Meningococcal disease includes meningococcal meningitis and meningococcaemia. Meningococcal meningitis is a severe bacterial infection of the membrane that covers the brain and spinal cord. Meningococcaemia is an infection of the blood. Meningococcal meningitis and meningococcaemia are caused by the bacterium Neisseria meningitidis (N. meningitidis), which is known as the meningococcus and infects humans only.
N. meningitidis bacteria are found in the nose and throat without causing disease. Most people exposed to N. meningitidis do not become ill. Only a few people develop illness, which might be associated with genetic, immune, societal or physical factors.
Signs and symptoms of the diseases include high fever, headache, vomiting, stiff neck and a rash. Sensitivity to light, sleepiness and confusion may also occur. The symptoms may appear anytime between 2 to 10 days after exposure, but usually within 3 to 4 days. The disease might progress in a severe form of permanent brain damage, hearing loss, kidney failure, loss of arms or legs, or chronic nervous system problems. The fatality rate among those who develop meningococcal disease ranges from 10% to 15% even with prompt medical intervention.
Meningococcal disease can occur at any age; however, it is more common in infants and children under five. Teenagers and young adults aged 15–24, household contacts of a person known to have had this disease, immunocompromised people, and people traveling to parts of the world where meningococcal disease is prevalent are also at increased risk of contracting the disease.
The meningococcus germ is spread by direct close contact with nose or throat discharges of an infected person. A person with meningococcal disease may transmit the disease beginning several days before becoming ill, until the bacteria are no longer present in discharges from the nose and throat. The bacteria do not survive well outside the human body.