Decreases in invasive Haemophilus influenzae diseases in US Army children, 1984 through 1991
L. E. Broadhurst, R. L. Erickson and P. W. Kelley
Department of Advanced Preventive Medicine Studies, Walter Reed Army Institute of Research, Washington, DC 20307-5100.
OBJECTIVE--To document trends in the incidence of invasive Haemophilus
influenzae diseases in young children of US Army active duty soldiers
following the publication of H influenzae type b immunization
recommendations for young children between 1985 and 1990. DESIGN--A
population-based surveillance of hospital discharge diagnoses for H
influenzae invasive diseases. SETTING--Military and civilian medical
treatment facilities around the world. PATIENTS--There was a mean
population of nearly 200,000 US Army health care beneficiaries younger than
5 years of age each year of the study. OUTCOME MEASURES--Annual total and
age-specific incidences of the six most common H influenzae invasive
diseases in this population (meningitis, epiglottitis, septicemia,
pneumonia, cellulitis, and septic arthritis). RESULTS--The annual number of
cases of H influenzae invasive diseases decreased from a high of 188 in
1986 to 43 in 1991. The incidence in the age group at highest risk for H
influenzae disease, those 6 to 11 months of age, decreased from 355 per
100,000 children in 1986 to 116 per 100,000 in 1991 (P < .0001, chi 2
for trend). The incidence for H influenzae meningitis declined from 59 per
100,000 children in 1986 to 6 per 100,000 in 1991 (P < .0001, chi 2 for
trend). CONCLUSIONS--The decrease in H influenzae invasive diseases closely
follows the dates of H influenzae type b vaccine licensure for use in
progressively younger age groups. Some age groups, however, experienced a
decline in disease rates even before becoming eligible for vaccination.
