Meningitis, septicemia: invasive meningococcal infections jumped by 72% in 2023

Méningites, septicémies : les infections invasives à méningocoques ont bondi de 72 % en 2023

Invasive meningococcal infections (IIM), responsible for meningitis or septicemia, have increased significantly in France in 2023, according to Public Health France.

The agency highlights an unprecedented resurgence of IIM Y and W, serogroup Y being very virulent with a mortality rate more than twice as high as groups B and Y.< /p>

French Public Health publishes, this Wednesday, April 10, the official figures for invasive meningococcal infections (IIM) in 2023. The end of 2022 was marked by an early and very high peak in cases of IIM with 89 cases as of December. The number of cases then remained at high levels throughout the winter. In 2023, 560 IIMs were declared, i.e. 72% more than in 2022.

The resurgence of cases is marked "by a sharp increase in IIM W and Y to levels never observed before, marking important changes in the epidemiology of IIM", Public Health France alert. The highest mortality rate is associated with serogroup W (19% or 31 deaths), much higher than deaths associated with serogroups B (7% deaths) and Y (8% deaths).

Purpura fulminans, the most serious form of IIM

Meningococci are bacteria that can cause serious illnesses such as meningitis or septicemia. These can be fatal or leave significant after-effects. This is a family whose serogroups B, W, Y and C are the most common in France. They are transmitted through the air or saliva. Their transmission, between humans, requires close and prolonged contact.

Purpura fulminans is the most serious form of invasive meningococcal infection. Meningococcus causes widespread infection of the blood and organs. Purplish-red spots may appear on patients' bodies. This is a life-threatening emergency. In 2023, purpura fulminans was reported in 18% of IIM cases.

A drop in immunity involved ?

In total, 44% of IMDs were linked to serogroup B (240 cases), 29% to serogroup W (160 cases) and 24% to serogroup Y (130 cases). Group C IIMs have become rare with only 5 cases reported. "Among infants under 1 year old and children aged 1 to 4 years, IIM B remained in the majority, representing almost 60% of cases but slightly lower than in 2022 (67%), while IIM Y and W represented a growing share of cases with 41% of cases among those under 5 years old (compared to 30% in 2022). Among those over 15 years old, IIM W and Y increased with age. The elderly were the most affected by IIM Y", further details Public Health France.

How to explain such an upsurge in IIMs ? The decline in immunity after the confinements of the "Covid years" is advanced but also the return of respiratory viruses, which can promote invasive bacterial infections.

The need for broad vaccination coverage

These data pushed the High Authority for Health (HAS) to review the vaccination strategy. In an opinion published in March, it recommends compulsory vaccination for infants under 1 year of age concerning serogroups A, C, W and Y and vaccination of 11 – 24 years. It also recommends compulsory vaccination of infants under 1 year old against serogroup B.

These results "underline the challenge of achieving high vaccination coverage in the groups targeted by meningococcal vaccination recommendations" , abounds Public Health France.

Note: a meningococcal infection is most often not serious and leads to a respiratory or ENT infection (angina, otitis, sinusitis&hellip ;). "However, in rare cases, bacteria can end up in the blood and eventually cross the blood-brain barrier to infect the spinal fluid, leading to edema and inflammation meningé", explains the Pasteur Institute.