How the Institut Pasteur contributes to the fight against meningococcal infections

Thanks to successive confinements and the implementation of barrier gestures, the Covid-19 period was a moment of respite in the transmission of invasive meningococcal infections. But since 2023, these infections, which peak during the winter season, have experienced an explosion in the number of cases, with 560 cases recorded in France in 2023, an increase of 72% compared to 2022, according to Public Health France.

And they seem increasingly difficult to detect, due to new strains Y and W, previously in the minority, which today correspond to half of cases of meningococcal infections. “ The unprecedented level of the number of these infections is partly explained by a decline in collective immunity and an increase in even more virulent strains. », Explains Muhamed-Kheir Taha, head of the national reference center (CNR) on meningococci at the Institut Pasteur, a French center dedicated to biomedical research.

Meningococcus, a public health problem

The unit headed by Muhamed-Kheir Taha, professor of microbiology, is dedicated to the study of invasive bacterial infections, including meningococcal infections. Meningococcus is a bacteria that lives in the human nasopharynx. If 10% of the population is an asymptomatic carrier, it happens that following a respiratory or ENT infection, the bacteria is found in the blood, or even crosses the blood-brain barrier to infect the cerebrospinal fluid. “ Invasive meningococcal infection is fatal in 100% of cases if left untreated. » recalls the professor.

The main difficulty for caregivers lies in successfully detecting the infection, transmitted by droplets. In the first nineteen hours of infection, the symptoms are not very characteristic and can be easily confused: fever, flu syndrome or abdominal pain. During this early phase, less than half of patients are sent to hospital. However, after this period, the symptoms can worsen very quickly, leading to septic shock or sometimes severe meningitis (death within 48 hours to 72 hours).

A crucial role in the detection of meningococcal infections

In the fight against this infectious disease, one of the Institut Pasteur’s challenges remains early diagnosis and vaccine prevention. “ It is crucial to diagnose quickly so that we can treat immediately », Explains the professor. To do this, the laboratory contributes to advancing research by monitoring, in conjunction with Public Health France, and diagnosing cases of infections recorded in the territory, in particular by sequencing the genome.

Muhamed-Kheir Taha’s team is also responsible for studying the resistance of different strains to antibiotics, using a rapid diagnostic test that it has developed. This test, which already has a proof of concept and “ was transferred to an industrialist for development “, should enable rapid patient care and fairer use of antibiotics. The issue is all the more important as half of the bacterial strains isolated are insensitive to penicillins, the most commonly used class of antibiotics.

On the occasion of the 18th edition of Pasteurdon, which is being held from October 9 to 13, the Pasteur Institute is warning of the increase in cases of invasive meningococcal infections and the antibiotic resistance with which it is associated. For Muhamed-Kheir Taha, “ vaccination remains the most effective means of prevention because it has a function of individual and collective protection “. Through its research work, the CNR participates in the development of national vaccination strategies. In France, vaccines are already available against strains A, C, W, Y, as well as B, the main strain responsible for acute meningitis. However, only vaccination against meningococcus C is obligatory.

But faced with the spectacular increase in cases of infections, the High Authority for Health revised its recommendations in July 2024. It recommends making the tetravalent vaccine against meningococcal ACWY compulsory in infants, and advises it in adolescents and young adults. She would also like to establish compulsory vaccination for serogroup B. Meningococcal infections today represent a real public health problem, which is worrying, even at the global level, with the WHO having made it a priority to “ defeat meningitis by 2030 ».