I had heard of Scarlet Fever, but to be honest I didn’t know what it was. A faded memory from microbiology classes long past. Recently, a friend of mine got it so I decided to look it up. Scarlet Fever, it turns out, is a sequela (plural = sequelae) of Strep Throat. A sequela is a complication of another disease or condition, kind of like a side effect.

My friend’s young son got Strep Throat, and like a good parent, he got it too. Then he developed Scarlet Fever. Scarlet Fever is a rough, red rash on the skin. You can also get red bumps on your tongue that make it look like a strawberry.


Scarlet fever rash on the torso

Body Rash of Scarlet Fever. Wikimedia Commons.


Strawberry tongue of Scarlet Fever.

Strawberry tongue of Scarlet Fever. Wikimedia Commons.

That’s called—you guessed it–Strawberry tongue. It’s usually seen in young children, but my friend is one of the lucky adults to come down with it. Only a small percentage of people who get Strep Throat or another streptococcal disease develop Scarlet Fever. This suggests to me that there may be a host (or genetic) factor or factors that play a role in developing Scarlet Fever, but I don’t know that for sure.

Strep Throat is caused by a bacteria called Streptococcus pyogenes, or Strep pyogenes. Strep pyogenes is a member of a family of bacteria called Group A Strep. Strep pyogenes bacteria are commonly found on our skin. These bacteria cause a number of nasty diseases, such as Toxic Shock Syndrome, Rheumatic Fever, and necrotizing fasciitis, the flesh eating disease.

Long strings of spherical bacteria are characteristic of Streptococci.

Illustration of Streptococcus bacteria based on a photomicrograph. S. Anderson. Long strings of spherical bacteria are characteristic of Streptococci. Strepto = twisted chain; Coccus = spherical.

Strep pyogenes bacteria produce several toxins that help them cause disease. These toxins are known as virulence factors. The virulence factors that lead to Scarlet Fever are three toxins called SPE-A, SPE-B, and SPE-C. SPE stands for Streptococcal Pyrogenic Exotoxin. “Pyrogenic” means they cause fever. SPE-A, B, and C were formerly called erythrogenic toxins. “Erythrogenic” means “causing redness”, as seen in Scarlet Fever.

Strep Throat and Scarlet Fever are not normally serious or life-threatening, and can be treated with antibiotics like penicillin. However, if left untreated, they can lead to some serious sequelae (see what I did there) such as Rheumatic Fever, kidney disease, even lung infection, and arthritis. So if you think you or your child or loved one might have Strep Throat–GET TO THE DOCTOR!


Todar, K. Todar’s Online Textbook of Bacteriology www.textbookofbacteriology.net. Streptococcus pyogenes and Streptococcal Disease, p. 2. http://textbookofbacteriology.net/streptococcus_2.html. Accessed June 7, 2015.

Centers for Disease Control and Prevention (CDC). Scarlet Fever: A Group A Streptococcal Infection. http://www.cdc.gov/features/scarletfever/. Accessed June 7, 2015.

Streptococcus pyogenes. http://en.wikipedia.org/wiki/Streptococcus_pyogenes. Accessed June 7, 2015.


Strawberry tongue of Scarlet Fever. Attribution: 6 Mar 2006: Erdbeerzunge Himbeerzunge Scharlach. Foto von Martin Kronawitter, Kellberg; 22 July 2013, color adjust by Jbarta; via Wikimedia Commons.

Body Rash of Scarlet Fever. Attribution: By The original uploader was Estreya at English Wikipedia (Transferred from en.wikipedia to Commons.) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5), via Wikimedia Commons.