Invasive meningococcal disease generally appears in one of three forms: meningitis, meningococcemia (blood infection), or pneumonia. The infection usually has an abrupt onset, with symptoms developing within 3–5 days. Even with proper antibacterial therapy, fatalities do occur. The over-all case fatality rate of invasive meningococcal disease is 9–12%. As many as 20% of individuals who contract meningococcal disease suffer serious, permanent damage, such as deafness, neurologic deficit, and limb loss.
Meningococcal meningitis, a severe, acute inflammation of the lining that surrounds the brain and spinal column, is the most common presentation of invasive meningococcal disease. Sudden high fever, severe headache, and a stiff neck comprise the common trio of diagnostic symptoms for meningococcal meningitis, and may be accompanied by increased sensitivity to light, vomiting, altered mental status (confusion, drowsiness), and joint pain.
Meningococcemia, a bloodstream infection, may occur with or without meningococcal meningitis and is marked by fever; hypotension; multiorgan failure; and a macular rash, which may be either pinpoint small (petechial) or consist of larger purple hemorrhages in the skin (purpuric).
Several Neisseria meningitidis serogroups are endemic in the United States. Current vaccines protect against four of five serogroups of meningococcal disease: A, C, Y, and W135. Group A is found mostly in the African meningitis belt, which spans from Ethiopia to Senegal. Overall, B, C, and Y each account for about 30% of cases; these numbers vary as much as 20% from year to year, as outbreaks are influenced by age and genetic factors. Type C is more common among older children and adults.