Nasopharyngeal carriage of meningococcus and meningococcal meningitis in Sokoto, Nigeria.

In an attempt to determine the epidemiology of meningococcal diseases in Sokoto, Nigeria, nasopharyngeal carriage of meningococcus was studied among the groups at the greatest risk of the disease, i.e. children and young adults. Of 726 subjects sampled, 45 (6.2%) carried meningococcus. Sixteen (35.6%) of the 45 isolates belonged to serogroup B. Others were as follows: group A, 8 (17.8%), C, 5 (11.1%), D, 1 (2.2%) and non-groupable 11 (24.4%). Clinical cases encountered during the period were caused by serogroups A (5, 62.5%) and C (3, 37.5%). A male:female carriage ratio of 1.2:1 was recorded for the potential epidemic serogroups, A and C (chi2 = 1.0091; p>0.05), while the clinical case ratio for the genders was 1.8:1 (chi = 16.1619; p<0.001). The 5-9-y-old age group carried meningococci more frequently (8.5%) than other age brackets, and also registered the highest incidence (46.5%) of the cases. Closeness of contact with a clinical case increased the carriage of the strain of the case (chi2 = 33.3940; p<0.001). Rural dwellers carried meningococcus more frequently than urban dwellers (chi2 = 9.5591; p<0.05). The season had no consistent influence on carriage rates, even though it significantly influenced the outbreaks of the disease. Mass vaccination with polysaccharide vaccine and improved living conditions appear to be the most practical ways to control meningococcal diseases in Africa.