Symptoms of meningococcal meningitis and meningococcemia
Generally meningococcus infects the nasopharyngeal mucosa non-symptomatically, but sometimes it can cause acute nasopharyngeal symptoms that can lead to the meningitis, bacterial septicemia, or both. In the case of meningitis, bacteria enter the meninges and infect the cerebrospinal fluid, causing the meninges to swell, thereby affecting the entire central nervous system. After an incubation period of 2 to 10 days, acute symptoms may appear, including high fever, severe headache, vomiting, nausea, stiff neck, purpura, photophobia, and sometimes delirium, seizures or comma. Petechia is also often present but not always. Diarrhea or respiratory symptoms are less common. Local infection symptoms, including endocarditis, myocarditis, pericarditis, arthritis, or ophthalmitis, can sometimes occur. Very rare cases of sepsis or pneumonia are observed

The meningococcal infection including sepsis, called meningococcemia, has a higher mortality rate than meningococcal meningitis, however has lower risk of neurologic disorders. The bacterium produces a pathogenic endotoxin. 100 to 1,000 times greater in amount compared to most of other bacteria. It multiplies in the bloodstream and sheds lots of toxic material which directly affects many organs including the heart, leading to subsequent decreased blood pressure and circulation. Hemorrhage takes place in some vessels and major organs can be damaged. Symptoms of meningococcemia are similar to those of influenza at the initial stages. First symptoms include fever, nausea, myalgia, headache, arthralgia, chills, diarrhea, stiff neck and malaise. Later symptoms include septic shock, purpura, hypotension, cyanosism petechiae, seizures, anxiety, and multiple organ dysfunction syndromes.