Bacterial Meningitis and Haemophilus influenzae Type b Conjugate Vaccine, Malawi

Acute bacterial meningitis (ABM) is a major cause of illness and death in children in sub-Saharan Africa. Neisseria meningitidis is the most common cause of ABM in the meningitis belt (sub-Saharan Africa), and Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) are the most common causes in southern and eastern Africa. Of 114 case-patients with meningitis and positive cerebrospinal fluid (CSF) cultures who came to the Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi (southeastern Africa), during 1996–1997, more than half of these cases were caused by S. pneumoniae, Hib, or Salmonella spp. In February 2002, Malawi introduced Hib conjugate vaccine in a pentavalent formulation that includes vaccine against diphtheria, pertussis, tetanus, and hepatitis B. There was no mass campaign or catch-up program. This vaccine is given routinely to patients at 6, 10, and 14 weeks of age; vaccination coverage has been ≈90% since 2002. Incidence of Hib meningitis decreased but the long-term effect of the vaccination program remains unclear (6). We examined the effectiveness of Hib conjugate vaccine by conducting a retrospective database review of children with ABM who came to QECH in Blantyre, Malawi during 1997–2009.