Epidemic Control of Meningitis in Africa

Emergency mass vaccination campaigns are difficult to implement quickly and effectively.

Photo: Monique Berlier

In order to determine whether meningitis has reached alert or epidemic level, the World Health Organization revised regional guidelines in 2014, based on weekly disease incidence:

  • Alert threshold
    • Populations 30,000 – 100,000: 3 cases per 100,000 persons in 1 week
    • Populations <30,000: 2 cases within 1 week or a higher incidence than in a non-epidemic year
  • Epidemic threshold    
    • Populations 30,000 – 100,000: 10 cases per 100,000 persons in 1 week
    • Populations <30,000: 5 cases within 1 week or doubling of incidence in a 3-week period

As soon as an epidemic is identified, an investigation team is sent to the area to confirm the pathogen that is causing disease and, if appropriate, initiate an emergency response. Epidemic response includes management of cases and mass vaccination of the entire population, provided that vaccine supplies and administrative support are available. If resources are limited, it may be necessary to restrict vaccination to the age groups most at risk.

In theory, a rapidly implemented vaccination campaign—one that begins within three to four weeks of an epidemic onset—will prevent about 70 percent of cases. However, in practice, it is difficult, if not impossible, to launch a reactive campaign so rapidly, as vaccines arrive in limited quantities and often too late to do much good. In fact, studies have found that reactive mass campaigns have limited results and may only prevent approximately 23 percent of cases and 18 percent of deaths.