Herpesvirus 6 - HHV6

Herpesvirus 6 - HHV6

 

Human herpesvirus 6 (HHV6), a member of the ß-herpesvirus subfamily, exists as 2 closely related variants, HHV6 A and HHV6 B.

Epidemiology

  • Incidence – most children >2 years are seropositive
  • Transmission
    • Oral droplets
    • Transfusion
    • Organ transplantation

Organism

  • DNA virus
  • Isolated in 1986 from patients with AIDS and lymphoproliferative disease, the virus was originally named human B-lymphotropic virus (HBLV)
  • Following the primary infection, the virus establishes a latent infection in lymphocytes and monocytes and may persist in various tissues with a low-level of replication

Clinical Presentation

  • Primary infection with HHV6 produces a fever that may exceed 40°C, persisting for 3-5 days
  • Primary infections in children often result in a fever followed by development of exanthem subitum, known as roseola infantum or sixth disease
    • Rash develops on trunk and spreads to extremities
  • Primary infections in adults, though rare, may involve:
    • Infectious mononucleosis-like disease
    • Fulminant hepatitis
    • Atypical lymphocytosis
  • Associated complications may include:
    • Meningitis
    • Meningoencephalitis
    • Fulminant or chronic hepatitis
  • Evidence suggests HHV6 may act as an opportunistic agent in:
    • Immunodeficient patients undergoing bone marrow or organ transplants
    • HIV-infected individuals by means of primary infection reactivation of a latent infection or a persistent infection
    • In immunocompromised or immunosuppressed patients
    • Symptoms -- Fever, skin rash, organ disease or rejection, encephalitis, encephalopathy, pneumonitis, hepatitis, bone marrow suppression and death

Diagnosis

  • Laboratory testing
    • PCR

Differential Diagnosis

  • Measles
  • Rubella
  • Viral/bacterial meningitis
  • Viral illness
  • Seizure disorder

See Also