The Elimination of Haemophilus influenzae type b meningitis following conjugate vaccine introduction in Senegal.

BACKGROUND: Senegal introduced routine infant Haemophilus influenzae type b (Hib) conjugate vaccine during 2005. METHODS: We evaluated acute bacterial meningitis surveillance data among children 0 to 59 months of age collected during January 2003 to September 2007 at the major pediatric referral hospital in the Dakar Region of Senegal. Hib vaccine effectiveness was assessed using a case-control design. RESULTS: A total of 1749 children with suspected bacterial meningitis were included in the current study of whom 142 (8%) had Hib identified. Among children less than age 1 year, the average annual Hib meningitis incidence decreased from 22 to 47 per 100,000 during 2003-2005 to 1.4 per 100,000 during 2007, while pneumococcal meningitis incidence remained stable. Before vaccine introduction, calculated incidences varied over 4-fold between districts within the Dakar Region for the years 2003 to 2005. Following use of Hib vaccine, pneumococcus has now become the most common etiology of pediatric acute bacterial meningitis in Dakar region. CONCLUSIONS: Senegal successfully implemented Hib conjugate vaccine into their routine infant immunization program with a resultant near elimination of Hib meningitis burden.

Haemophilus influenzae type b conjugate vaccine impact against purulent meningitis in Rwanda.

Rwanda introduced Haemophilus influenzae type b (Hib) conjugate vaccine in January 2002 and simultaneously implemented pediatric bacterial meningitis surveillance at a major referral hospital in the capital Kigali. We reviewed clinical and laboratory information collected during January 2002 to June 2006. Due to a variety of laboratory limitations, only eight confirmed Hib cases were identified, all before 2004. However, the proportion of cerebrospinal fluid with purulence decreased from 26.0% during 2002, to 15.9% during 2003, 9.7% during 2004 and 8.4% in 2005 (p<0.001). Vaccine effectiveness of two or three doses of Hib vaccine against purulent meningitis was 52% (95% confidence interval, 5-75%). In an African setting with few resources and in which few confirmed Hib meningitis cases were identified, Hib vaccine impact nevertheless could be demonstrated against the outcome of purulent meningitis and was found to be high.

The impact of routine infant immunization with Haemophilus influenzae type b conjugate vaccine in Malawi, a country with high human immunodeficiency virus prevalence.

Malawi has extreme poverty and a high-human immunodeficiency virus (HIV) prevalence. Following Haemophilus influenzae type b (Hib) conjugate vaccine introduction during 2002, we evaluated vaccine impact by reviewing hospital surveillance data for acute bacterial meningitis in Blantyre district among children age 1-59 months admitted during 1997-2005. Documented annual Hib meningitis incidence rates decreased from 20-40/100,000 to near zero among both rural and urban residents despite no change in pneumococcal meningitis incidence rates. Before vaccine introduction, an average of 10 children/year had Hib meningitis and HIV infection compared to 2/year during 2003-2004 and none during 2005. Vaccine effectiveness was high following two or more doses of vaccine. The most urgent future need is for a sustainable routine infant immunization program, including a less expensive vaccine that preferably is delivered in a multivalent form.