Immunization, Vaccines and Biologicals

Meningococcal meningitis

Meningococcal meningitis is a bacterial form of meningitis, a serious infection of the meninges that affects the brain membrane. It can cause severe brain damage and is fatal in 50% of cases if untreated.

Several different bacteria can cause meningitis. Neisseria meningitidis is the one with the potential to cause large epidemics. Twelve serogroups of Neisseria meningitidis have been identified, six of which (A, B, C, W135, X and Y) can cause epidemics. Geographic distribution and epidemic capabilities differ according to the serogroup.

In Africa, major epidemics have been occurring over the past 100 years. Most of them have been attributed to serogroup A and occurred in the African "meningitis belt”, a large area that spans sub-Saharan Africa from Senegal in the west to Ethiopia in the east. In 1996 to 1997, the largest epidemic in history swept across the belt, causing over 250 000 cases, an estimated 25 000 deaths, and disability in 50 000 people. Large epidemics recur in the meningitis belt on a regular basis.

Bacteria are transmitted from person to person through droplets of respiratory or throat secretions. The most common symptoms are a stiff neck, high fever, sensitivity to light, confusion, headaches and vomiting. Even when the disease is diagnosed early and adequate treatment is started, 5% to 10% of patients die, typically within 24 to 48 hours of the onset of symptoms. Bacterial meningitis may result in brain damage, hearing loss or a learning disability in 10% to 20% of survivors.

Several types of vaccine are available: polysaccharide vaccines — available in either bivalent (groups A and C), trivalent (groups A, C and W135), or tetravalent (groups A, C, W135 and Y) forms; and conjugate vaccines against group A and group C and tetravalent vaccines against groups A, C, W135 and Y.

In December 2010, a new meningococcal A conjugate vaccine was introduced nationwide in Burkina Faso, and in selected regions of Mali and Niger, with a total of 20 million persons 1 to 29 years of age vaccinated. Subsequently these countries reported, in 2011, the lowest number of confirmed meningitis A cases ever recorded during an epidemic season. Between October and December 2011, another 35 million persons were immunized across Mali and Niger (both countries have completed their nationwide campaigns) and three countries Cameroun, Chad and Nigeria launched their national campaigns. Four countries in the African meningitis belt are preparing for introduction of the vaccine in 2012 Benin, Ghana, Senegal and Sudan, while Cameroon, Chad and Nigeria are pursuing their nationwide campaigns.

It is hoped that all 26 countries in the African meningitis belt will have introduced this vaccine by 2016. High coverage of the target age group of 1-29 years is expected to eliminate meningococcal A epidemics from this region of Africa.

WHO position paper

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Last updated: 6 December 2011

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