Haemophilus influenzae infections.

Of the six typeable strains of this organism, type b is the most virulent, accounting for 95% of serious infections in children. Unexpectedly, in adults, nearly two thirds of isolates from blood and CSF were found to be nontypeable. The spectrum of clinical disease associated with type b and nontypeable strains is discussed. Effective immunization of infants is now in the planning stages.