Intrafamily spread of Haemophilus type b infections.

Meningitis and epiglottitis are the clinical manifestations of severe Haemophilus influenzae serotype b infection. Compared with meningitis, epiglottitis occurs in older children. When secondary cases occur within the family, the type of clinical manifestation produced by this serotype is generally similar in siblings. This report concerns the unusual occurrence of meningitis developing in older child and epiglottitis developing in the younger one. We discuss the possible explanations for this unusual pattern. We also survey the spread of H influenzae both within and outside the family unit and review the present status of histocompatibility antigens and Haemophilus disease.