Roseolovirus

Roseolovirus is a genus within the family Herpesviridae, subfamily Betaherpesvirinae, and includes three human pathogens: human herpesvirus 6A (HHV-6A), human herpesvirus 6B (HHV-6B), and human herpesvirus 7 (HHV-7). These viruses have large double-stranded DNA genomes and establish latent infections in human cells, primarily CD4+ T lymphocytes, with potential reactivation during immunosuppression.

Epidemiology and transmission: Most children become infected in early childhood; by age 2, seroprevalence is high. Transmission is mainly via saliva. Primary infections are often asymptomatic or result in mild febrile illness; HHV-6B is classically associated with roseola infantum, or exanthem subitum, a feverish illness of infancy that can be followed by a rash. HHV-7 can cause similar presentations but is less consistently implicated.

Clinical features: In healthy children, infection is usually self-limited and mild. In immunocompromised individuals, including transplant recipients and people with HIV, reactivation can cause fever, lymphadenopathy, pneumonitis, encephalitis, or retinitis. CNS involvement is a recognized complication in the context of reactivation or primary infection.

Diagnosis and treatment: Diagnosis relies on detection of viral DNA by PCR in blood, CSF, or respiratory samples; serology has limited utility for acute diagnosis. There is no licensed vaccine. Most primary infections require no specific therapy, but severe or progressive disease in immunocompromised patients may be treated with antiviral agents such as ganciclovir, foscarnet, or cidofovir, with variable responses. Prevention focuses on infection control and careful management of immunosuppression.