[1] Diagnosis is typically based on symptoms and does not need to be confirmed with blood tests (PCR or antigen).

[1] The disease may reactivate in those with a weakened immune system and may result in significant health problems.

[5] The rash is classically described as an erythematous morbilliform exanthem[4] and presents as a distribution of soft pink, discrete, and slightly raised lesions each with a 2-5mm diameter.

[8] Children with HHV-6 infection can also present with myringitis (inflammation of the tympanic membranes),[4] upper respiratory symptoms,[6][10] diarrhea, and a bulging fontanelle.

[6] In addition, children can experience pharyngitis with lymphoid hyperplasia seen on the soft palate and swelling of the eyelids.

[6][11] In rare cases, HHV-6 can become active in an adult previously infected during childhood and can show signs of mononucleosis.

[6] After exposure to roseola, the causative virus becomes latent in its host but is still present in saliva, skin, and lungs.

[6] HHV-6 is thought to be transmitted from previously exposed or infected adults to young children by shedding the virus through saliva.

[6] An exception is in people who are immunocompromised in whom serologic tests with viral identification can be used to confirm the diagnosis.

[8] Roseola should be differentiated from other similar-appearing illnesses, such as rubella, measles, fifth disease, scarlet fever, and drug reactions.

[6][8] In the case of febrile seizures, medical advice should be sought, and treatment aggressively pursued.

[5] If encephalitis occurs in immunocompromised children, ganciclovir or foscarnet have inconsistently shown usefulness in treatment.

[6] Many children exposed and infected can present without symptoms, which makes determining the incidence within the population difficult.

[5] John Zahorsky MD wrote extensively on this disease in the early 20th century, his first formal presentation was to the St Louis Pediatric Society in 1909 where he described 15 young children with the illness.

In this JAMA article, Zahorsky reports on 29 more children with roseola and notes that the only condition that should seriously be considered in the differential diagnosis is German measles (rubella) but notes that the fever of rubella only lasts a few hours whereas the prodromal fever of roseola lasts three to five days and disappears with the formation of a morbilliform rash.