A brief description of one of the most common viruses affecting children. The presentation describes the disease, its onset, clinical features, signs and symptoms and treatment. Helpful for doctors, dermatologist, child specialists, nurses and medical students preparing for exams.

1. Viral Exanthem Part II:
Roseola infantum:

2. Definition and nomenclature:
 Roseola infantum is an acute febrile illness with a maculopapular eruption.
 The classic presentation of roseola infantum is a 9- to 12-month-old infant who acutely develops a high
fever and often a febrile seizure. After 3 days there is a rapid decline in fever, and a morbilliform rash
appears.
 Also called:
 Exanthema subitum or
 Exanthem subitum
 Sixth Disease
 3 day fever

3. Epidemiology:
Incidence and prevalence:
 Roseola infantum is the most common exanthematic fever in children under the age of 2 years
 Incidence: 24% of acute febrile illness presenting at a paediatric emergency department.
Age
 Peak incidence is between 6 and 9 months.

4. Pathophysiology:
 Causative organisms
 HHV‐6 (most commonly)
 HHV‐7
 Roseola is spread as air borne or droplet infection.
 The child is probably infectious during the whole period of the disease and may be even before the high
temperature begins.

5. Clinical features:
History
 The incubation period is from 10 to 15 days.
Presentation:
 Early Symptoms:
 The first sign of illness is abrupt onset of fever, usually 39.5 - 40°C, which persists for 3–5 days ; Accompanied by few
or no symptoms.
 Irritability,
 Inflamed tympanic membranes,
 Papules and ulcers at the posterior palate and uvula (Nagayama spots)
 Periorbital oedema and
 Haematuria
 Exanthem:
 As the temperature falls, an eruption of discrete rose‐pink maculopapules develops on the neck and trunk;
 May spread to the arms, face and legs.
 The lesions may have surrounding pallor and rarely become vesicular.
 Lasts for 2 days
 Patient’s cervical and occipital lymph nodes are usually enlarged.

6. Clinical variants:
Primary infection in Adults:
 There may be a mononucleosis‐like illness, with variable fever or rash and with mainly cervical
lymphadenopathy, which may persist for up to 3 months;
 or an acute but self‐limiting hepatitis

7. Differential diagnosis:
 Measles:
 Lack of upper respiratory tract symptoms.
 Rubella:
 Usually seen in older children
 Scarlet Fever
 Exanthematous drug reaction

8. Complications and co‐morbidities
 Febrile convulsions: occur in 13% of the cases.
 Fatal encephalitis:
 Thrombocytopenia
 Purpura fulminans
 Haemophagocytic syndrome
Associations:
 Papular purpuric gloves and socks syndrome
 Gianotti–Crosti syndrome
 Stevens–Johnson syndrome
 Pityriasis rosea

9. Disease course and prognosis:
 Rash fades after 1-2 days leaving no scaling or pigmentation.
 Reactivation of the latent virus may occur, especially in immune suppression

10. Investigations:
(1) Serology:
 Confirmation is by demonstrating a seroconversion or rise in antibody titre to HHV‐6, by indirect
immunofluorescence using cells infected with HHV‐6 as antigen.
 IgM antibody appears 5–7 days after the rash, reaching maximum titre after 2 weeks and persisting for
about 2 months.
 Does not distinguish between HHV- 6A and 6B strains
(2) PCR:
 Molecular detection of viral RNA by RT‐PCR or DNA by PCR
 Distinguishes HHV‐6A from ‐6B
 HHV‐6 DNA has been demonstrated in the cerebrospinal fluid of children with both primary HHV‐6
infection and also at times of recurrent seizures following exanthem subitum,
(3) Complete Blood Count:
 During the first 2 days there may be leukocytosis
 As the rash develops, leukopenia with a relative lymphopenia

11. Management:
First line
 Only symptomatic measures are usually required.
Second line
 Antiviral therapy with ganciclovir, valganciclovir, cidofovir or foscarnet would be appropriate in
individuals with severe disease.

12. Roseola Infantum
Timeline:
Fever:
Lasts
3-5 days
Maculopapular Rash
Appears as fever settles.
Lasts 2 – 3 days
IgM antibodies appear reaching
peak titres in 2 weeks. Persisting for
2 months
Incubation Period:
10-15 days
5-7 days
later

13. Summary Of Viral Agents and their
Clinical Manifestations:

14. Future Topics to be Discussed:
1)Rubella
2)Infectious Mononucleosis
3)Adenovirus
4)Enterovirus
5)Cytomegalovirus
6)West Nile Fever