2023-04-21 09:32:36
The situation has “nothing to do” with that of Strasbourg, assures Alexandra Thabuis, epidemiologist at Public Health France during a press briefing in Lyon. For a year and a half, seventeen cases of a specific variant of meningococcal B have been detected in a specific area of Auvergne-Rhône-Alpes. All the infected people, aged between 16 and 21, remained in intensive care for several days. And one of those young people died. A situation that pushes the Regional Health Agency (ARS) to launch an intense vaccination campaign. But in fact, what is meningococcus B? Why does it mainly affect young adults? And why does it circulate intensely in the region? 20 Minutes make the point.
What is Meningococcus B?
There are several groups of meningococci: C, B, Y and W. It is a bacterium found at the back of the throat, in the saliva. The most common infection when you catch this germ is called meningitis. It is a “rare” disease, usually between two cases per year in the region, but which can be “extremely serious” with “an almost systematic passage in intensive care”, alert Alexandra Thabuis. If not caught in time, it can be fatal (10% of cases result in death) or leave serious sequelae such as limb amputations.
Why does this strain of the bacterium circulate specifically in ten communes of Auvergne-Rhône-Alpes?
Several cases of meningococcal B have been identified in different areas in France. But the situation in Auvergne-Rhône-Alpes is “particularly worrying” and “different” from what is happening elsewhere. Alexandra Thabuis develops: “It is a new variant of group B, never before observed in France, which emerged in the region in 2021. On its own, it infected seventeen people (among sixty cases identified all strains combined) , aged between 16 and 21, in a year and a half, including one who died. »
The France Public Health Surveillance Committee then analyzed “groupings of outbreaks” and concluded that there was a phenomenon of hyperendemia, that is to say, a lasting and intense increase in incidence. “Two sectors had been identified, in Chambéry and in eastern Lyon, continues the specialist. The first zone is no longer hyperendemic, with no new cases for a year. But the stump continues to circulate in the other perimeter. We then identified ten municipalities, nine in Isère and one in the Rhône, where the risk of catching the disease is two hundred times higher among 15-24 year olds than in the rest of the region. »
Alexandra Thabuis underlines that there is “no explanation on the zone”. Meningococcal B variants can “disappear as they appear,” she explains. What is certain are the “ideal conditions” which the bacterium took advantage of to emerge. Among them, the Covid-19 pandemic which reduced exposure to the microbe for two years and brought with it a drop in immunity. But also, other respiratory infections, such as the flu very present this winter, which could have favored the invasive meningococcal B infection.
Why does this invasive meningococcal disease (IMD) B mainly affect young people?
“The meningococcal B germ is transmitted by droplets, by coughing or spittle, during close and prolonged contact”, indicates Bruno Morel, deputy director of health monitoring and alerts at ARS Auvergne-Rhône-Alpes.
And the many social interactions between 16 and 24 years would explain this intense circulation of the bacteria in this age group. “The cases identified had frequented festive places, which can promote the exchange of the microbe”, specifies Alexandra Thabuis. “We too would like to know, but we don’t yet have all the answers,” admits Bruno Morel.
The epidemiology specialist concludes: “The only way to protect yourself is to get the vaccine. The last two patients were not vaccinated and could have avoided the ten days spent in intensive care. The latter is recommended for all young people between 16 and 24 years old, it has no action on carriage and transmission but “simply on individual protection” to avoid serious forms.
Since January 2018, it is also strongly recommended for children under 4 years old, “because they are very fragile at these ages”, underlines the representative of Public Health France.
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