Most cases of sore throat are caused by viruses, generally the same viruses that cause colds. One familiar type of sore throat, however, is caused by bacteria in the streptococcus family: streptococcal pharyngitis, commonly known as strep throat. It is relatively common in children.
Symptoms of strep throat include intense throat pain (generally developing suddenly), difficulty swallowing, and fever ranging from 101°F to 104°F. In children, headache, abdominal pain, nausea, and vomiting may also occur. The back of the throat generally (but not always) becomes beefy red in color, possibly with white or red dots. However, none of these signs or symptoms is absolutely characteristic of strep throat. In some cases, none of these symptoms is present. Ultimately, diagnosis of strep throat must be made through a laboratory examination of material swabbed from the back of the throat.
The primary significance of strep throat is not the throat infection itself, but rather a delayed complication called rheumatic fever. Strep throat itself will disappear in 3 to 5 days even without treatment. However, when a certain group of streptococcal bacteria are involved, called
Group A beta-hemolytic streptococci
, there is risk of a severe, dangerous complication developing about 1 to 5 weeks later, when all seems to be well. This is the feared second effect of strep throat known as rheumatic fever.
The initial attack of rheumatic fever involves five major signs and symptoms:
- Carditis—inflammation of the heart, often causing a heart murmur
- Chorea—rapid, purposeless, nonrepetitive movements that are not under conscious control
- Migratory polyarthritis—severe joint pain, redness, and swelling that moves from joint to joint
- Subcutaneous nodules—nodules under the skin
- Erythema marginatum—a serpentine, flat rash
These symptoms will eventually subside. However, when they are gone, the valves of the heart may be permanently damaged, necessitating open heart surgery.
About 3% of untreated Group A beta-hemolytic strep throat cases lead to rheumatic fever.
Children ages 4 to 15 are most at risk. Adults with strep throat may develop rheumatic fever, but the chance is extremely low. Rheumatic fever is rare in the US because of prompt treatment of strep throat, but it is not rare in developing countries, where it is one of the leading causes of heart disease.
The cause of rheumatic fever is interesting. It is thought that certain strains of strep bacteria contain glycoproteins that, from the perspective of the immune system, resemble glycoproteins found in the heart, joints, and/or nerve tissue. When the body makes antibodies to attack the strep bacteria, those antibodies also damage the body.
The only known way to prevent rheumatic fever in people with strep throat involves using antibiotics at relatively high doses and for a prolonged period of time. The goal is to entirely eradicate the invading bacteria, so that the body does not feel a need to make antibodies against it.