Exanthemata with you?

Among the most common conditions we encounter in pediatrics are rashes. They can have a number of causes including drugs and toxins (as in poison ivy), but today I want to discuss the rashes caused by certain infections.

Classically childhood rashes caused by infectious agents were numbered. The numbering was first provided in 1905 and is as follows:

  1. First disease is rubeola, aka measles. Measles is caused by measles virus which is highly contagious. It develops 10-20 days after exposure and lasts 7-10 days. Initially the infected person will develop high fever (up to 104 degrees), cough, runny nose, and inflamed eyes. White spots called Koplik’s spots appear in the mouth about 3 days into the infection. A diffuse rash appears on the face and spreads throughout the body three to five days after the start of symptoms. In about a third of patients complications such as blindness, encephalitis, and pneumonia will develop. Also, a recent study revealed that measles infection can make the patient susceptible to other diseases by erasing the immunologic memory your body has developed over time. Thankfully vaccination has made the disease rare.
  2. Second disease is scarlet fever. Scarlet fever is an infection caused by group A streptococcus. This can be strep throat or impetigo. The cause is an erythrogenic toxin which leads to a rough, sandpaper like rash which typically begins in the groin and folds of the arms and legs. Complications of scarlet fever include rheumatic heart disease and glomerulonephritis. Antibiotic therapy, usually penicillin, will treat the infection and protect against rheumatic heart disease. After the rash resolves the skin may peel in a manner similar to a sunburn.
  3. Third disease is rubella which is caused by rubella virus. It is also known as German measles or three day measles. It is a mild infection in which the rash appears about two weeks after infection and lasts for three days. There may be sore throat and fever present as well as joint swelling. The most significant problem resulting from rubella is congenital rubella syndrome. This occurs when a non-immune mother contracts rubella while she is pregnant. This can lead to miscarriage, cataracts, deafness, and congenital heart disease. Thankfully this disease is rare due to vaccination with the MMR vaccine.
  4. Fourth disease is Dukes’ disease. It is an entity that there is some question as to it’s etiology. The prevailing opinion at this time is that it is staphylococcal scalded skin syndrome. This is a rash that appears similar to a sunburn that will occasionally have blisters. It is treated with pain relievers and antibiotics.
  5. Fifth disease is called erythema infectiosum. It is caused by human parvovirus B19. In most people this is a mild infection which first manifests in bright redness to the cheeks hence one of its common names, the “slapped cheek disease”. As time passes the redness of the cheeks fades and a lacy rash appears on the upper and lower extremities. The patient is actually contagious during the asymptomatic period. Once the rash appears it is no longer contagious. In adults and teenagers swelling of joints may occur. The most significant complication with fifth disease is in those who have sickle-cell anemia. These people undergo what is called aplastic crisis. This is characterized by a profound anemia. A pregnant mother who is not immune may also have complications such as congestive heart failure in her baby,
  6. Sixth disease is called roseola infantum. It is cause by human herpesvirus 6 and human herpesvirus 7, and if affects children mainly 6 months to 2 years. It presents with fever, up to 104. The fever lasts a few days, and shortly after the fever breaks, a non-itching rash develops on the trunk and spreads outward. This lasts 1-2 days and then vanishes.

Thank goodness the conditions which we mainly deal with are numbers 2, 5, and 6, but these are only the numbered exanthemata. There are many illnesses which cause rashes.  In fact, just about any viral infection can cause a rash.  However, if your child has an unexplained rash, one that wont go away, or worsens, they should be checked to be safe.

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