The Mpox epidemic, or “monkey pox”, is worrying. In particular a new variant, clade 1b. Appeared for the first time in September 2023 in the mining town of Kamituga, in South Kivuin eastern Democratic Republic of Congo (DRC), it has spread to neighboring regions and countries. Apparently more contagious, this variant has adapted to human-to-human transmission. It is transmitted during sexual contact and circulates among both men and women, while the 2b variant, responsible for the 2022 epidemic, had mainly affected homosexual men with multiple partners.
The World Health Organization (WHO), which convened its emergency committee on Wednesday, August 14, has just triggered its highest level of health alert at the international level in the face of the resurgence of cases. The international agency indicates that there are several Mpox epidemics – with different variants – in progress. It supports the other “public health emergency” alert launched on Tuesday, August 13 by the African Union health agency. Antoine Gessain, professor at the Pasteur Institute and specialist in this disease, nevertheless believes that there is no need to worry about a pandemic affecting Europe… if the necessary measures are implemented.
L’Express: what is Mpox and where does it come from?
Antoine Gessain: It is a zoonosis, a human disease transmitted by an animal, probably a squirrel that lives in Central and West Africa. It was first detected in 1970. The clinical signs are fever, swollen lymph nodes, and skin rashes that sometimes, in moderate forms, resemble chickenpox. There are two variants of the virus, the first, clade 1, is present in Central Africa, while the other, clade 2, circulates in West Africa.
Both clade 1 and 2 viruses are responsible for the classic clinical forms that cause small intrafamilial epidemics, particularly affecting children, in remote areas, far from good medical infrastructure, sometimes even in conflict zones. It is the youngest, mainly due to bacterial superinfections, malnutrition and dehydration, who pay the heaviest price for the disease in these conditions (5 to 10% lethality).
In 2017, researchers discovered a new clinical form of the disease in Nigeria. It spread to Europe, affecting almost exclusively homosexual male populations. Following exclusive human-to-human transmissions, the virus mutated and a new variant, clade 2b, emerged. There were approximately 100,000 cases and 200 deaths worldwide, but this pandemic was contained. What we are facing today is an epidemic due to a new variant, clade 1b, which was detected in September 2023 in South Kivu, a province of the DRC.
Should we be worried?
What is worrying is that this new variant, epidemic in the region, has spread to the DRC and several neighboring countries. Indeed, the clade 1b virus has been described in Rwanda, Burundi, Kenya and Uganda. A scientific study, published in June in Nature Medicinereports several hundred cases – but there are probably many more today – and specifies that the virus is transmitted primarily through sexual intercourse within at-risk populations, particularly among mine workers and local sex workers. Clade 1b has therefore adapted, through successive human-to-human transmissions, a bit like 2b in the 2022 pandemic, except that this time, women are also affected.
The mining region of South Kivu, in the east of the Democratic Republic of Congo (DRC).
© / Google Maps/L’Express
There has also been a greater number of cases of Mpox in Central Africa for the past two or three years, particularly in the DRC. Since 2024, there have been between 12,000 and 15,000 cases and 500 victims, 50% of whom are children. But the majority seem to be infected with the clade 1 virus (now called 1a), responsible for the classic disease that mainly affects children and families. And this increase is probably linked to the fact that we know more about the disease and that diagnoses are better made. There are therefore two epidemics: one caused by the classic form (clade 1a) and another linked to clade 1b. It is the latter that worries the WHO.
Can this new variant reach France and Europe?
A significant increase in cases in Central Africa is feared due to a complex local situation. In fact, this increase is, unfortunately, already underway. In the DRC, the epidemic has reached the large city of Bukavu [NDLR : plus d’un million d’habitants, à quelques kilomètres du Rwanda et du Burundi]. It has also spread to neighbouring countries. Therefore, the risk that clade 1b will spread cannot be ruled out.
However, so far, no one has been able to really demonstrate that the clade 1b virus is more transmissible. Perhaps it is more easily transmitted because local conditions in South Kivu mean that there is more sexual transmission, particularly through young adults and sex workers? Or is it the virus itself that is more transmissible? We don’t have the answer yet.
Then, it must be remembered that out of the 100,000 cases of the 2022-2023 pandemic, there were “only” between 150 and 200 deaths. Almost all of the victims in Western Europe, the United States or Brazil were suffering from HIV, and received little or poor treatment for this disease. In Central Africa, there are problems of malnutrition, poverty, lack of care and a population already very affected by HIV. Above all, we managed to defeat the 2022 pandemic thanks to vaccines, treatments, by isolating patients and contact cases. If clade 1b arrived in the West, I have no doubt about our ability to fight this virus effectively. Overall, we are prepared to deal with this kind of situation.
What strategies should be implemented?
Human, logistical and financial resources must be increased in Central Africa in order to reduce the local epidemic and its spread to neighboring countries. In short, do what we did in 2022: improve care, isolate clinical cases and contact cases, monitor and inform the various populations at risk.
Furthermore, it is essential to make vaccines more available, which is not yet the case, while in France we managed to vaccinate tens of thousands of people in 2022 and 2023. Finally, drugs, such as tecovirimat, must be distributed effectively to the populations most at risk. If this is done quickly, the current epidemic will diminish in the affected regions.
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