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New Treatments for Roseola

Major clinical manifestations of roseola and infection with human herpesvirus (HHV) 6 are variable in children younger than 3 years of age. These manifestations include roseola (exanthem subitum, sixth disease) in approximately 20% of children, undifferentiated febrile illness without rash or localizing signs, and other acute febrile illnesses, often accompanied by cervical and postoccipital lymphadenopathy, gastrointestinal or respiratory tract signs, and inflamed tympanic membranes. Fever is characteristically high (>39.5°C [103.0°F]) and persists for 3 to 7 days.

Seizures, which result in emergency department visits, occur during the febrile period in approximately 10% to 15%. The virus persists and may reactivate. The clinical circumstances and manifestations of reactivation in healthy persons are unclear. Illness associated with reactivation has been described primarily in immunosuppressed hosts in association with manifestations such as fever, hepatitis, bone marrow suppression, pneumonia, and encephalitis. Recognition of the varied clinical manifestations of HHV-7 infection is evolving. Many, if not most, primary infections with HHV-7 may be asymptomatic or mild; some may present as typical roseola and may account for second or recurrent cases of roseola.

Human herpesvirus 6 and HHV-7 are members of the family Herpesviridae, which contains a large, double-stranded, DNA genome. Strains of HHV-6 belong to 1 of 2 major groups.

Humans are the only known natural hosts for HHV-6 and HHV-7. Transmission of HHV-6 to an infant most likely occurs via the asymptomatic shedding of persistent virus in secretions of a family member, caregiver, or other close contact. During the febrile phase of primary infection, HHV-6 can be isolated from peripheral blood lymphocytes in which the virus may persist subsequently, as well as from other sites, including saliva and cerebrospinal fluid. The attack rate is highest in children between the ages of 6 and 24 months. Infection within the first few months of age also occurs but is relatively uncommon before 3 months or after 3 years of age. Virus-specific maternal antibody is present uniformly in the serum of infants at birth .

Like HHV-6, HHV-7 is a ubiquitous agent, with infection occurring during early childhood, usually after HHV-6 infection. Lifelong persistent infection is established, and HHV-7 DNA may be detected in cerebrospinal fluid, cervical secretions, and saliva, with infectious virus present in more than three fourths of saliva specimens obtained from healthy adults. Like HHV-6, HHV-7 transmission to young children is likely to occur from contact with infected respiratory tract secretions of healthy persons.

The diagnosis of primary HHV-6 infection currently necessitates use of research techniques to isolate the virus from peripheral blood, as well as for demonstration of seroconversion. A 4-fold increase in serum antibody alone does not necessarily indicate new infection.

Diagnostic tests for HHV-7 are limited to research laboratories, and reliable differentiation between primary infection and reactivated is problematic. Serodiagnosis of HHV-7 is confounded by serologic cross-reactivity with HHV-6 and by the potential ability of HHV-6 to be reactivated by HHV-7 and possibly other infections.

Treatment:

Supportive. For immunocompromised patients with serious HHV-6 disease, some experts recommend a course of ganciclovir.