infectious diseases
Meningococcal Diseases
Introduction
Meningococci (Neisseria meningitidis) are gram-negative diplococci that cause meningitis and meningococcemia. Symptoms, usually severe, include headache, nausea, vomiting, photophobia, lethargy, rash, multiple organ failure, shock, and disseminated intravascular coagulation. Diagnosis is clinical, confirmed by culture. Treatment is penicillin or a third-generation cephalosporin. Meningococci are gram-negative aerobic diplococci that belong to the family Neisseriaceae. There are 13 serogroups; 6 serogroups (A, B, C, W135, X, and Y) cause most human disease. Worldwide, the incidence of endemic meningococcal disease is 0.5 to 5/100,000, with an increased number of cases during winter and spring in temperate climates. Local outbreaks occur most frequently in sub-Saharan Africa between Gambia and Senegal in the west and Ethiopia, Eritrea, and northern Kenya in the east; this area is known as the sub-Saharan (African) meningitis belt, which includes 26 countries. In major African epidemics (which were often caused by serogroup A), attack rates ranged from 100 to 800/100,000 and affected up to 200,000 people each year. After widespread use of the meningococcal A vaccine in the African meningitis belt, serogroup A has been replaced by other meningococcal serogroups and byStreptococcus pneumoniae. ). Outbreaks tend to occur in semiclosed communities (eg, military recruit camps, college dormitories, schools, day care centers) and most often involve patients 16 to 23 years of age. Serogroups B and C cause 50 to 80% of invasive disease ( Reference ). Serogroup A is rare in the US. 