The largest meningococcal epidemic to date struck sub-Saharan Africa, affecting hundreds of thousands and killing tens of thousands. Local governments with the help of international aid organizations attempted to contain the epidemic, while preparing for future outbreaks.
Meningitis, or cerebrospinal meningitis (CSM), is an infection of the membranes that cover both the brain and spinal cord. Several bacteria cause CSM, but only Neisseria meningitidis (N. meningitidis, also known as meningococcus) gives rise to widespread epidemics. In the spring of 1805, Gaspard Vieusseux described the first meningococcal outbreak in Geneva, Switzerland. Meningococcal disease occurs worldwide, but Africa has been the continent most affected by recurrent, severe epidemics of meningitis.
Africa[09410]
Africa[09410]
Since the early twentieth century, numerous meningococcal epidemics have devastated sub-Saharan Africa and have recurred in a specific geographic location—a semiarid savanna between the fourth and sixteenth degrees north latitude. The area is characterized by minimal rainfall and by the harmattan—a dry, dusty wind originating in the Sahara. In 1963, Léon Lapeyssonnie appropriately named the area the African “Meningitis Belt.” The largest recorded meningitis outbreak struck this region in 1996-1997. It killed tens of thousands of people and affected hundreds of thousands of others.
Anton Weichselbaum cultured the meningococcus in 1887. Since then, twelve serogroups have been identified, of which A, B, C, and W135 have caused outbreaks of epidemic CSM. Characterization of the 1996-1997 bacterium has shown that N. meningitidis serogroup A clonal subgroup III-1 was at the origin of Africa’s largest epidemic. This strain first surfaced in Nepal in 1983-1984. It made its appearance again in India and Pakistan in 1985 and caused an epidemic during the 1987 pilgrimage to Mecca; returning pilgrims likely brought the strain to Africa.
In the two years preceding the 1996 epidemic, large meningococcal outbreaks occurred in Niger. In October of 1995, Nigeria saw a rise in meningococcal disease, and in the subsequent month the town of Jibia reached epidemic threshold, reporting more than 15 cases per 100,000 inhabitants during two consecutive weeks.
Sahelian epidemics typically occur during the dry season, which begins in December and continues through June, and come to an abrupt end at the start of the rain season. True to this trend, the 1996 epidemic began in January of that year. CSM cases were on the rise in early February and peaked between mid-March and mid-April when temperatures soared to 42 degrees Celsius (about 107 degrees Fahrenheit), and relative humidity dropped to 10 percent. The disease struck the poor, who lived in overcrowded, poorly ventilated housing. The population most affected comprised children from five to fifteen years of age, but the disease did not spare other age groups. Mortality was high: 22 percent of those affected died during the first ten weeks of the epidemic, about 15 percent during the second ten weeks, and close to 5 percent toward the end of the epidemic. Hearing loss, paralysis, mental retardation, and loss of limbs occurred in probably 10 to 20 percent of the survivors. In 1996, nearly 95 percent of all cases and fatalities occurred in Mali, Burkina Faso, Niger, and Nigeria.
The countries most affected by the epidemic organized a massive response with the help of the World Health Organization
The treatment of choice during West African epidemics has been the antimicrobial oily chloramphenicol. A single injection of the drug effectively treats the disease. Even though international aid organizations donated vast amounts of oily chloramphenicol during the 1996 outbreak, not enough was available, and many patients received ampicillin or penicillin, antibiotics that require frequent dosing over several days.
A massive immunization effort was launched in mid-March. After a minimal amount of training, health care workers were sent from village to village on horseback, bicycle, or motorcycle. Because of a limited supply of needles and syringes, vaccinators had to resort to the use of jet injectors. Incorrect use of the jet injector may also have led to the transmission of hepatitis and HIV between individuals. The impact of treatment and mass immunization became apparent by the second half of April, as fewer cases and fatalities were reported. The rain season started in early May and by the beginning of June, the 1996 outbreak ended.
