Haemophilus influenzae Type b Conjugate Vaccines

Publisher Website
Google Scholar
Abstract
Haemophilus influenzae, a gram-negative rod-shaped bacterium, is a major human pathogen that causes a range of diseases in infants, children, and adults. There are six antigenic types of H. influenzae, termed a-f, whose antigenic specificity is provided by the capsular Polysaccharide (Ps). There also are nontypeable strains which lack a capsular Ps. H. influenzae type b (Hib) is the most pathogenic H. influenzae strain for infants and young children and a major cause of invasive bacterial infections. Until the 1990s, Hib caused an estimated 10,000 cases of meningitis per year in children 2 months to 5 years of age in the United States (Vadheim and Ward, 1994). The mortality rate is up to 5% in developed countries, and up to 35% of survivors may develop permanent neurological sequelae. Other invasive Hib infections include cellulitis, empyema, endocarditis, endophthalmitis, epididymitis, epiglottitis, osteomyelitis, pericarditis, pneumonia, septic arthritis, and tracheitis (Kaplan, 1994). While the total incidence of such Hib infections was approximately equal to that of Hib meningitis in the United States, these diseases vary significantly in relative incidence elsewhere in the world. As a result of the development and widespread use of Hib conjugate vaccines in several developed countries, the incidence of invasive Hib diseases has decreased by about 95% in the United States (M.M.W.R., 1994) and 60–80% in other countries (Vadheim and Ward, 1994).