Y-023. Haemophilus influenzae Carriage in Healthy Children and Adults in Vietnam

N. D. Phillips, C. A. Talarico, C. F. Marrs, J. R. Gilsdorf;
Univ. of Michigan, Ann Arbor, MI.

The introduction of the Haemophilus influenzae type b (Hib) vaccine has dramatically reduced carriage and disease associated with Hib. However, disease associated with other serotypes and nontypable strains persist in spite of vaccination. The aim of this study was to describe H. influenzae nasopharyngeal colonization in healthy children and adults prior to Hib vaccine introduction into Vietnam. We conducted a cross-sectional study of nasopharyngeal (NP) carriage in Nha Trang, Vietnam, in October 2006. One NP swab specimen was collected from each member of 115 households and stored in skim milk-tryptone-glucose-glycerin (STGG) media. Specimens were shipped to the University of Michigan for culture using standard techniques. H. influenzae were distinguished from nonhemolytic H. haemolyticus by presence of iga and lgtC by dot blot hybridization. 78 households contained at least one child < 5 years, and 37 households contained only adults. Preliminary results show 29% of children < 5 years were colonized with H. influenzae. 9% of children 6-17 years and 2% of adults in household contact with children were colonized. 1% of adults not in household contact with children were colonized. 26 households had more than two children < 5 years; of these households, 15% had at least two children colonized. Haemophilus influenzae carriage is common among young children in Vietnam. Interestingly, adult carriage does not seem dependent on household contact with children, and sharing amongst young children appears uncommon. Molecular typing techniques are currently being utilized to further characterize the diversity of asymptomatic colonization with H. influenzae. Hib vaccine is warranted in this high transmission environment; however, surveillance should continue for carriage and disease caused by all serotypes including nontypable strains.