Meningococcal infections are caused by Neisseria meningitidis (meningococci) and include meningitis and bloodstream infections.
More than 90% of meningococcal infections are infections of the space within the tissues covering the brain and spinal cord (meningitis—see Meningitis: Acute Bacterial Meningitis) or of the bloodstream (sepsis—see Bacteremia, Sepsis, and Septic Shock: Bacteremia). Infections of the lungs, joints, 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 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. Infection usually occurs in people who have been exposed to meningococci rather than in carriers. Infection is spread by direct contact with nasal and throat secretions.
Children aged 6 months to 3 years are most commonly infected. Infections are also common among adolescents, military recruits, college freshmen living in dormitories, people with certain immune system disorders, and microbiologists working with meningococci.
Most people feel very ill.
Meningitis can cause fever, headache, red rash, and a stiff neck and, in infants, feeding problems, a weak cry, and sluggishness.
Bloodstream infections may cause a rash of red or purple spots. A severe infection may cause low blood pressure, a tendency to bleed, and dysfunction (failure) of many organs (such as the kidneys and liver).
Overall, 10 to 15% of people who are treated die of meningococcal infections. More than half of people with severe bloodstream infections die. Of people who recover, 10 to 20% have serious complications, such as permanent hearing loss, mental retardation, or loss of fingers or toes.
Rarely, infection develops more slowly and causes more gradual, mild symptoms.
Doctors suspect meningococcal infection in people who have typical symptoms, particularly if symptoms occur during an outbreak. To confirm the diagnosis, they take samples of blood or other infected tissues or do a spinal tap (lumbar puncture) to obtain a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid). The samples are examined under a microscope to check for and identify bacteria. The samples are also sent to a laboratory, where the bacteria can be grown (cultured) and identified. The polymerase chain reaction (PCR) technique, which produces many copies of a gene, may be used to identify the bacteria's unique genetic material (DNA).
The bacteria may also be tested to determine which antibiotics are effective (a process called susceptibility testing).
A meningococcal vaccine is available in the United States. Vaccination is recommended for the following:
Family members, medical personnel, and other people in close contact with people who have a meningococcal infection should be given an antibiotic by mouth (such as a few doses of rifampin or one dose of ciprofloxacin or levofloxacin) or by injection (such as one dose of ceftriaxone) to prevent infection from developing. Meningococcal vaccine is also given (in addition to antibiotics) to people in close contact with a person who has a meningococcal infection.
People are usually admitted to an intensive care unit and given antibiotics and fluids intravenously as soon as possible. Corticosteroids may be given to children or adults who have meningitis.
Last full review/revision September 2008 by Matthew E. Levison, MD