12. Pediatric illnesses accompained by rash.

Page created on February 9, 2022. Last updated on March 23, 2022 at 16:49


Measles is caused by the measles virus, a paramyxovirus. Nowadays it’s uncommon thanks to the MMR vaccine, but outbreaks continue to occur. Older children tend to have more severe disease than young. It’s highly infectious and is transmitted by droplet spread.

Clinical features include the 4 C’s: coryza, conjunctivitis, cough, and Koplik spots, which are white spots on the buccal mucosa, as well as fever and rash. This red maculopapular rash spreads from the face downwards.

Measles is self-limiting, but can rarely cause severe complications, including encephalitis (after a few days) or subacute sclerosing panencephalitis (SSPE), which occurs years after the infection.

Vitamin A deficiency worsens the outcome of measles. WHO therefore recommends administration of vitamin A to all children with measles. Ribavirin can be used in severe cases.


Rubella is caused by the rubella virus, a togavirus. Like measles, rubella is also rare thanks to the MMR vaccine. It’s also called German measles thanks to its clinical similarity to measles and that a German doctor first described it. Rubella is generally a mild disease.

Clinical features are similar as for measles, but with generalised tender lymphadenopathy. Treatment is supportive.

Varicella zoster

Varicella zoster, also called chickenpox, is caused by varicella zoster virus. It’s highly infectious and is characterised by an itchy vesicular rash which begins on the head and trunk and spread from there. It’s typical that there are lesions in different stages of healing present simultaneously.

Varicella zoster is self-limiting but can rarely cause severe complications. These include secondary bacterial infection, encephalitis, and disseminated disease (in the immunocompromised). It’s self-limiting, but immunocompromised should be treated with acyclovir.

Scarlet fever

Scarlet fever is a delayed-type hypersensitivity reaction to the group A streptococcus (GAS) toxin. It’s characterised by strawberry tongue, circumoral pallor, and a diffuse maculopapular rash which gives a “sandpaper” quality to the skin. It occurs shortly after streptococcal pharyngitis. Antibiotics (penicillin or amoxicillin) are given, not primarily to hasten recovery but to prevent complications like rheumatic fever and glomerulonephritis.

Exanthema subitum

Exanthema subitum, also called roseola infantum, is caused by HHV6 or 7. It is characterised by a high fever which is followed by a generalised macular rash as the fever subsides. It’s self-limiting, and treatment is supportive.

Exanthema infectiosum

Exanthema infectiosum, also called fifth disease or slapped cheek syndrome”, is caused by parvovirus B19. IT’s characterised by fever and a characteristic rash on the face which makes it look like the cheek has been slapped. It’s self-limiting, and treatment is supportive. In patients with sickle cell disease or thalassaemia, parvovirus B19 causes an aplastic crisis, which necessitates transfusions until the aplasia has subsided.

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2 thoughts on “12. Pediatric illnesses accompained by rash.”

  1. Ay bro, I had my exam and got the paediatric rashes question, turns out we need to know both infectious and non infectious diseases that cause rashes. Luckily I knew about some allergies that the topic here didnt mention here.
    Also we need to mention that currently Scarlet fever is the most common contagious cause since it has no vaccine

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