Meningitis – inflammation or infection of the membrane covering the spinal cord and brain – is most commonly caused by a virus or a bacteria. While meningitis caused by either organism is serious, viral meningitis is typically not a severe illness and is rarely fatal. Bacterial meningitis can be quite serious depending on the organism – particularly if caused by S. pneumoniae or N. meningitidis.
Meningococcal disease – infection caused by the bacteria Neisseria meningitidis – usually causes meningitis or meningococcemia (blood stream infection) which can develop very rapidly. It is considered a very serious public health emergency and is fatal in about one in 10 patients. Prophylaxis is recommended for close contacts.