RESUMO
OBJECTIVE: To determine the prevalence of H. influenzae (Hi) carrier state among children, in Ciudad Nezahualcóyotl, State of Mexico. MATERIAL AND METHODS: A cross-sectional comparative random study was designed. Study subjects were 639 children under 15 years of age, stratified by age and sex. Nasopharyngeal cultures were used to identify Hi and to typify encapsulated strains. Sample size was computed with the software package Epi-Info, using a p value of 0.5%, 95% confidence intervals and a 5% error; statistical analysis was performed using frequencies, means and proportions. Differences were tested by comparison of two proportions from independent populations. RESULTS: Hi was isolated from 136 of 639 pharyngeal cultures (21%). Hi types found were Hi b (n = 6, 4%), Hi a, c, and f (n = 5, 4%), and non-typifiable (NT) Hi (n = 125, 92%). CONCLUSIONS: The prevalence of pharyngeal colonization by Hi found among children under 15 years of age, in Ciudad Nezahualcóyotl, is similar to that reported in the literature. The inverse relation of pharyngeal carriers with age can be accounted for by the progressive development of specific and non-specific immunity against encapsulated and non-encapsulated strains.
