Monkey pox: how far can the epidemic go?

At first glance, it is a health scenario that is reminiscent of others, and not necessarily the most pleasing: a few scattered cases first, then a number of contaminations which, day by day, begins to grow and ends by being counted in the hundreds, even in the thousands.

This scenario is the one followed for the moment by the epidemic of monkeypox, this disease causing rashes. At the beginning of May, it reached Europe after having been confined to Africa for a long time.

“We didn’t expect it to get so big”

But what exactly does the rest of the scenario foresee? How high will the number of cases go?

The question arises since, for the moment, the dynamics of the epidemic show no signs of slowing down. On the contrary. In France, the number of cases has thus gone from 17 at the end of May to 1,567 as of July 21, 2022 . Half of these cases were recorded in Île-de-France.

The number of cases of monkeypox in each French region, as of July 21, 2022. | WEST-FRANCE INFOGRAPHIC

Monday July 26, François Braun, the Minister of Health, even indicated that the bar of 1,700 cases had been reached.

Read also: TESTIMONIALS. “Sick with monkey pox is the worst suffering I have ever known”

“We did not expect it to take on such magnitude, says Christophe Batéjat, Deputy Head of the Biological Emergency Response Unit at the Institut Pasteur. Until now, monkeypox epidemics were much less important. At the start of this epidemic, we were counting on 200 or 300 cases in France… ”

The virus for the moment confined to a well-identified community

But, if this increase in the number of contaminations is therefore, in certain aspects, spectacular and unprecedented, the fact remains that it responds to a certain logic.

First because “epidemics are always one step ahead”, recalls Mathieu Revest, professor in the infectious diseases department of the Rennes University Hospital. In effect, “the first cases are not detected and the diagnoses are not obvious to make immediately”, he recalls. At the start of an epidemic, the virus therefore always spreads quietly.

Read also: Monkey pox. Symptoms, transmission, vaccination… Where is the epidemic?

Moreover, this time, the monkeypox virus, which is transmitted by close contact, “happened (in Europe) to people who had a lot of very close contact with a lot of people”summarizes Mathieu Revest.

This created large initial clusters, especially in part of the homosexual community “extremely sexually active”, recalls Christophe Batéjat. In the end, the virus therefore spread quietly and very quickly.

An epidemic that can be contained

Paradoxically, if this favored the initial spread of the virus, the fact that the epidemic affects this community more particularly may suggest that control of the epidemic will be facilitated.

“It is a community that is aware of the risks associated with sex with multiple partners without the use of protection, and which is therefore completely ready to put in place preventive measures”explains Matthieu Revest. “And the LGBT associations have been very proactive” about it, he says.

Moreover, recalls Christophe Batéjat “The high level of case detection is linked to the fact that this population is aware of sexually transmitted infections and accustomed to self-control. ».

In fact, a scenario where tens of thousands of cases would appear in France remains ” very unlikely “according to Mathieu Revest.

“It is an epidemic that must be taken head on to avoid a tidal wave, but it is a safe bet that the measures put in place or which could be put in place in the future will make it possible to control the things “, assures the researcher from Rennes.

Among the measures mentioned by the Rennes researcher: the vaccination of people at risk, which should accelerate in the coming days with the future establishment of a vaccination center in Île-de-France.

Doses of monkeypox vaccine vials at a vaccination center in Chicago, Illinois, USA, July 25, 2022. | ERIC COX/REUTERS

However, even if the future dynamics of the epidemic remain difficult to estimate, in particular because of this “rather unusual community transmission”Christophe Batéjat considers “possible that we will exceed 3,000 cases” in France.

Will we also have to “live with the virus”?

The number of contaminations should therefore continue to climb but, in the end, “We have good hope of controlling this transmission and getting rid of the disease”, says the researcher from the Institut Pasteur. So no need to learn “to live with the virus”. Unless…

“What could be a problem is that there is an animal reservoir that is created, because there was none in Europe until then, he recalls. This is what happened in the United States, where there are now indigenous cases. But despite everything, we remain with very moderate epidemics in the United States. »

An international public health emergency, really?

So, given the researchers’ optimism about a controllable and minimally lethal disease, how can the WHO have declared monkeypox to be a “public health emergency of international concern” ?

“The WHO is perfectly in its role”says Matthieu Revest. “There is indeed an international spread of a disease hitherto confined to a continent” which legitimizes this placement, “but that does not predict the seriousness of things”.

Nevertheless, recalls Christophe Batéjat, this decision “has good and bad sides”: “It risks stigmatizing and provoking reactions vis-à-vis this community, but it has the advantage of pushing countries to adapt their surveillance to this virus and its circulation. » Monitoring which, all the same, will remain necessary for some time to come.

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