b型流感嗜血杆菌—英文课件.ppt

Haemophilus influenzae type b  Using vaccines to measure disease burden: A Tale of Two Studies Presentation to PABIO 550 Diseases of Public Health Importance and Their Control David Mercer, Ph.D. Hib - characteristics Gram negative cocco-bacilli carried by 3% to 15% of young children in the world causes disease in young children meningitis pneumonia epiglottitis septic arthritis Hib disease Industrialized countries median age 1-2 years most meningitis then epiglottitis? meningitis mortality under 5% affects 1-2/1000 children Developing countries (Africa) median age 6-9 months most pneumonia, then meningitis meningitis mortality 20-50% affects 10/1000 children? Gambian PRP-T trial 42,000 infants randomized to receive PRP-T or placebo at 2, 3 and 4 months of age population studied for: Hib meningitis Hib pneumonia all pneumonia Hib carriage Study design individually randomized, double blind study major effort to detect Hib pneumonia randomization in 10 groups numbered 0 through 9: Final results, March 199642,848 infants enrolled PRP-T group 21,490 infants 1272 possible Hib disease 616 chest radiographs 173 lumbar punctures 71 lung aspirates Control group 21,358 infants 1342 possible Hib disease 653 chest radiographs 192 lumbar punctures 75 lung aspirates Did the vaccine actually prevent pneumonia? What did the Gambia trial tell us about the epidemiology of Hib pneumonia in West Africa? Hib is responsible for about 20% of radiological pneumonia in Gambian infants Previous studies had suggested 5-10% of pneumonia due to Hib Very little “WHO pneumonia” which is not radiologically obvious is due to Hib Conclusions PRP-T effectively prevented meningitis and pneumonia due to Hib in The Gambia Hib vaccines have been proven in Finland, USA, UK, Chile and other countries… Why aren’t Hib vaccines used everywhere? Why are Hib vaccines not used all over the world? cost varies, currently $2 per dose affordable for most Asian countries understanding of burde