Each year, invasive meningococcal infections (IMD) affect around 500 people in France. Caused by the Neisseria meningitidisthis bacterial disease is usually characterized by meningitis, i.e. an infection of the meninges (it looks like a very solid cobweb that surrounds the brain and spinal cord) and/or sepsis (an infection blood or blood poisoning).
It is the most dreaded of all meningitis (1). In fact, one person in 10 who develops the disease dies from it and up to 25% of those who survive suffer lifelong serious sequelae. MDIs particularly affect infants under one year old, young children and young adults (15-24 years old). After more than two years of low incidence, in connection with the measures taken during the Covid-19 pandemic, the number of cases has been on the rise since this winter. Dr. Hervé Haas, head of pediatrics at the CHPG of Monaco explains the reasons for this rebound and reminds us of the importance of vaccination.
What is the situation of invasive meningococcal infections in France?
The number of cases of invasive meningococcal infection has been on the rise once more in a worrying way since October 2022 (Source Santé Publique France). With 84 cases of IIM declared last December, the incidence is at a high level, and exceeded the monthly peak generally observed later during the winter seasons preceding the Covid-19 pandemic (peak between January and March depending on the season). Unusually, peaks of type B meningococcal infection were observed in the Auvergne-Rhône-Alpes region and in Strasbourg. This increase does not only concern France. In November 2021, the English had also observed a peak in type B meningococcal infection, in adolescents, at a higher level than what was observed before the confinements. Another worrying finding: the cases of meningococcal infections W and Y, although infrequent, go back very clearly in France and Europe. Thus, in 2022, IMIs in France were mostly linked to serogroups B (53% of cases), Y (23%) and W (19%). Serogroup C was very much in the minority thanks to compulsory vaccination in infants (3%).
How can we explain this resurgence of meningococcal meningitis?
This situation can be explained by the barrier measures put in place during the Covid-19 epidemic. Travel restrictions and school closures have prevented the circulation of many viruses or bacteria (bronchiolitis, gastroenteritis, otitis, etc.). Thus, for two years, there were very few cases of meningococcal meningitis. However, not having been exposed to microbes and viruses during Covid has diminished the immunity of the population. This is also why the bronchiolitis epidemic was so strong this winter. In addition, the flu, which was particularly intense this year, was able to prepare the ground for bacteria – and therefore for meningococcal meningitis – by making the mucous membranes of the respiratory tract more permeable and fragile.
How to stop this progression?
The only way to avoid an epidemic rebound remains vaccination. On this point, France should change its vaccination schedule in the light of current epidemiology. The vaccination obligation of 2018 and relating to serogroup C has made it possible to considerably reduce the cases. But it’s not enough. The upsurge in IMIs encourages better communication regarding vaccination once morest meningococcal B, recommended for young children. It would also be necessary to broaden the population concerned by quadrivalent vaccines once morest serogroups A, C, W and Y. To date, they are not yet recommended by the French authorities. For example, the Netherlands, Belgium and the United States already offer to target adolescents with this quadrivalent vaccination. Another line of thought: establish a reminder of vaccines. Indeed, infants who are compulsorily vaccinated once morest meningococcal C will no longer have sufficient antibodies to be protected in adolescence.
The vaccine once morest meningitis B is not mandatory in France, although it is the most common infection. For what?
Because there would be no collective benefit. Indeed, it only protects the individual who has been vaccinated but does not prevent contamination (unlike the vaccine dedicated to serotype C). In France, we prefer to opt for a vaccination campaign in the event of an epidemic outbreak, even if this emergency solution is very expensive. We must not forget that it is not easy to set up an obligation to vaccinate. The French hesitation does not date from yesterday and obliges the authorities to move forward with caution. In the longer term, the objective would be to have a vaccine that can bring together all the meningococci. Scientists are working on this option.
1. Meningitis of viral origin is generally benign, those of fungal origin are rare but very severe.
Vaccination: who is concerned?
There are several serogroups of meningococcal meningitis. In France, this concerns B, C, W and Y.
Meningococcus C
Vaccination is compulsory and reimbursed for infants born from January 1, 2018 with a first dose at the age of 5 months. This vaccination is recommended for unvaccinated people up to the age of 24.
Meningococcus B
Vaccination is recommended and reimbursed for all infants, with a first dose at the age of 3 months. This vaccination is recommended for unvaccinated children up to the age of 2 years.
Recommendations
particular
There are also vaccines once morest serogroup B meningococcal infections and vaccines once morest serogroup A, C, W, Y infections. These vaccines are recommended for certain population groups (immunocompromised people or people at risk of infection) .
Transmission, diagnosis… 3 things to know regarding this bacterial infection
1 Transmission
Neisseria meningitidis bacteria are caught through the nose. It happens then that these bacteria overwhelm the body’s defenses and manage to infect the meninges, where they become dangerous. Bacteria can pass from one individual to another via respiratory secretions (saliva, sneezes, etc.)
2 Symptoms
The diagnosis is very complicated because the first symptoms often resemble those of a classic flu such as headaches or fever. IMIs can also result in serious signs, such as seizures, or generalized infection, also called sepsis. In the latter case, the bacterium reaches the bloodstream: this is the case with purpura, a skin condition characterized by the appearance of red or purple spots on the skin.
3 “Lightning” infection
The first symptoms can evolve very quickly during the first hours and result in symptoms of generalized infection. Between 5 to 10% of patients die within 24 to 48 hours of the onset of the first symptoms. Among the survivors, some people suffer serious long-term consequences: physical problems (scars, amputations), neurological or sensory problems (epilepsy, paralysis, deafness), cognitive disorders, anxiety…
