This is the first case in France, after alerts in several European countries and as far as the United States. The Directorate General of Health, confirmed this Friday morning the presence of a case of monkey pox in Ile-de-France. He is a 29-year-old man with no history of travel to a country where the virus is circulating, who was taken care of and, in the absence of seriousness, is isolated at his home.
Since May 14, confirmed cases of infection by this virus, rare but circulating in West and Central Africa, have been reported in several countries around the world such as the United States and Canada. In Europe, the United Kingdom has less than ten, Spain more than forty have been identified in Sweden or Italy. Benign, but rare on the Old Continent, this disease challenges health agencies and raises fears of an epidemic resurgence.
India Leclercq, researcher at the Institut Pasteur’s emergency biological intervention unit and teacher at Paris Cité, works specifically on this virus, also called Monkeypoxvirus. She makes the point for L’Express.
L’Express: what do we know about this virus?
India Leclercq: It is endemic in West Africa and Central Africa. Which means that it circulates quietly in these regions. Since the 2000s, there has been an increase in the number of cases in certain regions of Africa, mainly in Nigeria and the Democratic Republic of Congo. Its circulation has accelerated, we now know that we have had more cases in the last ten years than in the previous forty years.
It is a virus of the orthopoxvirus group, and a viral zoonosis which is transmitted to humans by animals such as rodents and monkeys. It is called monkeypox because it was first detected in primates, but the reservoir of the virus is thought to be in rodents. It causes relatively mild infections and most people recover within a few weeks. There may be some mortality, which varies depending on the virus. There are indeed two “clades”, or branches, genetic, of this virus. One that circulates mainly in West Africa and another in Central Africa, we know that the branch originating in Central Africa is more pathogenic and virulent than that of the West.
What is this lethality you speak of?
For the clade of West Africa, mortality does not exceed 1%, on the other hand for that of Central Africa it is rather around 8 to 10%. But serious cases are relatively rare and most often this lethality is mainly linked to problems of malnutrition or secondary bacterial infection or immunosuppression. These are problems that can be encountered in these regions of Africa where the healthcare systems do not allow good patient care, and as this disease causes skin lesions this can lead to secondary bacterial infections.
But I insist, in general the disease is relatively benign. The symptoms observed are headaches, muscle aches, the appearance of lumps in the lymph nodes, forms of prostration in children, and lesions which may appear on the face and may extend to the rest of the body. body.
The first confirmed case in France has been formally identified, has this been done in your laboratories?
No, we intervene in an emergency, outside working hours, but the CHUs have the technical means to establish this kind of diagnosis, the Biomedical Research Institute of the Armed Forces, which hosts the CNR Orthopoxvirus, can also do it.
Should this first confirmed case in France alert us?
What seems quite unusual to me is this dissemination of cases all over Europe and even elsewhere since they also have them in the United States. Until now, we observed relatively localized epidemics, and this time the number of cases is more diffuse, it is something a little new. It remains difficult to give an explanation for this in the immediate future, it will be necessary to investigate further but a priori we should be able to limit the spread of the virus. It is still too early to tell whether this may lead to a wider outbreak.
Is this rise in cases surprising? Could we expect an epidemic?
It’s quite unusual to have cases in Europe. Their constant and so close increase has, it seems to me, little or not been observed previously. But this virus is on the radar of the World Health Organization, which has called it “emerging”, and therefore needs to be monitored. A recent modeling study has shown that it does have epidemic potential. We could therefore expect to see an increase in cases. On the other hand, the number of secondary cases currently observed is more surprising, even if it is still quite limited. In 2003, we had a big epidemic of Monkeypoxvirus in the United States and Canada, with 47 people affected, which shows that this kind of wave is not totally unprecedented. The epidemic is known to be endemic and active in parts of Africa and the first case in the UK has been well documented: it is a person who returned from Nigeria, a country in which the virus circulates more than elsewhere.
But beyond the geographical origin, there were then human-to-human transmissions at the local level, which means that the following cases are not imported cases. But what reassures us is that we have already had this type of transmission and that they can remain localized or even stop on their own. So we have to wait to see what will happen. The good news is that we have the diagnostic means to identify new cases fairly quickly.
Can the appearance of these cases in Europe be linked to a resurgence in these African countries?
Probably since we are witnessing a strong resurgence of Monkeypoxvirus infections in these African countries. The most likely hypothesis is a cessation of vaccination against the smallpox virus, which also protected against other orthopoxviruses, responsible for infection in humans.
We vaccinated a lot against smallpox until the beginning of the 1980s, then from there, when this disease was declared “eradicated”, we gradually stopped vaccination campaigns. We therefore probably have an immunity in the population which has decreased and that is also why we find cases rather in young people who have not been vaccinated against the smallpox virus at all.
The other explanation for this resurgence can be found on the side of these populations more frequently exposed to the animal reservoir. And this is a recurring problem with emerging diseases, because these people are increasingly in contact with wildlife due to globalization, deforestation, cultivation, etc. And so that can also partly explain the increase in the number of cases. Finally, there are also more diagnoses of this disease.
The cases identified in England mainly concern homosexual or bisexual people. How to explain this? Could they be particularly at risk?
We cannot say for the moment that the homosexual community would be more at risk in this case, and until now, no sexual transmission for the monkeypox virus had been described. I will be careful not to draw hasty conclusions, based on the still fragmented data that we have.
Do we know of treatments or vaccines against this disease?
There is no specific treatment for monkeypox virus, but there is one that has been approved in the United States for smallpox, which could be used for monkeypox. And then there is the generic vaccine against smallpox, which has proven itself since this disease has been eradicated thanks to vaccination, which is also nearly 85% effective against Monkeypoxvirus. Which means that if ever this virus took a little more scale, we would have the means to fight it.