Roseola overview

# Overview
Roseola is a disease of infants. It is characterized by an abrupt rise in body temperature to as high as 40C (104F) followed by a rapid drop to normal within the next 24 days which coincides with the appearance of an erythematous maculopapular skin rash that persists for 13 days. It is typically a benign disease which resolves without sequelae. Roseola disease is caused by Human herpes virus 6 (HHV6). HHV-6A and HHV-6B are two distinct species of HHV-6.

# Historical perspective
For the first time, Zahorsky of St. Louis in 1910 described a febrile exanthem occurring in infants which he termed roseola. Human herpes virus 6 was first identified in 1986.

# Classification
There is no established classification system for roseola.

# Pathophysiology
Roseola has two phases, the febrile and the rash (maculopapular) phase. During the first phase, HHV6 replicates in salivary glands and is secreted as primary source of infection. After complete resolution of the febrile phase, due to the latency of the virus in the lymphocytes and monocytes, the rash phase begins. A more serious form of HHV 6 is seen in older children, immunocompromised adults and organ transplant patients.

# Causes
Roseola is caused by Human herpes virus 6, a member of the Herpesvirales order, Herpesviridae family, Betaherpesvirinae subfamily, and Roseolovirus genus. Herpesviruses have a unique four-layered structure: a core containing the large, double-stranded DNA genome is enclosed by an icosapentahedral capsid which is composed of capsomers. The capsid is surrounded by an amorphous protein coat called the tegument. It is encased in a glycoprotein-bearing lipid bilayer envelope.

# Differential diagnosis
Roseola must be differentiated from other diseases that cause fever and rash, such as Rubella (german measles), Rubeola (measles), hand foot and mouth disease caused by coxsackie virus, erythema infectiosum caused by parvovirus B19, scarlet fever and even drug allergy.

# Epidemiology and demographics
There is no accurate data for the prevalence or incidence of roseola. This is because the disease is a self limiting disease and it is under reported in most cases. Roseola is an illness of young children, with a peak prevalence between 7 and 13 months. Ninety percent of cases occur in children younger than two years. Roseola occurs equally in boys and girls. It occurs throughout the year, although outbreaks may occur in groups according to season

# Risk factors
The common risk factors in the development of roseola includes infancy (younger 2 years), immunosuppression, and organ transplantation.

# Screening
According to the USPSTF, there is insufficient evidence to recommend routine screening for roseola.

# Natural history complications and prognosis
The symptoms of roseola usually starts in the first 2 years of life of an infant. If roseola, left untreated, it will resolve by itself. In rare cases, febrile seizures, encephalitis, aseptic meningitis, thrombocytopenic purpura, bone marrow failure and pneumonitis. The overall prognosis of roseola is very good.

# Diagnosis

## History and Symptoms
The hallmark of roseola is a non pruritic macular or maculopapular rash. A positive history of a high fever of 40oC (104oF) that lasts for 3 to 5 days.

## Physical Examination
Physical examination findings in a patient with roseola will depend on the presenting phase (febrile or rash). Vital signs are affected in the febrile phase and stabilize in the rash phase. Conversely, in the rash phase, vital signs become normal while skin appearance is affected.

## Laboratory Findings
The diagnosis of roseola is made clinically. However, in atypical cases, the diagnosis can be made by both serologic and direct detection of HHV6 virus in the saliva of the patient. Expected results of diagnostic studies include antigen detection, PCR, and immunofluorescence.

## Electrocardiogram
There are no electrocardiogram findings associated with roseola.

## Chest X Ray
There are no chest x ray findings associated with roseola.

## MRI
There are no MRI findings associated with roseola.

## Echocardiography or ultrasound
There are no echocardiography or ultrasound findings associated with roseola.

## Other imaging findings
There are no other imaging findings associated with roseola.

## Other diagnostic studies
There are no other diagnostic studies associated with roseola.

# Treatment

## Medical therapy
There is no treatment for roseola; it is a self limiting disease that resolves on its own without any medical intervention but antipyretics can be used as a supportive therapy in cases of high fever.

## Surgery
Surgical intervention is not recommended for the management of roseola.

## Primary prevention
There is no established method of prevention of roseola. However, standard sanitary procedures such as hand washing can help prevent the spread of the HHV 6 virus.

## Secondary prevention
There are no secondary preventive measures available for roseola.