Epidemiology of Neisseria Meningitidis: Prevalence and Symptoms from the Upper Respiratory Tract in Family Members to Patients with Meningococcal Disease

Abstract

The prevalence of Neisseria meningitidis during endemic conditions was studied in 2 groups of people: (1) 64 family members to patients with meningococcal disease, and (2) 64 family members to patients with meningitis due to Haemophilus influenzae or Streptococcus pneumoniae. In group 1 the carrier rate of meningococci of the same serogroup, sensitivity to sulphonamide, and serotype (group B) as the index strain was 34%. The carrier rate of meningococci group A, B, C and Y was 39% in group 1 and 1.6% in group 2. The 25 times higher carrier rate in group 1 gives some explanation of the increased risk for family members to patients with meningococcal disease. This risk was calculated to have been 3000–4000 times higher for the family members during one month after the diagnosis of an index case 1965–1977 in our county. The hypothesis that meningococci as a rule are introduced into a family by an adult and then spread within the family to a child finds no support in the present study. A statistically highly significant association was found between carriage of pathogenic meningococci and symptoms from the upper respiratory tract.