The New England Journal of Medicine found the virus in the seminal fluid in 29 of 32 tested samples.
New research points to sex between men as the primary mode of transmission fueling the global monkeypox outbreak.
It turns out that claims that skin contact is probably much less of a risk factor.
Studies in several journals have been published in recent weeks, which offer a great deal of insight into the various ways a recent strain of monkeypox virus is transmitted, including findings and data published in:
- An article from The Lancet.
- An article from the New England Journal of Medicine studying cases in 16 countries.
- An investigation from the UK Health Security Agency.
- Surveillance from the European Center for Disease Prevention.
Correct identification of the mode of transmission is critical in determining the proper set of precautions to promote to stop the spread of the disease.
A growing body of evidence supports that sexual transmission, particularly through seminal fluids, is occurring with the current MPX outbreak,” said Dr. Aniruddha Hazra, medical director of the University of Chicago Sexual Wellness Clinic, referring to monkeypox and to recent studies that found the virus in semen.
Consequently, scientists told NBC News that the Centers for Disease Control and Prevention and other public health authorities should update their monkeypox communication strategies to more strongly emphasize the centrality of intercourse among gay and bisexual men, who comprise nearly all U.S. cases, to the virus’ spread.
On Aug. 14, Dr. Jeffrey Klausner, an infectious disease physician at the University of Southern California, and Dr. Lao-Tzu Allan-Blitz, a resident physician in global health at Brigham and Women’s Hospital in Boston, published an essay on Medium in which they reviewed the science supporting the argument that during the current outbreak, monkeypox is largely transmitting through anal and oral intercourse between men.
“It looks very clear to us that this is an infection that is transmitting sexually the vast majority of the time,” Allan-Blitz said.
Proctitis, an inflammation in the lining of the rectum, was more likely in individuals who reported anal receptive sex, while nearly all of those who presented with ulcerative tonsillitis reported oral receptive sex, found Oriol Mitjà, PhD, of University Hospital Germans Trias i Pujol in Badalona, Spain, and colleagues in a study published in The Lancet.
“Lesion swabs showed the highest viral loads, which, combined with the history of sexual exposure and the distribution of lesions, suggests close contact is probably the dominant transmission route in the current outbreak,” the group wrote.
The findings were consistent with a viral load more than three orders of magnitude higher in lesion samples than in respiratory samples.
“Strikingly higher viral loads in lesion swabs than in pharyngeal swabs should be further investigated to guide the decision on whether respiratory transmission is relevant and respiratory isolation at home is necessary,” the researchers added.
Their study enrolled 181 human monkeypox virus-infected patients from three sexual health clinics in Madrid and Barcelona. Of these patients, 166 identified as gay, bisexual, or men who had sex with men (MSM), and 15 identified as heterosexual men or heterosexual women.
The New England Journal of Medicine found the virus in the seminal fluid in 29 of 32 tested samples, and a previous smallpox vaccination was not 100% preventative.
That study reported complications such as conjunctival lesions, acute kidney injury, and a self-limiting myocarditis, which were not observed by the researchers in Spain.
Mitjà and co-authors noted that 32 individuals in their cohort (18%) acquired monkeypox infection despite a smallpox vaccination history, which “warrants further investigation to better understand the protection provided by vaccination in the context of the current outbreak.”
Limitations of the study included no testing of other bodily fluids such as blood and semen, “although it is still unclear whether these bodily fluids contribute to monkeypox virus transmission,” [Dimie Ogoina, MD, of the Niger Delta Teaching Hospital in Bayelsa, Nigeria] pointed out.
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