How to Diagnose Scarlet Fever

Scarlet fever is a syndrome caused by toxins produced by the group A beta-hemolytic Streptococcus bacteria. It is contagious and transmitted by the respiratory fluids of an infected person. Scarlet fever caused deadly epidemics in the 19th century before the development of antibiotics. It is no longer widespread and the mortality rate is lower, but outbreaks still occur in the United States.

Difficulty:

Challenging

Instructions

1. Expect an abrupt onset from scarlet fever 1 to 4 days after exposure. The initial symptoms are usually a fever with abdominal pain, fatigue, muscle pain, nausea, sore throat and vomiting.

2. Look for the characteristic bright red rash of scarlet fever to appear 12 to 48 hours after the fever begins.

3. Notice the progression of scarlet fever as the fever peaks as high as 103 to 104 degrees and returns to normal in 5 to 7 days if left untreated. Prompt treatment with antibiotics usually causes the fever to abate within a day.

4. Detect the presence of group A beta-hemolytic Streptococcus with a throat culture. This bacterium can be grown from the culture in 90 percent of the cases during the period of acute infection.

5. Make a clinical diagnosis of scarlet fever based on the symptoms combined with the presence of Streptococcus. The presence of Streptococcus is not sufficient to diagnose scarlet fever because 10 to 15 percent of the people that have this bacterium are merely carriers.