Modeling Optimal Laboratory Testing Strategies for Bacterial Meningitis Surveillance in Africa.

Since 2010, the introduction of an effective serogroup A meningococcal conjugate vaccine has led to the near-elimination of invasive Neisseria meningitidis serogroup A disease in Africa's meningitis belt. However, a significant burden of disease and epidemics due to other bacterial meningitis pathogens remain in the region. High-quality surveillance data with laboratory confirmation is important to monitor circulating bacterial meningitis pathogens and design appropriate interventions, but complete testing of all reported cases is often infeasible. Here, we use case-based surveillance data from 5 countries in the meningitis belt to determine how accurately estimates of the distribution of causative pathogens would represent the true distribution under different laboratory testing strategies. Detailed case-based surveillance data was collected by the MenAfriNet surveillance consortium in up to 3 seasons from participating districts in 5 countries. For each unique country-season pair, we simulated the accuracy of laboratory surveillance by repeatedly drawing subsets of tested cases and calculating the margin of error of the estimated proportion of cases caused by each pathogen (the greatest pathogen-specific absolute error in proportions between the subset and the full set of cases). Across the 12 country-season pairs analyzed, the 95% credible intervals around estimates of the proportion of cases caused by each pathogen had median widths of ±0.13, ±0.07, and ±0.05, respectively, when random samples of 25%, 50%, and 75% of cases were selected for testing. The level of geographic stratification in the sampling process did not meaningfully affect accuracy estimates. These findings can inform testing thresholds for laboratory surveillance programs in the meningitis belt.

Pneumococcal Carriage in Burkina Faso After 13-Valent Pneumococcal Conjugate Vaccine Introduction and Before a Schedule Change.

Background: In October 2013, Burkina Faso introduced 13-valent pneumococcal conjugate vaccine (PCV13) into the routine childhood immunization program using 3 primary doses with no booster. Previous pneumococcal carriage studies showed reductions in vaccine-type (VT) carriage in children aged <5 years but not in older age groups. Methods: We conducted a cross-sectional, age-stratified pneumococcal carriage study among healthy persons aged ≥1 month in Bobo-Dioulasso in March 2020. Pneumococci isolated by culture from nasopharyngeal swabs (all participants) and oropharyngeal swabs (participants aged ≥5 years) were serotyped by polymerase chain reaction; a subset was serotyped by Quellung. Using data from a study with the same design from March 2017, we examined changes in pneumococcal carriage by age group. Results: Among 1005 (2017) and 1002 (2020) enrolled participants, VT carriage decreased (21.6% to 15.9%; adjusted prevalence ratio [aPR], 0.76 [95% confidence interval {CI}, .63-.92]). By age group, decline in VT carriage was significant among children aged 5-14 years (28.9% to 16.3%; aPR, 0.57 [95% CI, .39-.84]) but not among children aged <5 years (22.4% to 19.1%; aPR, 0.87 [95% CI, .70-1.09]) or adults aged ≥15 years (12.0% to 5.5%; aPR, 0.52 [95% CI, .26-1.05]). Conclusions: Between 3 and 6 years after PCV13 introduction, significant declines in VT carriage were observed in older children, possibly reflecting indirect effects of PCV13 use. VT carriage in children aged <5 years remained stable with almost 1 in 5 carrying VT pneumococci, suggesting limitations to a PCV schedule without a booster dose.

Field Evaluation of the Performance of Two Rapid Diagnostic Tests for Meningitis in Niger and Burkina Faso.

New lateral flow tests for the diagnosis of Neisseria meningitidis (Nm) (serogroups A, C, W, X, and Y), MeningoSpeed, and Streptococcus pneumoniae (Sp), PneumoSpeed, developed to support rapid outbreak detection in Africa, have shown good performance under laboratory conditions. We conducted an independent evaluation of both tests under field conditions in Burkina Faso and Niger, in 2018-2019. The tests were performed in the cerebrospinal fluid of suspected meningitis cases from health centers in alert districts and compared to reverse transcription polymerase chain reaction tests performed at national reference laboratories (NRLs). Health staff were interviewed about feasibility. A total of 327 cases were tested at the NRLs, with 26% confirmed Nm (NmC 63% and NmX 37%) and 8% Sp. Sensitivity and specificity were, respectively, 95% (95% CI: 89-99) and 90% (95% CI: 86-94) for Nm and 92% (95% CI: 75-99) and 99% (95% CI: 97-100) for Sp. Positive and negative predictive values were, respectively, 77% (95% CI: 68-85) and 98% (95% CI: 95-100) for Nm and 86% (95% CI: 67-96) and 99% (95% CI: 98-100) for Sp. Concordance showed 82% agreement for Nm and 97% for Sp. Interviewed staff evaluated the tests as easy to use and to interpret and were confident in their readings. Results suggest overall good performance of both tests and potential usefulness in meningitis outbreak detection.