[The association between deficiency of terminal complement components and the occurrence of meningococcal meningitis].

Seventeen patients with sporadic meningococcal meningitis, registered in Fukuoka city, were studied for complement deficiency. Four of the seventeen had a selective deficiency of the ninth component of the complement (C9), four had a deficiency of the seventh component of the complement (C7), and one had a deficiency of the fifth component of the complement (C5) as determined by both hemolytic and antigenic assay. Family studies suggested that these complement deficiencies in the present study were hereditary. Based on the incidence (0.036% of homozygous C9 deficiency in Fukuoka (171 C9 deficient individuals of 475, 886 blood donors), we have concluded that patients with C9 deficiency are more susceptible to meningococcal meningitis than normal individuals (p less than 0.001). In addition, the present study further supports that complement deficiency is common in patients with sporadic meningococcal meningitis.