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

Abstract

The prevalance of N. meningitidis during endemic conditions was studied in 2 groups of people: in group 1, 64 family members to patients with meningococcal disease and in group 2, 64 family members to patients with meningitis due to Hemophilus influenzae or Streptococcus pneumoniae. In group 1 the carrier rate of meningococci of the same serogroup, sensitivity to sulfonamide 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. The risk was calculated to have been 3000-4000 times higher for the family members during 1 mo. after the diagnosis of an index case 1965-1977 in Sweden. 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.