Invasive Group B Streptococcal Disease in South Africa: Importance of Surveillance Methodology

Vanessa Quan, Jennifer R. Verani, Cheryl Cohen, Anne von Gottberg, Susan Meiring, Clare L. Cutland, Stephanie J. Schrag, Shabir A. Madhi, Jose Melo-Cristino
2016 PLoS ONE  
Data on neonatal group B streptococcal (GBS) invasive disease burden are needed to refine prevention policies. Differences in surveillance methods and investigating for cases can lead to varying disease burden estimates. We compared the findings of laboratorybased passive surveillance for GBS disease across South Africa, and for one of the provinces compared this to a real-time, systematic, clinical surveillance in a population-defined region in Johannesburg, Soweto. Passive surveillance
more » ... ied a total of 799 early-onset disease (EOD, <7 days age) and 818 LOD (late onset disease, 7-89 days age) cases nationwide. The passive surveillance provincial incidence varied for EOD (range 0.00 to 1.23/1000 live births), and was 0.03 to 1.04/1000 live births for LOD. The passive surveillance rates for Soweto, were not significantly different compared to those from the systematic surveillance (EOD 1.23 [95%CI 1.06-1.43] vs. 1.50 [95%CI 1.30-1.71], respectively, rate ratio 0.82 [95%CI 0.67-1.01]; LOD 1.04 [95% CI 0.90-1.23] vs. 1.22 [95%CI 1.05-1.42], rate ratio 0.85 [95% CI 0.68-1.07]) . A review of the few cases missed in the passive system in Soweto, suggested that missing key identifiers, such as date of birth, resulted in their omission during the electronic data extraction process. Our analysis suggests that passive surveillance provides a modestly lower estimate of invasive GBS rates compared to real time sentinel-site systematic surveillance, however, this is unlikely to be the reason for the provincial variability in incidence of invasive GBS disease in South Africa. This, possibly reflects that invasive GBS disease goes undiagnosed due to issues related to access to healthcare, poor laboratory capacity and varying diagnostic procedures or empiric antibiotic treatment of neonates with suspected sepsis in the absence of attempting to making a microbiological diagnosis. An efficacious GBS vaccine for pregnant women, when PLOS ONE |
doi:10.1371/journal.pone.0152524 pmid:27055184 pmcid:PMC4824385 fatcat:ucp7kgaiabgbzo66sjoj7t3acy