Strep throat is an infection caused by the bacterium, Streptococcus pyogenes. It is spread through person-to-person contact with contaminated nasal secretions or respiratory droplets. Symptoms usually occur within three days of exposure. Patients may experience throat inflammation and pain, swollen lymph nodes in the neck, fever, headache, chills, body aches, muscle aches and abdominal pain. Inside, the throat may look red with white or yellowish spots.

According to the National Institute of Allergy and Infectious Diseases, more than 10 million sore throats occur every year. Most sore throats are caused by a viral infection. Strep is the most common bacterial cause of sore throat. Incidence is highest among children 5 to 15. Although it can occur at any time of the year, strep outbreaks most frequently happen during late fall, winter and early spring.

If strep is suspected, a doctor may order a throat culture (rapid tests are available, but are not as sensitive in detecting the strep bacteria). It can take a day or two to get the results back from the lab. In the meantime, the physician may prescribe antibiotics to fight the infection. If the lab results are negative for strep, the patient can stop taking the antibiotics.

It's important for patients with strep throat to receive treatment for the condition. After 24 hours of initiating treatment, antibiotics will help ease symptoms and prevent the infection from being spread to others.

If strep is not treated within 9 days, the infection can lead to the development of rheumatic fever, a condition that can cause joint pain, heart muscle inflammation, heart failure and kidney problems. Rheumatic fever may develop within 18 days of an untreated strep throat.

Strep Carriers

Strep is very common in children. Recently, researchers at Children's Hospital of Pittsburgh found 60 percent of school-aged children in their area tested positive for the infection at least once during the school year. Despite the high prevalence, a little more than half didn't show any signs of infection. These children are carriers of the strep bacteria. Investigators say the carriers can harbor the bacteria for months or years without ever getting sick. In addition, a carrier may actually have more than one strain of strep at a time.

Antibiotics can't kill the strep bacteria in an asymptomatic carrier because the bacteria are dormant and not susceptible to the drugs. However, the decision to treat or not treat becomes more difficult when a carrier develops symptoms of strep throat. A throat culture isn't an accurate indication of the diagnosis because a carrier will always test positive for strep. If the symptoms are caused by a virus, antibiotics will have no effect against the new infection. On the other hand, if the child has acquired a new strep infection, antibiotics are needed to prevent development of rheumatic fever. Since a throat culture can't differentiate between strains of the bacteria (i.e., an old vs. a new infection), investigators say it may be wise to err on the side of caution and prescribe antibiotics.

For information on strep throat:

American Academy of Pediatrics Centers for Disease Control and Prevention KidsHealth® National Institute of Allergy and Infectious Diseases