Meningitis is an infection of the envelopes surrounding the brain, the meninges, caused by several types of viruses, bacteria and fungi. Meningococci (another name for the bacterium Neisseria meningitidis) are the major causes of acute meningitis. Meningococcal infections have a high death rate.

The annual incidence of meningococcal infections in France is 600 people per year with a seasonal upsurge (winter and spring). Early antibiotic treatment is the main measure available to save lives and reduce complications. A law in force since January 1, 2018 makes vaccination compulsory before the age of 18 months in France.

Meningitis are infections of the meninges, these thin membranes that surround the central nervous system (brain and spinal cord). These infections can be related to a virus, bacteria or fungus. The most serious are meningococcal infections. They are caused by bacteria of which there are several subgroups.

In France, the most frequent infections involve bacteria of type B and C. Meningococcal meningitis is associated with a high mortality rate (up to 50% if it is not treated) and a high frequency (greater than 10%) of severe sequelae. The current incidence of meningococcal infections is 1 to 3 cases per 100 inhabitants in industrialized countries. Meningococci are the only bacterial species capable of causing epidemics of meningitis.

Who is concerned ?

Meningococcal meningitis usually occurs in infancy (before 5 years) and in young adults (before 25 years). The bacteria are often transmitted by healthy carriers. This bacterium is fragile and is not easily transmitted outside of close contact and promiscuity with an infected person, through droplets of saliva or coughing, sneezing, kissing.

These infections are not transmitted as easily as a cold or the flu. For reasons not fully understood, meningococcus can spread through the bloodstream and then reach the meninges. The average incubation period is 2-10 days. The period of contagion of the infected person is effective up to 24 hours after the start of antibiotics.

Meningococcal meningitis is found all over the world, but it is in the ‘meningitis belt’, which stretches in sub-Saharan Africa from Senegal in the west to Ethiopia in the east, that the burden of disease is the heaviest. About 30 cases are still reported each year in this area.

An infectious syndrome is often associated with a meningeal syndrome with different manifestations including:

• a more or less high fever;
• severe headache (headache), nausea or vomiting;
• intolerance to light (photophobia) or noise (phonophobia);
• stiff neck (absent in infants);
• lethargy (feeling sluggish), fatigue, severe muscle aches;
• agitation, convulsion, even coma;
• bleeding purplish red spots under the skin (purpura).

The progression to serious complications such as shock, coma or death can be very rapid (within a few hours). Between 9 and 12% of people with meningococcal infection die from it despite appropriate antibiotic treatment. Among those who survive, up to 20% suffer from after-effects (deafness, brain damage, mental retardation, etc.).

The appearance of red or purplish spots under the skin (purpura) gradually spreading is a criterion of the severity of the infection. This complication, called “purpura fulminans” causes fatal septic shock one in three times.

In infants, signs of meningitis may be absent. The fever, the refusal to eat, the weakening of the general condition or a “slack” posture are sometimes the only clues.

The diagnosis is made by performing a lumbar puncture (sample of cerebrospinal fluid). Its analysis makes it possible to identify the presence of infectious agents and the responsible bacteria. This diagnosis is essential for the initiation of antibiotic treatment.

The treatment of an invasive meningococcal infection of any type is based on prescribing antibiotics through the veins or intramuscularly, and as soon as possible after the onset of symptoms. Meningococcal meningitis C requires emergency hospitalization. Very often, faced with symptoms suggestive of meningitis, antibiotics and corticosteroids are administered urgently before waiting for the results of the lumbar puncture, even if the treatment is adapted thereafter.

The earlier the meningitis is treated, the better the outcome and the less risk of sequelae. Conversely, the absence of rapid treatment can cause damage to other parts of the central nervous system (encephalitis) or to the whole body (sepsis).

Among the possible sequelae and complications, we can mention deafness, visual disturbances up to blindness, delayed speech, delayed walking, visual disturbances or attention. The infection may have destroyed some tissue, resulting in amputations of the legs, arms or fingers.

The meningitis vaccine has been successful in reducing the risk of a heavy epidemic as a consequence on human health. Vaccination against serogroup C meningococcal infections is the most common in France. It has become mandatory for children born after January 1, 2018. Infants must be vaccinated from the 5th month and receive a booster in the 12th month. Vaccination is recommended for unvaccinated people up to the age of 24 depending on the risk of severe infection.