Ce que les dernières études disent du mode de transmission de la variole du singe

Ce que les dernières études disent du mode de transmission de la variole du singe

Smith Collection/Gado/Getty Images Although several studies have been published, understanding of the monkeypox epidemic is beginning to mature. And the idea of ​​transmission during sexual intercourse is clarified (microscopic photo taken from a clinical sample and digitally colored).

Smith Collection/Gado/Getty Images

Although several studies have been published, understanding of the monkeypox epidemic is beginning to mature. And the idea of ​​transmission during sexual intercourse is clarified (microscopic photo taken from a clinical sample and digitally colored).

HEALTH – This is a question that inevitably has an impact on how the world’s governments deal with the monkeypox epidemic: how is the disease transmitted? More than three months after the appearance of the first cases in Spain, 28,000 patients have been recorded worldwide, the first deaths have been reported and large-scale scientific studies are beginning to give their conclusions.

In recent days, three reference scientific publications, the Lancetthe British medical journal and the New England Journal of Medicine They have thus published some first analyzes that allow a better understanding of the profile of infected people, the symptoms they suffer and the way in which they could contract the disease.

bodily relationship, dominant transmission mechanism »?

All these studies draw the same typical portrait of the patient: an adult man who maintains homosexual relationships. A novelty regarding this already well-known disease in Africa, but which mainly affects children there. So, the study of the lancetcarried out in medical structures in Madrid and Barcelona, ​​​​says that 92% of the 181 patients are men who have sex with men compared to 8% of women (3%) and heterosexual men (5%).

Proportions found in the comments of Public Health France. In its August 4 report, the National Agency cited an overwhelming majority of men who have sex with men among patients (96% of cases in which sexual orientation is reported).

The other notable element of the study of the British magazine refers to the mode of transmission. Because if since the beginning of the epidemic scientists have been afraid to draw hasty conclusions and stigmatize homosexual men, researchers from the Lancet speak of a significant role of sexual intercourse in the transmission of the disease. This is in line with the recommendations of the World Health Organization, which has officially invited gay men to reduce their number of sexual partners.

Our study supports the idea that skin-to-skin contact during sexual intercourse is the dominant mechanism of transmission of monkeypox, with important consequences in the way the disease should be apprehended at the health level. “, we can read in particular in the study. Clearly, the idea that this is a sexually transmitted infection (STI) is not mentioned at this stage; it is above all about reducing prolonged contact with the skin, from mucosa to mucosa, which is particularly likely during sexual intercourse.

What about semen and sprays?

This observation is found in the areas of the body affected by physical symptoms: if all the patients in the survey presented skin lesions, 78% were affected in the anogenital area and 43% in the mouth. The same in Public Health France, which mentions 75% of patients with a ” genitoanal rash “, in addition to episodes of fever and muscle pain caused by the disease. The studies also cite rare complications, but never before observed: inflammation of the rectum or edema of the penis.

Consequently, the question arises as to the appropriateness of the measures taken to protect populations (particularly isolation). And the authors of Lancet say it clearly: The notable difference in viral load between lesion readings and throat readings warrants further study to better guide the decision whether or not to isolate people. “Currently, in France, sick people are forced to isolate themselves for 21 days as an example.

Thus, the airborne transmission trail loses credibility. In an interview with the magazine SciencesThe author of the study summarizes his team’s conclusions as follows: Viral load is very high in skin lesions and very low in the respiratory tract, so sexual transmission is likely to continue “.

However, many areas of darkness remain, which only in-depth studies in a larger sample of patients will shed light on. Starting from a hypothesis that, if not excluded, for the moment is anything but accredited by research, namely, that of transmission by sperm.

A doubt about the efficacy of the old vaccine

Another uncertainty relates to the effectiveness of an old vaccine. Indeed, in the study of Lancet18% of patients were vaccinated in childhood against smallpox, a virus similar to monkeypox and whose vaccines is it so is supposed to be effective). What makes the authors say that “ more research is needed to fully understand the protection offered by vaccination (Ancient, editor’s note) in the context of the ongoing epidemic That while noting, however, that this smallpox vaccination, widespread by the WHO in the late 1960s until the eradication of the disease, may go back decades, which could explain a drop in effectiveness.

Even with vaccination, researchers published by the lancet warn: Due to a short incubation period. (seven days on average, editor’s note) vaccination of risk groups before exposure to the disease is probably more effective than post-vaccination if health authorities want to control the epidemic. »

Last point raised by the data from the various studies: the link between being infected with monkeypox from another disease. Indeed, without knowing if it is a simple correlation or if there is a direct link, the study of the lancet notes that 40% of patients are also infected with HIV. In France, according to figures from Public Health France, they are 26% in the same case, and 5% of patients are immunocompromised.

See also in the HuffPost: In the face of monkeypox, why does the gay community care?


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