Epidemiology of Invasive Haemophilus influenzae Type A Disease among Navajo and White Mountain Apache Children, 1988-2003

Abstract

Background. Before the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, rates of H. influenzae disease among Navajo and White Mountain Apache (WMA) children were among the highest reported worldwide. Routine Hib vaccination has significantly reduced rates of Hib disease in these populations. As Hib disease rates decrease to very low levels, there are concerns that non-type b strains of H. influenzae may emerge as more prevalent causes of invasive disease in children. Methods. We reviewed population-based, active laboratory surveillance data from the period of 1988–2003 for invasive H. influenzae type a (Hia) disease among Navajo and WMA children aged Results. During 1988–2003, a total of 76 reported cases of invasive Hia disease occurred among Navajo and WMA children. The overall annual incidence was 20.2 cases per 100,000 population aged Conclusions. Active surveillance data showed high rates of invasive Hia disease among Navajo and WMA children but no increase in the incidence after Hib vaccination was introduced. The presentation of Hia disease is similar to that of Hib disease in the prevaccine era.