First to seventh diseases: discarded diagnoses?

BMJ 2015; 351 doi: (Published 27 July 2015) Cite this as: BMJ 2015;351:h3525
  1. Mitesh Patel, academic foundation year 2, general practice, Hampton Surgery, Solihull,
  2. Rodger Charlton, professor of primary care, University of Nottingham
  1. mpatel59{at}

A mother brought in her 5 year old child with a rash, asking, “Doctor, is this fifth disease?” Good question, but could it be one of the other six, and why are these childhood exanthema diagnostic terms mostly not used, other than “fifth disease”?

Let’s start at the beginning. “First disease” (measles), first scientifically described around the 10th century, is caused by measles virus. A maculopapular rash initially presents on the face and behind the ears. Bluish white Koplik’s spots may be seen on the inner cheek.

“Second disease” (scarlet fever), caused by Streptococcus pyogenes, was identified in 1553 with a “sandpaper”-like fine, papular rash starting on the neck and groin prior to desquamation. The “white strawberry” coating on the tongue peels to give a “red raspberry” tongue.

“Third disease” (rubella or German measles), recognised in 1881, is caused by rubella virus. A rash of pink macules and papules on the face descends. Forschheimer spots may be seen over the uvula and soft palate. Generalised, tender lymphadenopathy is a key characteristic.

In 1900 Clement Dukes claimed the existence of the controversial “fourth disease,” comprising a generalised maculopapular rash and desquamation. The lack of differentiation from the previous exanthemas and of a causative organism means that its existence remains in doubt. This exanthema may be staphylococcal scalded skin syndrome.

In 1905 erythema infectiosum (nicknamed “slapped cheek”), caused by parvovirus B19, was called “fifth disease.” Confluent, coalescing erythematous patches on the cheeks spare the nasal bridge, spreading with a lacy, reticular rash.

Roseola infantum became “sixth disease” in 1910, caused by human herpesvirus 6 or 7 and occurring after a sudden high fever and therefore also called exanthema subitum (“sudden rash”). Small pale pink macules and pustules with white halos are seen on the trunk, arms, and neck.

In 1979 and 2001 there was recognition of a possible “seventh disease,” after Kawasaki’s 1967 report in Japan of a “new” condition also referred to as acute febrile infantile mucocutaneous lymph node syndrome (MCLS). The cause is not clear, but it can present with a polymorphous truncal rash, erythema, and desquamation affecting the extremities.

With the detection of the infective markers causing exanthemas, further numeration may be deemed impractical. But where does that leave the commonly known exanthema chicken pox? Why is it so called and why did it not receive a number? And doubtless there will always be a mother who asks, “Is it anything to do with chickens?”


Cite this as: BMJ 2015;351:h3525

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