Systemic meningococcal infections in patients with acquired complement deficiency.

Congenital deficiency of the late components of the complement may predispose the individual to systemic meningococcal infection. Assuming that patients with acquired complement deficiencies may also have an increased risk of contracting meningococcal infections, a retrospective and prospective study to assess this association was conducted. Over 20 years (1970-1989), 30 patients with meningococcemia or meningococcal meningitis, proven by blood or CSF culture, were treated at the Beilinson Medical Center. Only one patient died of the infection. Risk factors were found in three patients (10%). One had a congenital deficiency of C7, and two had acquired complement deficiency due to systemic lupus erythematosus (SLE) and membranoproliferative glomerulonephritis (MPGN). These latter two patients had low serum concentration of C3 and C4 and reduced complement hemolytic activity before onset of the infection. Since the incidence of culture-proven systemic meningococcal infection in the Jewish population in central Israel is 1/100,000, and the prevalence of SLE and MPGN is, at most, 250/100,000, the finding of two patients with meningococcal infection and these rare disorders is over 100 times the expected incidence. We conclude that patients with acquired complement deficiency are at significant risk of meningococcal infection.