Neisseria meningitides bacteria, in most cases serogroups A, B and C, less commonly, Y and X. Serogroup W-135 is of increasing concern.
Transmission occurs by direct person-to-person contact and through respiratory droplets from patients or asymptomatic meningococcal carriers. Humans are the only reservoir.
Nature of the disease
As a rule, endemic disease occurs primarily in children and
adolescents, with highest attack rates in infants aged 3–12 months; in
meningococcal epidemics, rates may rise also in older children and
Meningococcal meningitis has a sudden onset of intense headache, fever, nausea, vomiting, photophobia and stiff neck, plus various neurological signs. The disease is fatal in 5–10% of cases even with prompt antimicrobial treatment in good health-care facilities. Among individuals who survive, up to 20% have permanent neurological sequelae. Meningococcal septicaemia, in which there is rapid dissemination of bacteria in the bloodstream, is a less common form of meningococcal disease, characterized by circulatory collapse, haemorrhagic skin rash and high fatality rate.
Sporadic cases are found worldwide. In temperate zones, most cases occur in the winter months. Localized outbreaks occur in enclosed crowded spaces (e.g. dormitories, military barracks). In the “meningitis belt” of sub-Saharan Africa, a zone stretching across the continent from Senegal to Ethiopia, large outbreaks and epidemics take place during the dry season (November to June). Recent reports of group Y meningococcal disease in the United States, and outbreaks caused by serogroup W-135 strains in Saudi Arabia and sub-Saharan Africa, particularly Burkina Faso, Chad and Niger, and serogroup X in Burkina Faso and Niger, suggest that these serogroups may be gaining in importance.
Risk for travellers
The risk of meningococcal disease in travellers is generally low. Those travelling to industrialized countries may be exposed to sporadic cases, mostly of A, B or C. Outbreaks of meningococcal C disease occur in schools, colleges, military barracks and other places where large numbers of adolescents and young adults congregate.
Travellers to the sub-Saharan meningitis belt may be exposed to outbreaks, most commonly of serogroup A and serogroup W135 disease, with comparatively very high incidence rates during the dry season. Long-term travellers living in close contact with the indigenous population may be at greater risk of infection.
Pilgrims visiting Mecca for the Hajj or Umrah are at particular risk.
Avoid overcrowding in confined spaces. Following close contact with an individual suffering from meningococcal disease, medical advice should be sought regarding possible chemoprophylaxis and vaccination.