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. 2012;7(12):e52464.
doi: 10.1371/journal.pone.0052464. Epub 2012 Dec 20.

Pneumococci in the African meningitis belt: meningitis incidence and carriage prevalence in children and adults

Judith E Mueller  1 , Seydou Yaro, Macaire S Ouédraogo, Natalia Levina, Berthe-Marie Njanpop-Lafourcade, Haoua Tall, Régina S Idohou, Oumarou Sanou, Sita S Kroman, Aly Drabo, Boubacar Nacro, Athanase Millogo, Mark van der Linden, Bradford D Gessner
Affiliations

Pneumococci in the African meningitis belt: meningitis incidence and carriage prevalence in children and adults

Judith E Mueller et al. PLoS One. 2012.

Abstract

Background: The development of optimal vaccination strategies for pneumococcal conjugate vaccines requires serotype-specific data on disease incidence and carriage prevalence. This information is lacking for the African meningitis belt.

Methods: We conducted hospital-based surveillance of acute bacterial meningitis in an urban and rural population of Burkina Faso during 2007-09. Cerebrospinal fluid was evaluated by polymerase chain reaction for species and serotype. In 2008, nasopharyngeal swabs were obtained from a representative population sample (1 month to 39 years; N = 519) and additional oropharyngeal swabs from 145 participants. Swabs were evaluated by culture.

Results: Annual pneumococcal meningitis incidence rates were highest among <6-month-old (58/100,000) and 15- to 19-year-old persons (15/100,000). Annual serotype 1 incidence was around 5/100,000 in all age groups. Pneumococcal carriage prevalence in nasopharyngeal swabs was 63% among <5-year-old children and 22% among ≥5-year-old persons, but adding oropharyngeal to nasopharyngeal swabs increased the estimated carriage prevalence by 60%. Serotype 1 showed high propensity for invasive disease, particularly among persons aged ≥5 years.

Conclusions: Serotype 1 causes the majority of cases with a relatively constant age-specific incidence. Pneumococcal carriage is common in all age groups including adults. Vaccination programs in this region may need to include older target age groups for optimal impact on disease burden.

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Conflict of interest statement

Competing Interests: JEM, HT, BMNL, RSI, and BDG work for AMP which receives unrestricted support from Sanofi Pasteur and grant specific support from Sanofi Pasteur, GSK, Merck, Pfizer, and Crucell. MVDL received research grants and honoraria from Pfizer, GSK, Sanofi Pasteur, and MSD. No other conflicts exist. For members of AMP, this relation was (and is) indirect via unrestricted funding from Sanofi Pasteur to AMP and specific project funding; no AMP authors have individual conflicts of interest (employment, consultancy, patents, products in development or marketed products etc). MVDL received consultancy and project funding, but not employment, patents, products in development or marketed products. At no time was the funder involved in analyses, interpretation of the results or manuscript writing. Altogether, these relations do not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. Monthly incidence rates of bacterial meningitis in Bobo-Dioulasso, Burkina Faso, March 2007 to December 2009.
a) Pneumococcal (black line) and meningococcal (grey line) meningitis. b) Age-specific rates of pneumococcal meningitis, by season. Black lines, dry season. Grey lines, rainy season. Full lines, all pneumococcal cases. Dashed lines, serotype 1 cases only. Asterixes, 95% confidence intervals of incidence rates of all pneumococcal cases do not overlap between dry vs. rainy season, suggesting statistical significance of difference.
Figure 2
Figure 2. Serotype or -group distribution among carriage (dark gray) and pneumococcal cases (light gray), Burkina Faso, 2007–9.
Serotyping based on cerebrospinal fluid polymerase chain reaction testing or Quellung reaction on invasive isolates; and on Quellung reaction for carriage isolates. Each panel A–C shows only serotypes that were found in this age category. A: children <1 years of age, 92 nasopharyngeal carriage and 32 cases. B: children 1–4 years of age, 98 carriage isolates (90 nasopharyngeal, 8 oropharyngeal) and 10 cases. C: children ≥5 years of age and adults, 203 carriage isolates (157 nasopharyngeal, 46 oropharyngeal) and 84 cases. NT, invasive isolates with serotypes not included in the PCR serotyping algorithm (29 primers); or carriage isolates yielding negative results in the Quellung reaction panel.
Figure 3
Figure 3. Age-specific pneumococcal carriage prevalence by carriage site in pharynx among 145 participants with both naso- and oropharyngeal swabs.
Bobo-Dioulasso, 2008.
See this image and copyright information in PMC

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