Major Epidemics of Meningococcal Disease 1971 to 1995
While groups B and C account for a large majority of cases in Europe and the Americas, group A is responsible for explosive epidemics in the African meningitis belt and Asia.
Source: Control of epidemic meningococcal disease, WHO practical guidelines, World Health Organization, 1998, 2nd edition, WHO/EMC/BAC/98.3
At any given time about 1 to 2 out of every 10 people have, or carry, meningococcal bacteria in the back of their throats or in their noses, but this number may be much higher during an epidemic. Most carriers remain in good health and do not develop the disease. However, in some cases, bacteria overcome the body’s immune system and cause disease.
All countries have cases of meningococcal disease, which primarily occur in young children, adolescents and young adults. Many countries experience endemic meningococcal disease at an annual attack rate of around 1 to 3 per 100,000 of the population.1 However, countries in sub-Saharan Africa experience ten-fold higher endemic rates of meningitis (annual attack rate of around 10 to 25 per 100,000 of the population), characterized by annual focal epidemics, and periodic explosive epidemic waves occurring every 5 to 12 years. These countries also see high attack rates in persons up to 30 years of age.2