, and head.
The second man was 32-years-old and had had unprotected intercourse with another man during the first half of May. On May 19, he visited his primary care physician complaining of a fever, fatigue, and a cough. Two days later, he had a groin problem: the lymph nodes in his groin were growing larger. He also was suffering from anal pain and multiple skin lesions (vesicles) all over the trunk of his body. In other words, he had some junk on his trunk.
Both men ended up being transferred to the isolation ward at the Munich Clinic Schwabing. There they had various body parts and body fluids tested for the presence of monkeypox DNA. Doctors found such DNA in both patients’ oral lesions and blood. And like three of the patients in Italy, these two also had monkeypox virus DNA in their semen.
Before you go nuts about these findings, keep in mind several things. First of all, the report from Germany is still a pre-print and not a peer-reviewed publication. If you can upload a video of your cat plotting to take over your house on the Internet, you can upload a pre-print as well. So take anything said in the pre-print with a fanny pack of salt.
Secondly, these case reports comprise only a handful of semen cases. That’s handful in terms of it being a relatively small number. It’s not clear what percentage of the over 1285 monkeypox cases in this outbreak may have had monkeypox virus DNA in their semen. That would require a much more massive semen study.
Third of all, finding monkeypox virus DNA in semen is not the same as finding live monkeypox virus in semen just like how finding Chris Hemsworth’s biceps in your bedroom would not be the same as finding all of Chris Hemsworth there. When there is enough virus in the blood, it is possible that some virus fragments can end up in different parts of the body, including the testicles and thus whatever comes from the testicles, so to speak. Moreover, even if some live virus ends up in semen, the levels may not necessarily be high enough to infect others.
Before you say, “but how about the sex raves,” remember that just because you get infected with a virus during sex doesn’t necessarily mean that it’s an STI. Presumably during sex your entire body at some point would be in close physical contact with the other person’s entire body. It would be tough to have sexual intercourse with someone in a room while your head, torso, and extremities remained in a different separate room, regardless of how well-endowed you may claim to be. To qualify as an STI, a virus has to be passed specifically through an act of sex rather than just being close to each other.
Nevertheless, all of this does merit further investigation and more studies as it raises the possibility of the monkeypox virus perhaps, possibly, maybe being sexually transmitted. With human monkeypox infections being relatively rare since the first documented case appeared in 1971 up to the start of this year, there may not have been enough cases over the years to know enough about how the virus may behave under different circumstances or change over time.
The authors of the pre-print did note that laboratory studies in mice have shown that the vaccinia virus, a virus similar to the monkeypox virus, may have some affinity for testicular and ovarian tissue. Of course, there are presumably differences between your genitals and mouse genitals. Plus, having sex is not the same as conducting a mouse experiment in a laboratory. Beakers, test tubes, and cages are typically not part of sex. Well, at least, beakers and test tubes are not. So, again, there is just not enough evidence right now to call monkeypox an STI. The WHO will likely look further into the why, what, and how of these case reports.
In the meantime, all of this shouldn’t change monkeypox precautions. You shouldn’t say, “OK, since monkeypox is not officially an STI, it should be fine having sex with that person covered with pus-filled lesions.” On the flip side, don’t somehow believe that the virus can be transmitted from one person to another only when they have sex. For example, don’t believe that it’s OK to directly touch someone else’s mysterious fluid-filled lesions as long as the intent isn’t sexual.