Meningococcal meningitis

Meningococcal meningitis is a serious infection caused by the gram negative diplococcus Neisseria Meningitidis. It is found worldwide but special climactic conditions in the arid Sahel Savanna belt of Africa predispose to periodic large-scale epidemics. The region extending from Senegal in the West to Ethiopia in the East is designated the "African meningitis belt". The meningitis outbreaks are seasonal and tend to occur in the dry season.

Within the meningitis belt, outbreaks of meningitis occur in epidemic cycles that last between 8 to 15 years. The length of the epidemic cycles are not the same for all countries e.g. Niger and Nigeria: 8-9 years, Burkina Faso: 10-15 years, Sudan: 10 years. (see Fig 2 below)

 

Figure 1.  Map of the meningitis belt

So far in 2001 meningitis has killed at least 670 people in Niger and over 570 in Burkina Faso and is threatening at least 16% of the population in Ethiopia, some 8.4 million people.  The seasonal outbreak in Niger is slowing down according to officials. According to the WHO in the past the last two epidemics in Ethiopia were preceded by an epidemic in Sudan two to three years previously and it was expected Ethiopia would soon be experiencing an outbreak of meningitis, given the outbreak of Sudan in 1999 (see the Figure 2 below)

This most recent outbreak is part of the continuing meningococcal meningitis pandemic, which began in 1996. It has so far resulted in more than 300,000 cases reported to the WHO.  The most affected countries have been Nigeria, Burkina Faso, Mali, Niger and Sudan.  The cause of the recent outbreaks in Africa is a new strain of Neisseria meningitidis (serogroup A clone III.1) first identified in the 1980’s that spread from Nepal and China. In 1997 15 countries reported meningitis outbreaks with an overall case fatality rate of 10.2%

Figure 2

Figure 2 shows the number of cases reported by countries in the meningitis belt over the past 30 years. It appears that the number and intensity of epidemics has been increasing, with a decreasing interval time between epidemics. According to the WHO “Endemic bacterial meningitis is a major public health problem that is often neglected.”  There is a need for increased national surveillance and monitoring programs in the affected countries. The factors responsible for the periodic outbreaks are not known, one school of thought is that it is related to the “herd immunity” of a population, particularly in the young.

50-60% of cases are found in children under 5 years old, but during outbreaks older children, teenagers and adults can be affected. Transmission is by airborne routes and epidemics occur when the climate is hot and dry and in confined, overcrowded living conditions. Direct contact and droplets from the nasopharynx (nose and throat) of infected individuals are the way the disease is spread. Case fatality rates are high ranging from 10% to 40%. The treatment of choice is a penicillin, Benzyl penicillin usually given by intravenous injection. Control and prevention can be accomplished by mass vaccination campaigns reaching 80% or more a population at risk to halt an epidemic.

Top

Last updated: August 22, 2002

Home About Us Health News Health Topics Country Profiles Links

All contents copyright © 2000, 2001 MEDILINKS.ORG. All rights reserved.