Haemophilus influenzae colonization and its risk factors in children aged <2 years in northern India.

The disease burden and the age group of children most affected by Haemophilus influenzae remain controversial particularly in many countries of South Asia. Nasopharyngeal carriage of H. influenzae can indicate the transmission dynamics in these settings. In a prospective population-based study, nasopharyngeal swabs from 1000 children aged <2 years, belonging to various socioeconomic groups from rural and urban areas of northern India were taken. The prevalence of H. influenzae carriage was found to be 11.2%. Among these isolates, 69% belonged to type b and the rest were non-typable. The age group most affected was 18-21 months. The carriage rate was influenced by age and socioeconomic factors namely type of housing, overcrowding, and season. Hib carriage is quite common in northern India and it is associated with age, type of housing, overcrowding, and season. Since carriage gets established early, Hib vaccination should target children in early infancy.