Dg. Perdue et al., Invasive Haemophilus influenzae disease in Alaskan residents aged 10 yearsand older before and after infant vaccination programs, J AM MED A, 283(23), 2000, pp. 3089-3094
Citations number
30
Categorie Soggetti
General & Internal Medicine","Medical Research General Topics
Context The introduction of Haemophilus influenzae type b (Hib) vaccination
of children has led to a decline in incidence of Hib disease in young Alas
kan children, How ever, the impact of vaccination on unimmunized Alaskan ad
olescents and adults has not been studied.
Objective To characterize trends in incidence of and mortality due to invas
ive H influenzae disease in Alaskan residents aged 10 years and older prior
to and after the introduction of a statewide Hib infant vaccination progra
m.
Design and Setting Population-based, descriptive correlational study conduc
ted 1980-1996 in Alaska,
Subjects One hundred twenty-nine individuals (31 Alaska Natives and 98 nonn
ative Alaska residents) aged 10 years and older in whom H influenzae was cu
ltured from a normally sterile site.
Main Outcome Measures Incidence of H influenzae infection before (1980-1990
) vs after (1991-1996) vaccination program initiation; serotype, biotype, a
nd p-lactamase production of isolates.
Results The overall annual incidence of invasive H influenzae in those aged
10 years and older declined 33%, from 2.1 per 100000 persons per year to 1
.4 per 100000 persons per year (P=.03) after initiation of statewide infant
Hib vaccination programs in 1991. This reduction appeared to be the result
of a decrease in serotype b disease (82%; P<.001). Infection with other H
influenzae serotypes and nontypeable strains increased from 0.5 per 100000
persons per year to 1.1 per 100000 persons per year (P =.01). Incidence dec
lined from 4.2 per 100000 persons per year to 1.2 per 100000 persons per ye
ar in Alaska Natives (P=.005) and from 1.7 per 100000 persons per year to 1
.4 per 100000 persons per year in non native Alaska residents (P =.37). Pne
umonia (43%), sepsis (26%), and meningitis (16%) were the most common clini
cal presentations. Alcohol/drug abuse was comorbid in 15% of patients, whil
e 13% of patients were pregnant women. beta-Lactamase production occurred i
n 35% of isolates and was stable throughout the surveillance. The overall c
ase-fatality rate was 15%.
Conclusion The overall statewide incidence of invasive H influenzae infecti
ons in unimmunized persons aged 10 years and older decreased after the init
iation of an infant Hib vaccine program, perhaps by decreasing Hib carriage
in child reservoirs. An increase in non-serotype b strains was observed. T
his trend justifies the need for continued surveillance of invasive disease
caused by H influenzas.