Childhood exanthems

Disease	Season	Rash	Associated Findings
measles	winter to spring	erythematous, confluent, maculopapular rash, starting at the hairline and descending	Koplik spot, high fever, 3 C's of cough, coryza, and conjunctivitis, and Forchheimer spots
scarlet fever	fall to spring	generalized erythematous rash with sandpaper texture, starting on the face and upper trunk, and descending	Pastia lines, Forchheimer spots, strawberry tongue, exudative pharyngitis, abdominal pain, rheumatic fever
rubella	late winter and early spring	rose-pink, maculopapular rash, descending	lymphadenopathy, arthralgias, Forchheimer spots
parvovirus B19	winter and spring	slapped cheek rash on face and lacy reticular rash on extremities	rash waxes and wanes over weeks, arthritis, aplastic crisis
roseola	spring	rose-pink, maculopapular rash on the neck and trunk	lymphadenopathy, febrile seizures, Nagayama spots
varicella	late winter and early spring	vesicles on an erythematous base with crusting, starting on the face and trunk and spreading outwards	pruritis
hand-foot-mouth disease	late summer or early fall	elliptical vesicles on an erythematous base, involving oral mucosa and palms and soles	vesicles on hands and feet and inside the mouth

Numbered Childhood Exanthems

1. First disease: measles
2. Second disease: scarlet fever, caused by group A Streptococcus
3. Third disease: rubella or German measles
4. Fourth disease: "Duke's disease"; may or may not exist; possibly staphylococcal scalded skin syndrome
5. Fifth disease: erythema infectiosum, caused by parvovirus B19
6. Sixth disease: roseola infantum, caused by human herpesvirus 6 or 7

Further Reading

• First to seventh diseases: discarded diagnoses? BMJ. 2015;351:h3525.