Group A streptococcal (GAS) infections can range from a mild skin infection or a sore throat to severe, life-threatening conditions. Most people are familiar with strep throat, which along with minor skin infections, is the most common form of the disease.

Why Is the Study of Group A Streptococcal Infections a Priority for NIAID?

Health experts estimate that more than 10 million mild infections (throat and skin) occur every year.

Biology & Genetics

Through research, health experts have learned that there are more than 120 different strains of group A streptococci bacteria, each producing its own unique proteins. Some of these proteins are responsible for specific GAS diseases. With the support of NIAID, scientists have determined the genetic sequence, or DNA code, for five strains of the group A streptococcus bacterium. By studying its genes, scientists can learn which proteins are responsible for virulence—crucial information that will lead to new and improved drugs and vaccines.

Vaccines

NIAID supports research to develop a group A streptococcus vaccine, and several candidate vaccines are in various phases of development. While some scientists are conducting animal model studies to obtain data to pursue clinical trials in humans, other scientists are close to evaluating group A streptococcus vaccine candidates in Phase I clinical trials.

Types of GAS Infections

Group A streptococcal (GAS) infections can range from a mild skin infection or a sore throat to severe, life-threatening conditions. Most people are familiar with strep throat, which along with minor skin infections, is the most common form of the disease. Health experts estimate that more than 10 million mild infections (throat and skin) occur every year.

Cellulitis and Erysipelas

Cellulitis is inflammation of the skin and deep underlying tissues. Erysipelas is an inflammatory disease of the upper layers of the skin. Group A strep (streptococcal) bacteria are the most common cause of cellulitis and erysipelas.

Impetigo

Impetigo is an infection of the top layers of the skin and is most common among children ages 2 to 6 years. It usually starts when bacteria get into a cut, scratch, or insect bite.

Scarlet Fever

Scarlet fever – or scarlatina – is a bacterial infection caused by group A Streptococcus or "group A strep." This illness affects a small percentage of people who have strep throat or, less commonly, streptococcal skin infections.

Severe Strep Infections

Some types of group A strep bacteria cause severe infections, such as

  • Bacteremia (bloodstream infections)
  • Toxic shock syndrome (multi-organ infection)
  • Necrotizing fasciitis (flesh-eating disease)
Strep Throat

Many things can cause that unpleasant, scratchy, and sometimes painful condition known as a sore throat. Viruses, bacteria, allergens, environmental irritants (such as cigarette smoke), chronic postnasal drip, and fungi can all cause a sore throat. While many sore throats will get better without treatment, some throat infections—including strep throat—may need antibiotic treatment.

Source: National Institutes of Health; National Institute of Allergy and Infectious Diseases