Background: Within a few months we twice observed the following situation: In each of two different communities, a young child fell ill with meningitis caused by Haemophilus influenzae type B (HIB). One week later, a second case occurred in the same community. Both patients had had no direct contact with each other. But each had an asymptomatic older sibling. These siblings attended the same kindergarten and had close contact with each other. The isolated HIB strains were identical (capsular type b, biotype I, outer membrane protein subtype 1 and lipopolysaccharide serotype 1) and were beta-lactamase-negative.
Conclusion: Since it must be assumed that the causative HIB strains circulated in the respective kindergartens and were transmitted to the patients by their healthy siblings, a rifampicin chemoprophylaxis was instituted which included all kindergarten children and their younger siblings. Since the current guidelines on chemoprophylaxis in HIB meningitis do not deal with a situation like the one encountered by us, a revision of the present guidelines was proposed and has been implemented in the meantime.