Red flags for childhood rashes

3 minute read

The colour red has been forever associated with childhood rashes and their treatments.

Several red-rash diseases of childhood have recently surged around the world including measles, scarlatina and apparent new diseases too.

A new and serious childhood hepatitis emerged in 2022.  Most cases are associated with adenovirus (particularly HAdV-F41), another cause of red rashes, but some cases are associated with SARS -CoV-2 coinfection. Hepatitis may present with red rash, especially a pruritic urticaria.

Another recently “discovered” red rash – “Kerala tomato flu” – is actually hand, foot and mouth disease, typically caused by either of two members of the enterovirus genus (coxsackievirus CVA-16 or enterovirus EV-A71).

For centuries, doctors have been trying to correctly identify, then name and number, the causes of red rashes of childhood.

First was measles, also called rubeola – which means red and is the beginning of the ingenious naming (by us clever doctors) of a rash as red – using an array of different words that all just mean red. Always impress the patient with strange medical terminology! Then endeavour to prescribe the best treatments. 

Hippocrates (460-377BC) wrote about two possible, yet contradictory treatment principles – contrarania contrariis curantur, meaning opposites are used to treat opposites – cold presses on hot swellings, for example – and similia similibus curentur, where like treats like. Heat applied to hot lesions, for example.

Over time, both methods found favour among physicians. Hence the origin of associating and/or using red to treat red rashes and lesions.

By the 17th century, “the red treatment” was popularised in many cultures, including Europe. Smallpox sufferers and their surroundings were decorated with red cloth in the belief the colour combatted the disease. By the 1800s, refinement led to the “red light treatment”, which persisted through World War I. The association with red is believed to explain why red blankets persisted in infectious diseases hospitals into the 20th century.

But let’s get back to the present.

Listed historically and in succession from first to sixth, the major diseases presenting with red rashes (with some notable features) are:

1. Measles – rubeola: look for early Koplik spots in mouth; known for a millennium;

2. Scarlet fever – scarlatina: a flat, confluent, sand-paper rash that later, like Kawasaki’s, desquamates;

3. Rubella – “3-day measles”; a teratogen; known for over a century;

4. Duke’s disease – was not a separate entity but a menagerie of Staphylococcal scalded skin syndrome, scarlatina and rubella;

5. Erythema infectiosum, slapped cheek syndrome, parvovirus B19;

6. Roseola infantum – conveniently due to human herpesvirus 6A and 6B, but also HHV-7; also known as exanthem subitem; both associated with febrile fits.

Both meningococcal and streptococcal bacterial diseases have also recently surged in 2022-23, (secondary to the rises in respiratory viral diseases, increased community mixing and an immunological deficit from reduced mixing of people during the covid years). Both can be rapidly invasive and deadly, and characteristic rashes may ensue (petechial and red/purple, or scarlatinic and red). 

For now, the important and extraordinary role of the GP in the early diagnosis and best management of the myriads of red rashes currently presenting to primary care is to be lauded and supported with more paid opportunities to learn and interact.

Professor Robert Booy is an infectious disease paediatrician at the University of Sydney.

Dr Sue Rodger-Withers is a virologist with the University of Melbourne, Victoria University and Fairfield Hospital for Infectious Diseases.

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