The virus exanthema subitum (human herpesvirus 6 HHV-6, Human herpes reseovirus 9) exists in two variants, HHV-6A and HHV-6B, differing somewhat genetically, biologically and antigenically. The primary infection of HHV-6 frequently occurs as a vague illness with a fairly high fever, sometimes accompanied by convulsions. In older infants and toddlers up to one-fifth of the fever is of a roseolovirus origin. A rash appears in only about 20% of children, that is exanthema subitum or roseola infantum, also known as the sixth exanthematic illnesss. Hepatitis or atypical lymphocytosis are rarely present . If a reactivation has been reported, and in otherwise normal people (pregnancy after admission to the intensive care unit for other serious diseases) presented without symptoms. The reactivation of HHV-6B, however, occurs in up to half of transplant recipients. It presents again as a febrile illness, but also encephalitis, pneumonia, hepatitis and symptoms of bone marrow suppression and deterioration of a CMV infection. Strikingly there are also mental status changes - from confusion to even coma. HHV-6 also contributes to immune suppression caused by HIV co-infection and induces the production of cytokines.
Amplification and detection of the viral genome by means of nested PCR (minimum sensitivity 5 copies per reaction) and reverse hybridization (minimum sensitivity 5 copies per reaction)
- whole blood (EDTA tube - transport to the laboratory within 24 hours from extracting it in room temperature)
- plasma (after centrifugation of whole blood in EDTA tube at 1200xg for 10 min. to 7 days may be stored at 2/8 °C, longer at -18 / -22 °C)
- cerebrospinal fluid, urine, biopsy (-18 / -22 °C)
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