Infections caused by meningococcus

Invasive infections caused by meningococcus (meningitis and septicemia)

Invasive infections caused by meningococcus (meningitis and septicemia), given that they are serious and meningococcus is transmittable, have to be detected immediately.  Moreover they involve adapted treatments and disease prevention (prophylaxis) and also a check of the epidemiological risk. Such infections happen in France and in Europe in a sporadic way. In other words, only a few individuals isolated from each other are concerned.
In France 800 cases are recorded each year – the majority during winter. Those infections mainly concern children and teenagers.  The World Health Organization (WHO) estimates that there are 500 000 cases of invasive infections caused by meningococcus each year worldwide.

Those infections are epidemic in sub-Saharan Africa during the dry season (from January to May). Dozens of thousands of cases are registered in each country.

The vaccines which are currently available act on the bacterial envelop which recovers meningococcus. Thus these vaccines depends on the serogroup. Vaccines against serogroups A, C, Y and W135 exist but there is no vaccine against meningococcus belonging to serogroup B. The envelop B is not much immunogenic because this serogroup is similar to certain structures on our neural cells.

However advances have to be mentioned:

-          The development of the recombinant vaccines (made of bacterial proteins under the envelop) is currently studied to act on the clones of meningococcus B. This is a way to avoid the problem of the envelop B.

-          A new combined vaccine against the clones belonging to serogroup A (MenAfriVac) should be launched in Africa between 2009/2010 and 2015 for 250 millions of individuals aged from 1 to 29 for less than 0,50 $ per vaccine. This vaccine embodies the hope of putting an end to epidemics due to the clones of serogroup A in sub-Saharan Africa.

-          The Vaccinations Technical Committee (VTC) regularly assesses the use of the combined vaccine  against meningococcus belonging to group C depending on the evolution of the epidemiological data. This recommendation to use or not the vaccine depends on which country of the European Union you are in: in certain countries there is no recommendation, in other countries vaccination concerns a defined group of people or even appears in the vaccination schedule. In France, this vaccine is currently recommended for the persons who are in contact with a case of invasive infection due to meningococcus-serogroup C and during vaccination campaigns which aim at preventing grouped cases. (Source: Pasteur Institute, February 2009)

Main serogroups of meningococcus