PCR-based surveillance in five districts in Burkina Faso and Togo during the 2003–04 epidemic season

Abstract number: 1134_04_6

Aguilera J.F., Lourd M., Yaro S., Adjogble K., Traoré Y., Lafourcade B., Ouédraogo M., Leblond A., Gessner B.

Objectives:  

To determine in selected districts of Burkina Faso (BF) and Togo during the 2003–04 meningitis epidemic season epidemiological characteristics of acute bacterial meningitis (ABM) and the sensitivity and specificity of cerebrospinal fluid (CSF) testing using polymerase chain reaction (PCR) versus culture.

Methods:  

We conducted a prospective health centre and hospital-based surveillance study. We collected CSF specimens and clinical/demographical information from suspected cases of ABM detected within all health facilities in three districts of BF and two district referral hospitals in Togo. A confirmed case was defined as detection of bacteria in CSF using latex agglutination, culture or PCR. Routine microbiological techniques were strengthened (only in BF) and we established for both countries appropriate specimen transport systems to National Reference Laboratories in BF for PCR testing or culture.

Results:  

A total of 329 clinical cases of ABM were included from BF and 207 from Togo. Among 117 (36%) confirmed cases from BF, we identified 53 (45%) Streptococcus pneumoniae (Sp), 49 (42%) Neisseria meningitidis (Nm) and 15 (13%) Haemophilus influenzae (Hi). Among 143 confirmed cases from Togo, we identified 66 (46%) Nm, 52 (36%) Sp and 25 (17%) Hi. In BF and Togo, Nm A represented 55% and 83%, and Nm W135 31% et 8% of Nm cases, respectively. In BF, most isolated Sp were serotype 1 (8/22) or 6 (5/22) (preliminary results, genotyping under process). The case fatality ratio in BF was 54%, including 44% for Sp, 6% for Nm and 27% for Hi. In BF, PCR sensitivity and specificity varied from 94–96% and 97–100%, respectively, depending on the etiology. In Togo, PCR allowed confirmation of an additional 65% of cases compared to culture or latex agglutination.

Conclusion:  

Most ABM cases in selected areas of BF and Togo were due to Sp or Nm A; the proportion of W135 varied depending on the country and was lower in BF when compared to the previous epidemic season. The continued confirmed circulation of Sp serotype 1 emphasizes the need to include this serotype in any vaccine formulation designed for use in Sub-Saharan Africa. PCR performs well relative to culture and allows identification of substantially more cases than culture or latex agglutination. We recommend expanding similar surveillance to other areas of the African meningitis belt.