Knowing what we're up against: high prevalence of Group B strep behind sepsis in mothers and infants

In sub-Saharan Africa, neonatal infection - particularly sepsis, pneumonia, and meningitis - is the single most common cause of death for newborns. Each year, there are about 325,000 of these deaths due to sepsis or pneumonia alone, contributing to nearly 30% of the 1.16 million newborn deaths in Africa. Group B Streptococcus (GBS) has been established as the leading cause of neonatal sepsis and meningitis in high-income countries, but studies are not nearly as conclusive in low- and middle-income countries. However, studies have shown that GBS potentially plays an important role as a neonatal pathogen in sub-Saharan Africa. Research in countries of varying income levels found that 10-40% of women carry GBS during pregnancy, with country-specific studies finding carriage rates to be 28% in South Africa, 21% in Malawi, and 23% in Tanzania, and 22% in Gambia.

Especially worrisome is that there are many factors that favor "vertical transmission" (mom to baby) of the GBS from mother to baby, such as density and severity of the bacteria colony. While maternal HIV infection has not been decisively linked to the presence of GBS during pregnancy, a study in Malawi did find a direct relationship between maternal CD4 cell counts and the presence of GBS.

Intrapartum antibiotic prophylaxis (IAP), have been shown to be successful in reducing early-onset GBS-related diseases by 80%, but remain ineffective against late-onset diseases. IAP works to reduce vertical transmission by decreasing the number of GBS bacteria during delivery and to ensure an effective level of antibiotic in the baby’s circulation. Unfortunately, most of the studies done on IAP have been focused on high-income countries, resulting in data that may not be reasonably be used for countries in sub-Saharan Africa where the disease burden is especially high.

A study by Quan et al. (2016) on GBS and the importance of surveillance methodology found that much more data on GBS invasive disease burden is needed in order to make the most effective prevention policies. A review of lab-based passive surveillance and real-time, systematic, clinical surveillance in Johannesburg, Soweto suggest that passive surveillance resulted in a somewhat lower estimate of invasive GBS. Passive systems are, of course, still important tools when interpreted correctly, but active systems are more detailed and representative overall.

Ultimately, many challenges still remain in reducing GBS, particularly in resource-poor regions of the world. Clinicians need to be properly trained to recognize early signs of the disease and treat them quickly and appropriately.  We at Maternova are on the lookout for ultra low cost Strep B detection kits for the bedside.   Preventative measures and evidence to support the development of these measures is also critical. Lastly, effective surveillance systems need to be in place to monitor uptake, implementation, and impact of these policies on neonatal mortality.

Blog by Vivian Shih