Scarlet fever

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Causes

By Mayo Clinic staff

A bacterium called Streptococcus pyogenes, or group A beta-hemolytic streptococcus, causes scarlet fever. This is the same bacterial infection that causes strep throat, but the strain of bacteria causing scarlet fever releases toxins that produce the rash, Pastia's lines, flushed face and red tongue.

How the infection spreads
Strep bacteria that cause scarlet fever spread from one person to another by fluids from the mouth and nose. If an infected person coughs or sneezes, the bacteria can become airborne, or the bacteria may be present on things the person touches — a drinking glass or a doorknob. If you're near an infected person, you may inhale airborne bacteria. If you touch something an infected person has touched and then touch your own nose or mouth, you could pick up the bacteria.

The incubation period — the time between exposure and illness — is usually two to four days. If scarlet fever isn't treated, a person may be contagious for a few weeks even after the illness itself has passed. And someone may carry scarlet fever strep bacteria without being sick. Therefore, it's difficult to know if you've been exposed.

Scarlet fever strep bacteria can also contaminate food, especially milk, but this mode of transmission isn't as common.

Rare causes of scarlet fever
Rare causes of scarlet fever are other strains of Streptococcus pyogenes associated with either a skin infection (impetigo) or a uterine infection contracted during childbirth. These cases result in the characteristic fever, rash and other "scarlet" signs and symptoms but not those associated with a throat infection.

Risk factors Symptoms

  • See Also

    • Hand Scheduled
  • Impetigo

    • Section Focus
  • Strep throat

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References
  1. Arumugam V, et al. Scarlet fever. In: Ferri FF. Ferri's Clinical Advisor 2009. St. Louis, Mo.: Mosby; 2008. http://www.mdconsult.com/das/book/body/119790350-5/802768093/1701/530.html#4-u1.0-B978-0-323-04134-8..50022-7--cesec71_11163. Accessed Feb. 10, 2009.
  2. Exanthems and drug eruptions. In: Habif TP. Clinical Dermatology. 4th ed. St. Louis, Mo.: Mosby; 2006. http://www.mdconsult.com/das/book/body/119754552-5/802599473/1195/85.html#4-u1.0-B0-323-01319-8..50016-9--cesec21_1617. Accessed Feb. 10, 2009.
  3. Gerber MA. Group A streptococcus. In: Kliegman RM, et al. Nelson Textbook of Pediatrics.18th ed. Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/119754552-5/802599473/1608/526.html#4-u1.0-B978-1-4160-2450-7..50184-5--cesec9_4149. Accessed Feb. 10, 2009.
  4. Streptococcal and enterococcal infections. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merck.com/mmpe/sec14/ch171/ch171d.html. Accessed Feb. 10, 2009.
  5. Scarlet fever. American Academy of Family Physicians. http://kidshealth.org/PageManager.jsp?dn=familydoctor&lic=44&article_set=22939. American Academy of Family Physicians. Accessed Feb. 10, 2009.
  6. Fever in infants and children. American Academy of Family Physicians. http://familydoctor.org/online/famdocen/home/tools/symptom/504.html. Accessed Feb. 10, 2009.
  7. Leslie DL, et al. Neuropsychiatric disorders associated with streptococcal infection: A case-control study among privately insured children. Journal of the American Academy of Child and Adolescent Psychiatry. 2008;47:1166.
  8. Group A streptococcal infections. National Institute of Allergy and Infectious Diseases.  http://www3.niaid.nih.gov/topics/streptococcal/default.htm. Accessed Feb. 10, 2009.
  9. Scarlet fever. Centers for Disease Control and Prevention. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/scarletfever_g.htm. Accessed Feb. 10, 2009.
  10. PANDAS. Pediatrics & Developmental Neuroscience Branch. http://intramural.nimh.nih.gov/pdn/web.htm. Accessed Feb. 10, 2009.

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April 4, 2009

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