Fifth disease

Anderson and colleagues identified B19 as the cause of erythema infectiosum or fifth disease in 1983. The incubation period for erythema infectiosum ranges from 4 to 28 days (average, 16–17 days). The prodromal phase is mild and consists of low-grade fever, headache, and symptoms of mild upper respiratory tract infection. The hallmark of erythema infectiosum is the characteristic rash, which occurs in three stages that are not always distinguishable. The initial stage is an erythematous facial flushing, often described as a “slapped-cheek” appearance. The rash spreads rapidly or concurrently to the trunk and proximal extremities as a diffuse macular erythema in the second stage. Affected children are afebrile and not ill-appearing.