Vacuna anti-Haemophilus influenzae de tipo b (Hib) en el Calendario Nacional de Argentina: portación nasofaríngea de Hib tras 8 años de su introducción

Nasopharyngeal Colonization (NC) by Haemophilus influenzae: 8 years after the introduction of the Haemophilus influenzae type b vaccination in the Argentine National Schedule Introduction: As a part of the PAHO supported protocol "Evaluation of the impact of Haemophilus influenzae b vaccination programs in four Latinamerican countrys", a study took place in Argentine 8 years after introduction of Hib vaccine. Objective: To evaluate the impact of Hib vaccination measuring Nasopharyngeal Colonization (NC) rate and to identify factors associated to Haemophilus influenzae (HI) carrier status. Methods: Cross-sectional study -from June 27th 2005 to April 12th 2006in two pediatric hospitals, HNRG and PE. Nasopharyngeal swab specimens were processed in the INEI-ANLIS "Dr. C. Malbran"; samples were cultured in chocolate agar medium containing bacitracin. Hi was identified with technics of Gram, oxidase, catalase, growth factors (V-X-XV) and test of porphyrin. Capsular serotypification was made by agglutination in lamina with specific antisera and the confirmation by polymerase chain reaction. Population: 900 children of 1 year of age, vaccinated with 3 doses and 700 children of 5 years, with 4 vaccine doses. Results: Hi was detected in 40% (641/1.600) of samples, among Hi, 4,8% (31/641) were encapsulated (3 serotypes a, 1 b, 3 c, 5 d, 7 e, and 12 f). Only one child of 1 year was NC carrier of Hi type b (0.06%).Conclusions: We found a very low NC Hib (0.06%) rate, for this reason associations could not be analyzed. The age, household and day care center contacts were associated with NC by Haemophilus influenzae. (