Infection: Strep Throat

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Infection: Strep Throat


Strep throat is an acute infection of the throat caused by the same type of bacterium (group A streptococcus) that causes scarlet fever.


Strep throat is an infectious disease that may affect adults as well as children. It is spread by fluids from the throat or nose of an infected person or by contact with a drinking glass, soiled tissue, or other object touched by an infected person. In a very few cases, the bacteria that cause strep throat have been spread by contaminated food.

The incubation period of strep throat is short, usually between two and five days. The symptoms often come on rapidly, with the patient developing a sore throat that may make swallowing or speaking difficult. The fever is usually highest on the second day of illness.


The bacterium that causes strep throat is common around the world. It is responsible for 25–30 percent of the ten million cases of severe sore throat that doctors treat in the United States each year.

Strep throat can occur at any time of the year but is most common in North America in the late winter and early spring. It is more likely to occur in children between the ages of five and fifteen than in adults; it is less common in children younger than two years of age. Strep throat affects males and females equally, and appears to be equally common in all races and ethnic groups.

Causes and Symptoms

Strep throat is caused by a bacterium—a group A streptococcus that normally lives in the upper respiratory tract. As the bacteria grow in the tissues of the nose and throat, they may secrete toxins that may cause skin rashes in some patients with strep throat in addition to the fever and other symptoms.

In addition to a sore throat of sudden onset, the symptoms of strep throat include:

  • Fever of 101°F (38.3°C) or higher
  • Headache
  • Chills and cold sweats
  • Nausea and vomiting (more common in children)
  • Difficulty swallowing
  • Red and swollen tonsils, sometimes with yellow or whitish-grey streaks of pus
  • Bad breath
  • Rash or hives
  • Loss of appetite
  • Abdominal cramps
  • Enlarged glands in the neck that are sore to the touch
  • Aching muscles or sore joints


Correct diagnosis of strep throat is important because most sore throats are caused by viruses rather than the bacteria that cause strep throat. Sore throat caused by viruses should not be treated with the antibiotics used for strep throat.

The diagnosis of strep throat is usually based on a combination of the patient'shistory—particularly recent exposure to other children with a streptococcal infection—and the doctor's examination of the patient's throat, neck glands, and skin. The doctor may also take a sample of fluid from the child's throat on a cotton swab. The fluid can be sent to a laboratory for a throat culture, which is an accurate test that takes two days. The doctor may also perform what is called a rapid strep test. It can detect proteins produced by the streptococci in a few minutes in the doctor'soffice. The rapid strep test, however, is not as accurate as a throat culture.


Patients with a known case of strep throat are treated with a course of antibiotics, most commonly penicillin, azithromycin, or a similar drug known to be effective in treating streptococcal infections. A child whose

throat is too sore to allow comfortable swallowing can be given penicillin by injection.

A child with strep throat will usually not be contagious within a day or two of starting treatment and can return to school once the fever goes down. It is important, however, for anyone, child or adult, with strep throat to take the full course of antibiotics (usually ten days), even though he or she may start to feel better in a few days. Not taking the full course of antibiotics may lead to such later complications of strep throat as rheumatic fever or inflammation of the kidneys. The doctor should be consulted if the patient does not begin to feel better after a day or two of antibiotic treatment.

Adults or children with strep throat can take ibuprofen, acetaminophen, or another nonaspirin pain reliever to bring down fever and relieve muscle cramps or headache. Gargling with salt water—one-half teaspoon of salt in a glass of warm water—is recommended for easing the throat discomfort.

In some cases, the doctor may recommend a tonsillectomy to prevent recurrence of streptococcal infections. A study done in 2006 found that children with repeated episodes of strep throat whose tonsils are intact are more than three times as likely to develop additional episodes of strep throat than children whose tonsils were removed.


The great majority of patients with strep throat recover completely with no complications even without antibiotic treatment. However, about two patients per 1,000 who are not treated will develop rheumatic fever and another two per 1,000 will develop a severe infection of the tonsils. Other possible but rare complications of strep throat include ear infections, kidney or liver damage, pneumonia, inflammation of the bones or joints, or sinusitis.

Another possible complication of strep throat is the PANDAS syndrome, a term that stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. Some children develop symptoms of obsessive-compulsive disorder or Tourette syndrome after a group A streptococcal infection; or they become moody, irritable, and anxious when separated from their parents. The connection between these symptoms and the infections is not clear, however, and many doctors think that further research is needed.


Strep throat is difficult to prevent completely because of the close contact among children in schools and day care centers, particularly in the winter. In addition, some people can carry Group A streptococci in their throats without getting sick themselves. When anyone in a family is diagnosed with strep throat, doctors recommend protecting other members by washing the sick person's eating utensils, drinking glasses, and bedding in hot soapy water separately from the rest of the family's dishes and laundry. Children with strep throat should also be reminded to cover the nose and mouth when sneezing or coughing and to wash the hands thoroughly in warm soapy water afterward.

The Future

As of 2008 the chief concern among doctors was the overuse of antibiotics in treating strep throat. Across the United States, 70 percent of children with sore throats who are seen by a doctor are treated with antibiotics even though 30 percent at most have strep infections. It can be difficult to distinguish between bacterial and viral infections of the throat even when a throat culture is performed because some people may be carriers of group A streptococci and have the bacteria in their throat at the same time that they have a sore throat caused by a virus.

The chief danger of overuse of antibiotics is the creation and spread of drug-resistant disease organisms. In addition, some people can have severe allergic reactions to antibiotics. To guard against overprescribing antibiotics for sore throats that may not be caused by streptococci, many doctors now follow a two-step procedure for diagnosing strep throat before giving the patient a prescription for antibiotics. They give the patient a rapid strep test in the office; if the result is positive, the doctor then takes a throat swab and sends it for a culture. If that test too comes back positive, the patient is then given antibiotics. Waiting two days for antibiotic treatment will not increase the patient's risk of developing complications from strep throat.

SEE ALSO Rheumatic fever; Scarlet fever


Group A streptococcus: A sphere-shaped bacterium that grows in long chains and causes strep throat as well as scarlet fever.

PANDAS disorders: A group of disorders with psychiatric symptoms that develop in some children after strep throat or scarlet fever. The acronym stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections.

Pharyngitis: The medical term for sore throat.

For more information


Glaser, Jason. Strep Throat. Mankato, MN: Capstone Press, 2007.

Laskey, Elizabeth. Strep Throat. Chicago, IL: Heinemann Library, 2003.

Smith, Tara C. Streptococcus (Group A). Philadelphia: Chelsea House Publishers, 2004.


Brody, Jane. “Strep Symptoms: When to Use Antibiotics.” New York Times, October 10, 2006. Available online at (accessed June 12, 2008).


Centers for Disease Control and Prevention (CDC). Group A Streptococcal (GAS) Disease. Available online at (accessed June 13, 2008).

Mayo Clinic. Strep Throat. Available online at (accessed June 12, 2008).

National Institute of Allergy and Infectious Diseases (NIAID). Group A Streptococcal Infections. Available online at (accessed June 13, 2008).

TeensHealth. Strep Throat. Available online at (accessed June 13, 2008).

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Infection: Strep Throat

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