Three months into the outbreak, experts are beginning to learn more about the disease, as 28,000 cases have been confirmed so far.
How is monkeypox transmitted? Are there any symptoms specific to the current outbreak? After several months of the epidemic, we are beginning to learn more, with confirmation: the current contaminations are mainly linked to sexual intercourse.
Three months after the start of the epidemic, nearly 28,000 cases have been confirmed worldwide and the first deaths are beginning to be reported. In this context, it is essential to better understand the disease to better fight it.
What is the profile of the patients?
Monkeypox has certainly been known for several decades in about ten African countries. But the current epidemic has many particularities, the first of which is the profile of the patients.
These are mainly adult men and maintaining homosexual relations, in contrast to what was observed in Africa, where the disease strikes many children in particular.
In recent weeks, three studies, published in the main reference medical journals – the British Medical Journal (BMJ), the Lancet and the New England Journal of Medicine (NEJM) -, drew a clinical picture of the current epidemic, even if it is only early work and carried out from a few hundred cases.
They confirm that the disease mainly affects men who have homosexual relations. In each study, they represent almost all of the patients.
How is the disease transmitted?
The predominance of this profile is not a surprise because, largely documented by initial observations, it has largely guided the recommendations of health authorities.
Above all, it leads to another question. Since the common point of the patients concerns for the moment their sexual activity, is the disease transmitted by the latter?
The subject is sensitive because some public health specialists fear stigmatizing homosexual people by targeting their sexual relations.
But recent studies are clear. “Our work supports the idea that bodily contact during sexual activity is the dominant mechanism of transmission of monkeypox” in the current epidemic, summarizes the study of the Lancet, carried out in several Spanish hospitals. This conclusion is based in particular on the fact that the viral load was much higher in the skin lesions of the patients than in their respiratory system.
The observation therefore seems to undermine the idea, put forward by some researchers, that airborne transmission also plays an important role in contamination.
However, this does not mean that the disease is transmitted through semen. The hypothesis is not excluded but current research is far from proving it.
What are the symptoms ?
The three studies also confirm that the current epidemic is distinguished by its symptoms.
They “differ from those observed in populations affected by previous epidemics” in Africa, thus summarize the BMJ study, whose observations were made in the United Kingdom.
Certainly, two central elements of the disease remain largely present: an attack of fever, sometimes accompanied by muscle pain, and lesions on the body, which then turn into scabs.
But the details vary and the question is surely linked to that of transmission because, in recent patients, certain physical manifestations appear associated with contamination during sexual intercourse.
In each study, the lesions are often concentrated on the anus, penis and mouth. Added to this are complications very little observed until now: inflammation of the rectum or edema of the penis.
What about the severity of the disease? Nearly 40% of the cases were the subject of complications, according to the study of the Lancet, and a fifth were hospitalized according to that of the NEJM. However, in the latter, “no serious complication has been identified”, tempers this last work, evoking “reassuring” data.
What do we still not know?
Even if this work makes it possible to better understand the disease, many questions remain unanswered. This is particularly the case with the effectiveness of vaccines. The study of Lancet shows that a significant proportion (18%) of patients had received an anti-smallpox vaccine, which is supposed to protect against monkeypox.
But the delay between vaccination and the disease, sometimes several decades, can explain this lower protection.
Finally, it remains to be seen whether there is a greater risk when you have another disease. Nearly half (40%) of the patients studied in the Lancet were thus infected with HIV. But it is impossible to know if there is a direct link or a simple correlation.