Meningococcal infection is a severe, life-threatening bacterial infection caused by Neisseria meningitidis, also known as meningococcus. It most commonly presents as meningitis (inflammation of the membranes surrounding the brain and spinal cord) or bloodstream infection/sepsis. The disease can progress very rapidly — even within a few hours.
Meningococcus spreads through respiratory secretions, usually after close contact with an infected person, for example, by living in the same household, staying in close proximity for a prolonged period, or kissing. Some people may carry the bacteria without showing any symptoms.
The most common symptoms may include:
sudden high fever,
severe headache,
neck stiffness,
nausea or vomiting,
drowsiness, confusion,
a rash that does not fade when pressure is applied,
cold hands and feet, rapid breathing.
In infants and young children, symptoms may be different, such as irritability, weak persistent crying, poor feeding, or a bulging fontanelle.
If meningococcal infection is suspected, emergency medical attention must be sought immediately, as early treatment is critically important. Vaccines are also available that help protect against several types of meningococci.
Cause of meningococcal infection
The causative agent is the bacterium Neisseria meningitidis, for which 12 serotypes are known. Most meningococcal infections are caused by serotypes A, B, and C, and less commonly by serotypes Y and W-135. Epidemics in Africa are usually caused by N. meningitidis serotype A.
Mode of transmission of meningococcal infection
Infection occurs through direct contact when bacteria are spread through the air from the nose and throat of infected persons, patients, or asymptomatic carriers. The infection is not transmitted by insect vectors, and animals are not a reservoir of the infection.
Description of meningococcal disease
Most infections do not lead to clinical illness. The majority of infected individuals become asymptomatic carriers and serve as a reservoir and source of infection for others. In general, susceptibility to meningococcal infection decreases with age, although the risk of illness is slightly higher among adolescents and young adults. Meningococcal infection begins suddenly with severe headache, fever, nausea, vomiting, photophobia, neck stiffness, and various neurological manifestations. Death occurs in 5–10% of cases, even when prompt antibiotic treatment is administered in good medical facilities. Up to 20% of patients who recover from the infection usually experience long-term neurological complications. Meningococcal septicemia, in which the bacteria rapidly spread through the bloodstream, is a less common form of meningococcal infection characterized by circulatory collapse, hemorrhagic skin rash, and a high mortality rate.
Geographical distribution
Sporadic cases occur worldwide. In temperate climate zones, infection mainly occurs during the winter months. Localized outbreaks occur in closed institutions where many people gather, such as dormitories and military barracks. In Central Africa, in the area stretching from Senegal to Ethiopia (the so-called “meningitis belt”), large epidemic outbreaks are typical during the winter or dry season from November to June.
Risk of meningococcal infection for travelers
Overall, the risk is low. However, the risk is significant if travelers stay in places or attend events where many people gather, for example, during pilgrimages in the Sahel region within the meningitis belt. Localized outbreaks also occur from time to time among travelers, most often young people, in camps or dormitories. For more information on the risk to travelers, see Chapter 6.
Prevention of meningococcal infection
Vaccines are available against N. meningitidis serotypes A, C, Y, and W-135.
Precautionary measures
Avoid enclosed spaces where many people gather. After close contact with a person who has meningococcal infection, consult a doctor regarding the need for chemoprophylaxis.