Introduction to Herpesvirus 6 Infection

Like other herpesviruses, human herpesvirus 6 causes an initial infection, a life-long latency, and a clinical reactivation, especially in hosts who are immunocompromised

Pathophysiology
The infectious agent in roseola infantum/exanthem subitum was demonstrated to be present in blood by inoculating healthy infants with serum from ill infants, a procedure considered very dangerous by today’s standards.

Clinical Presentation

• Human herpesvirus 6 (HHV-6) is the single most common cause of hospital visits in infants with fever.
• Roseola is characterized by an initial febrile phase of 3-5 days, with temperatures reaching 40°C.
• With the fever, some children exhibit bilateral periorbital edema in the prodrome.
• At or near the period of defervescence, a maculopapular rash is observed on the infant’s trunk and neck; however, this rash is found in the minority of patients (10%).
• Children can contract primary human herpesvirus 6 without manifesting a rash.
• Human herpesvirus 6 can be isolated from the blood for the first 5 days and later is found intermittently or persistently in saliva, stool, and, rarely, urine.

Physical Examination

• High-grade fever higher than 39.5°C (103°F) persists for 3-5 days and then resolves abruptly.
• Rash appears after 12-24 hours of resolution of fever. In many incidents of human herpesvirus 6, rash appears during defervescence or within a few hours.
• Rash of roseola is erythematous, nonpruritic, mildly elevated, and consists of rose pink papules (roseola meaning pink-colored rash). The rash blanches on pressure and mainly is distributed on the trunk, arms, and neck.
• The rash fades in 1-2 days.
• Most children are playful despite high-grade fever; however, anorexia, irritability, and listlessness may be the presenting signs.

Laboratory studies

Laboratory diagnosis is rarely required in patients who are immunocompetent because of the self-limiting nature of primary human herpesvirus 6 (HHV-6) infection.

Leukopenia with lymphocytosis may suggest the diagnosis.

Transaminase elevations, cholestasis, and thrombocytopenia were noted.

Obtain serology. Four-fold increase in human herpesvirus 6 immunoglobulin G (IgG) antibodies in serum suggests active human herpesvirus 6 infection (primary or reactivated).

Management

• Provide supportive therapy for patients with symptomatic human herpesvirus 6 (HHV-6) infection.
• Ensure adequate fluid balance.
• Administer acetaminophen or ibuprofen to patients with high-grade fever, patients who are uncomfortable, or patients who have a previous history of febrile seizures.