Newsfeed display by CaRP Group B streptococcal (GBS) disease is caused by the bacterium Streptococcus agalactiae that can cause illness in newborn babies, pregnant women, the elderly and people with weakened immune systems. GBS disease is the most common cause of life-threatening infections in newborns.

Before prevention efforts were widely used, approximately 8,000 babies in the United States would be infected with GBS each year, and approximately 5% of those infected would die from the infection. It is currently estimated that 20-25% of pregnant women carry GBS in their rectum or vagina, and 1-2% of babies whose mother carry GBS will develop signs and symptoms of the disease. Most of these cases develop within the first week of birth ("early-onset disease"). GBS disease may also develop in infants 1 week to several months after birth ("late-onset disease"), but is less common. Sepsis (blood infection), pneumonia and meningitis (infection of the fluid and lining surrounding the brain) are the most common illnesses identified in newborns.

In pregnant women, GBS can cause bladder infections, womb infections such as amnionitis and endometritis, and death of the fetus. Among other people that acquire GBS disease, the most common complications are blood infections, skin or soft tissue infections, and pneumonia.

Many people carry the GBS bacteria on their bodies but do not become ill. These people are considered "carriers" but typically are only temporarily colonized with the bacteria. Adults can carry GBS in the bowel, bladder or throat. A fetus most commonly becomes infected before or during birth. Person to person transmission is rare. Babies born before 37 weeks gestation or more than 18 hours after amniotic membranes have ruptured are at an increased risk for developing GBS disease

GBS disease is diagnosed when the Streptococcus agalactiae bacterium is grown from cultures of sterile body fluids, such as blood or spinal fluid. GBS infections in both newborns and adults are usually treated with antibiotics.

How can GBS disease be prevented? Screening pregnant women for Streptococcus agalactiae at 35-37 weeks gestation, and treating those who carry the bacteria with antibiotics when they begin labor can prevent GBS disease in infants. There is no vaccine to prevent GBS disease.