Viral infection in a child: Roseola infantum (HHV 6) Flashcards
Define roseola infantum (HHV 6).
Roseola is a common childhood disease. The cause is primary infection with human herpesvirus 6 (HHV-6).
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, a rapid defervescence occurs, and a morbilliform rash appears.
Explain the aetiology/risk factors of roseola infantum (HHV 6).
The Roseolovirus genus of the beta herpes virus hominis subfamily contains human herpesvirus (HHV)–6 and HHV-7. HHV-6 has 2 variants: HHV-6A and HHV-6B. Their major differences are cellular tropism.
HHV-6B is the cause of roseola in infants. Because seropositivity is nearly 100% in older children, most primary infections with HHV-6B are asymptomatic.
Summarise the epidemiology of roseola infantum (HHV 6).
human herpesvirus 6 (HHV-6) infection is nearly universal. In emergency clinics, HHV-6 has been reported to be responsible for 10-45% of cases of febrile illness in infants.
What are the presenting symptoms of roseola infantum (HHV 6)?
The classic roseola infantum patient is a 9- to 12-month-old infant in previously good health and who has an abrupt onset of high fever (40°C), which lasts for 3 days with nonspecific complaints. A febrile seizure occurs in 15% of patients. Rapid defervescence is striking with the onset of a mild, pink, morbilliform exanthem.
In roseola infantum patients who are immunocompromised, the onset of symptoms is usually abrupt, with fever, malaise, and CNS and other organ system involvement.
What are the signs of roseola infantum (HHV 6)?
Few clinical findings are observed early in the course of roseola infantum. Lack of URTI is notable, and meningeal signs and encephalopathy are not present. GI symptoms, sings of electrolyte imbalance, or evidence of dehydration are rarely present.
After an abrupt loss of fever, the characteristic rash appears. The eruption is generalized and subtle. It is composed of either discrete, small, pale pink papules or a blanchable, maculopapular exanthem that is 1-5 mm in diameter. This rash may last 2 days.
The characteristic enanthem (Nagayama spots) consists of erythematous papules on the mucosa of the soft palate and the base of the uvula. The enanthem may be present on the fourth day in two thirds of patients with roseola.
What are appropriate investigations for roseola infantum (HHV 6)?
FBC
Urinalysis
Blood cultures
CSF fluid examination
Antibody testing
What is the management of roseola infantum?
Supportive: Antipyretics and treatment of GI, respiratory, haematologic and CNS complications
What are complications associated with roseola infantum (HHV 6)?
In roseola infantum, complications are rare. Given that seroconversion is practically universal, finding any of the complications that have been reported in the gastrointestinal, central nervous, pulmonary, and hematopoietic systems is rare.
Children who have seizures with roseola are not expected to have further febrile or nonfebrile seizures.
What is the prognosis of roseola infantum (HHV 6)?
Practically all patients who are immunocompetent survive roseola infantum without sequelae.
In patients who are immunosuppressed, multisystem complications are not unusual. Infection may be chronic, leading to viral progression and death.