The large-scale immunization efforts of 1996—Nigeria alone vaccinated 13.4 million people—had led to global depletion of meningococcal vaccine. It was feared that the epidemic would resurge in 1997, and this caused concern about the timely availability of sufficient quantities of vaccines and antibiotics. Under the auspices of the WHO, sixteen African nations met in October of 1996 in Ouagadougou, Burkina Faso, to discuss their anticipated needs. As a result of this meeting, the International Coordinating Group on Vaccine Provision for Epidemic Meningitis Control (ICG) was formed in January of 1997. The group’s primary mission was to assess the needs of affected countries and to gather and distribute necessary supplies.
As anticipated, the epidemic resurged in 1997. With the help of the ICG, there was timely delivery of vaccines, antibiotics, and so-called autodestruct injection materials. In 1997, no cases were reported in Nigeria, but the disease was rampant in Burkina Faso, Ghana, and Mali. Eritrea, Gambia, Mauritania, and Senegal saw no cases of CSM in 1996 but noted the presence of the disease in their countries the following year. The total number of cases reported to the WHO in 1996 reached 152,693 and included 16,213 deaths; in 1997, 60,861 people fell ill and 6,027 died. There was likely substantial underreporting of cases. Some patients succumbed to the disease before reaching a treatment center; others were never taken to health centers out of fear or ignorance. Health officials discovered graves where people had secretly buried their dead. The true number of affected and killed people can therefore only be estimated.
In the early years of the twenty-first century, meningococcal disease remained a significant public health problem in West Africa. A surveillance system for early detection of burgeoning epidemics had been put in place, however. Countries within the Meningitis Belt began to report their cases to the WHO weekly during the high-risk season and every other week during the remainder of the year. The enhanced epidemic surveillance system identified the emerging meningococcal serotypes and monitored the development of antibiotic resistance. Meningococcal polysaccharide vaccines have proven effective against N. meningitidis A and C. They do not provoke a protective immune response in children under the age of two, and the protection in older children lasts approximately three to five years. Mass immunization thus came to be used only when evidence arises of an impending epidemic.
The solution to recurring meningococcal epidemics in West Africa lies in preventive immunization of the at-risk population with a meningococcal vaccine that provides long-lasting protection in all age groups. Conjugate meningococcal vaccines have this ability. The Meningitis Vaccine Program (MVP), supported by the Bill and Melinda Gates Foundation, anticipates having a group A conjugate vaccine available for the Meningitis Belt by 2009. Mass vaccination of the high-risk population may soon bring an end to the feared sub-Saharan epidemics of meningococcal meningitis.
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“Enhanced Surveillance of Epidemic Meningococcal Meningitis in Africa: A Three-Year Experience.” Weekly Epidemiological Record (September, 2005): 313-320. Describes the efforts of the ICG for early detection and containment of emerging meningococcal epidemics. -
Greenwood, Brian.“100 Years of Epidemic Meningitis in West Africa: Has Anything Changed?” Tropical Medicine and International Health (June, 2006): 773-780. Contains detailed information about past African epidemics, the different meningococcal serotypes, and the immunization approach for the management of epidemic meningitis. -
Mohammed, Idris. “A Severe Epidemic of Meningococcal Meningitis in Nigeria, 1996.” Transactions of the Royal Society of Tropical Medicine and Hygiene (May/June, 2000): 265-270. Describes in great detail the extent of the 1996 epidemic in Nigeria and the efforts of both the Nigerian government and international aid organizations to contain it. -
Molesworth, Anna. “Where Is the Meningitis Belt? Defining an Area at Risk of Epidemic Meningitis in Africa.” Transactions of the Royal Society of Tropical Medicine and Hygiene (May/June, 2002): 242-249. Documents the southward extension of the Meningitis Belt initially described by Lapeyssonnie. -
“Response to the Epidemic Meningitis in Africa, 1997.” Weekly Epidemiologic Record (October, 1997): 313-318. Discusses the response of the ICG during the second year of the epidemic and the results of its interventions. -
Tikhomirov, Eugene. “Meningococcal Disease: Public Health Burden and Control.” World Health Statistics Quarterly (May, 1997): 170-177. Gives the number of meningococcal cases and deaths for each affected sub-Saharan country during the 1996-1997 epidemic.
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