Meningococcal infections

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Meningococcal infections are caused by the bacteria Neisseria meningitidis (meningococci) and include meningitis and sepsis.

Infection is spread by direct contact with nasal and throat secretions.
People feel generally ill and have other, often serious symptoms, depending on the area infected.
Identifying the bacteria in a sample taken from infected tissue confirms the diagnosis.
Vaccination can help prevent meningococcal infections.
Antibiotics and fluids must be given intravenously as soon as possible.

More than 90% of meningococcal infections are

Meningitis: Infection of the tissues covering the brain and spinal cord (meninges)
Sepsis: Infection of the bloodstream (called meningococcemia when caused by meningococci)

Infections of the lungs, joints, eyes, and heart are less common.
In temperate climates, most meningococcal infections occur during winter and spring. Local outbreaks can occur, most often in sub-Saharan Africa between Senegal and Ethiopia. This area, which includes 26 countries, is known as the meningitis belt.
Meningococci reside in the throat and nose of some people without causing symptoms. Such people are called carriers. People often become carriers after outbreaks. However, infection usually occurs in people who have not been exposed previously to meningococci, rather than in carriers. Infection is spread by direct contact with nasal and throat secretions of an infected person (including carriers).
Most commonly infected are

Children aged 6 months to 3 years (see also Meningitis in Children)

Infections are also common among

Adolescents
Military recruits
College freshmen living in dormitories
Travelers to places where meningococcal disease is common
People with certain immune system disorders
People whose spleen has been removed or damaged
People who take eculizumab or ravulizumab (drugs that block a component of the immune system called the complement system)
Microbiologists working with meningococci

Meningococcal disease is more common among people with AIDS than among the general population. Other factors that may increase risk include getting a viral infection, living in a crowded household, having a chronic illness, and smoking or being exposed to cigarette smoke (passive smoking).
Outbreaks account for only a small percentage of cases and tend to occur among people who spend time or live in close quarters with others, for example, in dormitories or day care centers, and often involve people 5 to 19 years of age.