Streptococcal pharyngitis

The typical signs and symptoms of streptococcal pharyngitis are a sore throat, fever of greater than 38 °C (100 °F), tonsillar exudates (pus on the tonsils), and large cervical lymph nodes.[10]

Other symptoms include: headache, nausea and vomiting, abdominal pain,[11] muscle pain,[12] or a scarlatiniform rash or palatal petechiae, the latter being an uncommon but highly specific finding.[10]

Symptoms typically begin one to three days after exposure and last seven to ten days.[3][10]

Strep throat is unlikely when any of the symptoms of red eyes, hoarseness, runny nose, or mouth ulcers are present. It is also unlikely when there is no fever.[8]

• 
  Mouth wide open showing the throat
  A throat infection which on culture tested positive for group A streptococcus. Note the large tonsils with white exudate.
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  Mouth wide open showing the throat
  Note the petechiae, or small red spots, on the soft palate. This is an uncommon but highly specific finding in streptococcal pharyngitis.[10]
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  A set of large tonsils in the back of the throat, covered in white exudate.
  A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in an 8-year-old.

Strep throat is caused by group A β-hemolytic Streptococcus (GAS or S. pyogenes).[13] Humans are the only known natural reservoir for group A streptococcus.[14] Other bacteria such as non–group A β-hemolytic streptococci and fusobacterium may also cause pharyngitis.[10][12] It is spread by direct, close contact with an infected person; thus crowding, as may be found in the military and schools, increases the rate of transmission.[12][15] Dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days.[12] Contaminated food can result in outbreaks, but this is rare.[12] Of children with no signs or symptoms, 12% carry GAS in their pharynx,[7] and, after treatment, approximately 15% of those remain positive, and are true "carriers".[16]

A number of scoring systems exist to help with diagnosis; however, their use is controversial due to insufficient accuracy.[17] The modified Centor criteria are a set of five criteria; the total score indicates the probability of a streptococcal infection.[10]

One point is given for each of the criteria:[10]

• Absence of a cough
• Swollen and tender cervical lymph nodes
• Temperature >38.0 °C (100.4 °F)
• Tonsillar exudate or swelling
• Age less than 15 (a point is subtracted if age >44)

A score of one may indicate no treatment or culture is needed or it may indicate the need to perform further testing if other high risk factors exist, such as a family member having the disease.[10]

The Infectious Disease Society of America recommends against routine antibiotic treatment and considers antibiotics only appropriate when given after a positive test.[8] Testing is not needed in children under three as both group A strep and rheumatic fever are rare, unless a child has a sibling with the disease.[8]

Tonsillectomy may be a reasonable preventive measure in those with frequent throat infections (more than three a year).[22] However, the benefits are small and episodes typically lessen in time regardless of measures taken.[23][24][25] Recurrent episodes of pharyngitis which test positive for GAS may also represent a person who is a chronic carrier of GAS who is getting recurrent viral infections.[8] Treating people who have been exposed but who are without symptoms is not recommended.[8] Treating people who are carriers of GAS is not recommended as the risk of spread and complications is low.[8]

Untreated streptococcal pharyngitis usually resolves within a few days.[10] Treatment with antibiotics shortens the duration of the acute illness by about 16 hours.[10] The primary reason for treatment with antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses.[10] Antibiotics prevent acute rheumatic fever if given within 9 days of the onset of symptoms.[13]

The symptoms of strep throat usually improve within three to five days, irrespective of treatment.[20] Treatment with antibiotics reduces the risk of complications and transmission; children may return to school 24 hours after antibiotics are administered.[10] The risk of complications in adults is low.[8] In children, acute rheumatic fever is rare in most of the developed world. It is, however, the leading cause of acquired heart disease in India, sub-Saharan Africa, and some parts of Australia.[8]

Complications arising from streptococcal throat infections include:

The economic cost of the disease in the United States in children is approximately $350 million annually.[8]

Pharyngitis, the broader category into which Streptococcal pharyngitis falls, is diagnosed in 11 million people annually in the United States.[10] It is the cause of 15–40% of sore throats among children[7][10] and 5–15% in adults.[8] Cases usually occur in late winter and early spring.[10]