Hemophilus Influenzae Infection in Adults

The immunity of adults to certain common infections of childhood can usually be related to the acquisition of specific antibody through contact with micro-organisms. Immunity to infection by Hemophilus influenzae, Type B, is an excellent example of the solid and durable resistance acquired against a childhood infection and maintained by repeated exposure to the bacillus. The low rate of adult infection is illustrated by the fact that in 467 cases of H. influenzae meningitis only 15 were in patients over the age of 20.1-5An extensive review of the literature has disclosed among adults only 33 cases of meningitis5-10and scattered reports of endocarditis, brain abscess, obstructive laryngitis, pyarthrosis,11and pneumonia12due to H. influenzae, Type B. While the resistance of most adults to infection by H. influenzae is readily understood on the basis of acquired immunity, little effort has been made to explain the lack