With time, immunity to serogroups in the community is acquired. Therefore, the highest infection rates are in young children. Viral upper respiratory infections may create an opportunity for meningococcal disease. Crowded living conditions, such as military barracks, are associated with increased carriage rates and epidemic infections. During epidemic outbreaks the disease rate can increase 100 fold.
Attack rates are highest in winter and early spring.
It occurs often during or after an upper respiratory infection. Onset is characterized by malaise, myalgias, arthralgias, fever, chills and sometimes diarrhea. These symptoms may resolve over one to three days or may lead to erythematous macular lesions over the extremities, often with purpura. There can be tachypnea, tachycardia, or mild hypotension and the syndrome can progress to meningitis with confusion, headache, and nuchal rigidity. Blood cultures are usually positive and the syndrome responds promptly to high-dose penicillin.