The worry grows. Cases of mpox, long called monkey pox, are exploding in the Democratic Republic of Congo (DRC). The World Health Organization (WHO) expressed concern on Friday about the risks of international spread. This infectious disease, which triggers a painful rash, pustules, swollen lymph nodes and fever, is not new. Endemic for a long time in several countries in central and west Africa, it had spread to 75 non-endemic countries in 2022, notably in Europe and the United States.
If the WHO had raised the alert in May 2023 while calling for people to remain vigilant, a new epidemic is therefore emerging in the DRC, carried by variant 1 of the virus. “We fear that there will be international transmission,” said Dr. Rosamund Lewis, a mpox specialist during a press briefing in Geneva. Which countries are affected? Why is variant 1 worrying? What to do to prevent the spread of the virus? 20 minutes make the point.
Which countries are affected?
The epidemic is spreading rapidly, as we have said, in the DRC. “More than 13,000 suspected cases” have been recorded in 2023, “more than twice the number of cases reported in previous years”, announced Doctor Rosamund Lewis. Among them, “more than 600 deaths”.
More generally, across the world, cases notified to the WHO have started to rise again. They went from around a hundred per month from June to August to “more than 1,000 per month” today, the doctor said. An outbreak of cases which also affects Asia, notably Japan, Vietnam, China and Indonesia. Cambodia reported its first case this week. WHO has also been informed of a suspected outbreak on a cruise ship that sailed in Southeast Asia.
Why is this variant 1 worrying?
The virus that spread to the United States and Europe in 2022 was mpox variant 2 (IIb). The current epidemic in the DRC is linked to variant 1. If the symptoms are approximately equivalent, “variant 1 is known to give more severe forms”, explains Jean-Daniel Lelièvre, epidemiologist and head from the infectious diseases department of Henri-Mondor Hospital in Créteil.
“Severe forms of mpox are also more fatal with this variant,” assures the epidemiologist. In Africa, the mortality rate of variant 1 is 10%, ten times more than variant 2. “The more severe forms of this variant can be explained by the more limited capacities of these countries to care for patients” , nuance the doctor.
Another concern of the WHO: its transmission. Until now, variant 1 present on the African continent was transmitted through contact with certain animals, notably rodents. “It therefore created limited epidemics which stopped quickly,” according to the professor. Except that, for the first time, sexual transmission among patients with variant 1 has just been observed. “The target population seems larger,” continues Benjamin Davido, infectious disease doctor, head of the infectious and tropical diseases department at the Raymond Poincaré Hospital in Garches. We are facing a more transmissible infectious agent. » The profile of those affected has indeed evolved. If in 2022, the vast majority of European patients were men, women are now also affected.
How to prevent its spread?
Epidemiological surveillance, strengthening of diagnostic capacities, appropriate case management, provision of effective vaccines, development of research to better understand modes of transmission… There are numerous avenues to prioritize to prevent the spread of the epidemic.
In France, vaccination against human smallpox was compulsory until 1979. Since then, only part of the target population affected by the variant 2 epidemic in 2022 has been vaccinated, mainly men who have sex with men. A small part of the French, therefore, especially since “the vaccine used during this campaign is effective but its coverage only lasts around two years”, recalls Jean-Daniel Lelièvre.
According to the two scientists interviewed, the whole question is therefore whether these vaccinations will be sufficiently effective to contain a potential epidemic resumption on French territory. “There are still a lot of question marks,” recognizes Benjamin Davido, “but this is the principle of a WHO alert. »
If the head of the department at Henri Mondor hospital believes that “we can fear an epidemic of mpox in France”, he recalls that “clinicians know the symptoms and are very careful”. And if France does not have a large stock of new vaccine against mpox, “it will order some if necessary”. So don’t panic. For the moment.