July is International Group B Strep Month. This blog post gives an overview of the illness and its impact on pregnant women around the globe.
Group B Streptococcus bacteria (GBS), also known as Streptococcus agalactiae, typically colonize the gastrointestinal and genitourinary tracts, the throat, and the skin. GBS disease is caused when bacteria enter a normally sterile site such as the blood, bone, or spinal fluid. Both children and adults can develop GBS disease. The disease usually develops in infants that are 0-90 days old and adults that are 60 years of age and older with underlying chronic illnesses. There is currently no vaccine for GBS disease.
Although GBS may come from unknown sources, one out of four pregnant women are carrying the bacteria in their vagina or rectum and can vertically transmit an infection to their newborns. Infections occur during labor (“early-onset disease” or EOD) or within the first week of life through three months of age (“late-onset disease” or LOD). Symptoms can be difficult to distinguish from other infections and range from fever, difficulty breathing, lethargy, and “blue” skin. Severe symptoms that can develop in newborns and infants include sepsis and pneumonia. Meningitis is more likely to occur in infants or newborns with LOD. Complications from GBS disease may result in preterm delivery and lead to developmental disabilities or death. According to the Centers for Disease Control and Prevention (CDC), risk factors for pregnant women include:
- Testing positive for group B strep bacteria late in the current pregnancy (35-37 weeks pregnant)
- Detecting group B strep bacteria in urine (pee) during the current pregnancy
- Delivering early (before 37 weeks of pregnancy)
- Developing a fever during labor
- Having a long time between water breaking and delivering (18 hours or more)
- Having a previous baby who developed early-onset disease
Since 1970, GBS disease has been a topic of concern in health care, research, and public health circles. In 1989, the death of three newborns from GBS disease led to the development of public awareness campaigns that called for improved education, detection, and preventive resources in the U.S. Furthermore, around this time, data collected by the CDC revealed that GBS disease was the leading cause of death in newborns. Parents and advocacy groups actively demanded guidance that would allow for routine screening and the development of an effective vaccine for pregnant moms, globally. Below is a timeline of how advocacy efforts led to research, policy change, and the implementation of effective interventions:
Brief Timeline of GBS Disease Awareness, Education, and Prevention Efforts
- 1990 Group B Strep Association US/International is created. Its primary goals are to:
- Educate the public about GBS infections.
- Promote prevention of neonatal GBS infections through routine prenatal screening.
- Promote the development of a GBS vaccine.
- 1991 GBS researchers awarded a 5-year grant to begin research on a vaccine for GBD disease
- 1992 American College of Obstetrics and Gynecology and American Academy of Pediatrics publish position papers for members
- 1996 CDC Call for Content on GBS Prevention Protocol in (January MMWR)
- 1996 CDC, ACOG, AAP published first consensus statement on GBS National Prevention Guideline in June
- 1997 Group B Strep Association launches its first website
- 2002 The National Consensus Guidelines recommending routine screening for all pregnant woman was published
- 2008 The CDC Active Bacterial Surveillance Core published data that showed an 80% drop in GBS neonatal morbidity and mortality
- 2014 WHO convened the first meeting of the Product Development for Vaccines Advisory Committee (PDVAC); GBS and RSV identified as pathogens that cause a large burden of disease
Globally, it is estimated that EOD makes up 60-90% of GBS disease cases. The mean incidence of GBS disease in infants 0-89 days old is estimated to be .53 cases of GBS infection/1000 live births. The highest incidence of cases is reported to be in the continent of Africa, however, additional studies need to be conducted in low-income countries to better assess the true burden of disease. Prevention methods worldwide include providing prophylactic treatment (antibiotics) to women that are either high-risk or have tested positive for GBS, during labor. With treatment, there is only a 1/4000 chance of the baby becoming infected compared to a 1/200 chance if no treatment is given. In order to identify those who qualify for treatment, a culture-based method can be used to screen all pregnant women between 35-37 weeks for vaginal or rectal colonization of GBS. On the other hand, a risk-based method identifies pregnant women with risk factors for EOD such as fever, preterm delivery, and being in labor for 18 or more hours.
Although the administration of antibiotics during labor reduced EOD from .75 cases of GBS infection/100 live births to .23 cases of GBS infection/100 live births, GBS disease morbidity in infants and mothers is still significant and likely underreported. Antibiotic treatment and GBS disease education are more accessible to pregnant women in high-income countries than those in low-middle income countries. It is likely that challenges related to access to care and health system deficiencies limit the use of antibiotic treatment in low-middle income countries. As a result, the development of a cost-effective vaccine may be able to help bridge an awareness gap.
According to the World Health Organization (WHO), developing a vaccine for maternal immunization is a priority when it comes to GBS disease. In 2016, the WHO Product Development for Vaccines Advisory Committee held a technical consultation to discuss vaccine development. Ultimately, the committee determined that the global burden of GBS disease cases that result in stillbirths needs to be assessed. In addition, standardized antibody assays need to be developed in order to find correlates of protection. Vaccine targets such as the type III capsular polysaccharide (CPS) and proteins on the GBS bacterial surface have also been identified. As new vaccine development ideas for GBS disease are being discussed, here are some foundational components that the Group B Strep Association (US/International) and Group B Strep Support (UK/EU) groups feel have an important role to play in the introduction of the vaccine to pregnant women across the globe:
- Standardized definition of disease worldwide.
- Standardized monitoring of disease worldwide.
- Routine prenatal care widely available in which a vaccine can be delivered.
- Education of health professionals and parents and expectant parents about group B Strep and the vaccine.
Check out these CDC podcasts, if you want to learn additional information about GBS disease during International GBS Awareness Month!