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Medical Author:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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In this Article

• Scarlet fever facts
• What is scarlet fever?
• What is the history of scarlet fever?
• What causes scarlet fever?
• What are scarlet fever symptoms and signs?
• How long is scarlet fever contagious?
• How is scarlet fever diagnosed?
• What is the treatment for scarlet fever?
• Can scarlet fever be prevented?
• What is the prognosis for scarlet fever?
• Find a local Doctor in your town
• Scarlet Fever Index

Scarlet fever is caused by the Gram-negative coccal-shaped bacterium Streptococcus pyogenes, also known as group A streptococci (GAS). This is the same bacterium that causes ordinary strep throat and which is associated with other diseases such as rheumatic fever. However, in order to cause scarlet fever, the infecting strain of S. pyogenes must produce a specific protein toxin. This toxin that causes scarlet fever is known as "erythrogenic toxin" or "pyrogenic toxin." It causes a reaction in skin that leads to the typical rash.

Scarlet fever usually starts abruptly with a sore throat and fever. Headache, enlarged lymph nodes in the neck, and fatigue are common. Younger children may complain of abdominal pain or have vomiting. On examination, the throat is inflamed and there may be patches of yellow pus (exudates) on the back of the throat. Although most cases of scarlet fever start with a sore throat, a small proportion arises from streptococcal infection of a wound.

Within two days of onset, a rash begins to appear. The rash usually starts on the chest and trunk then spreads to the arms and legs. The rash does not usually appear on the palms or soles. The face may be flushed, except for a pale area around the lips (circumoral pallor). In places where there are skin creases such as elbows, the rash may cause deep red lines known as Pastia's lines. The typical rash is diffusely red and blanches when pressed, but there may be areas with small cherry-red dots known as "petechiae" that do not blanch. Petechiae may also be seen inside the mouth on the palate. When the rash is present, the skin has small bumps and may feel rough like sandpaper (see Figure 1).

Figure 1: Picture of scarlet fever rash on arm; Source: CDC

After two to four days, the rash begins to fade. At this time, the skin may start to peel and flake (desquamation), looking like the aftermath of a bad sunburn. Desquamation is particularly noticeable on the face and hands.

In addition to the skin rash, the tongue initially appears to be coated with a white substance through which red papillae may be seen. This is called a "white strawberry tongue." After two to four days, the coating sloughs off, leaving a bright red tongue with red papillae, called the "red strawberry tongue."