Human Herpesvirus 6 (HHV‐6) Infection and Exanthem Subitum in Thailand

Abstract

Of SO patients in Thailand suspected clinically of having exanthem subiturn, 31 (62%) were serodiagnosed as HHV-6 infection. Sixteen strains of HHV-6 from 31 patients (52%) whose antibody titers had converted during convalescence were isolated during the acute phase. The disease occurred in infants from 3 months to 1 year of age and most frequently at age 4-6 months. Antibody only to HHVB converted in 23 of SO patients (46%), and seroconversion to HHV-6 and dengue virus was observed in 7 patients (14%), and to HHV-6 and Coxsackie B virus in 1 case (2%). In the 23 patients in whom seroconversion only to HHV-6 was observed, all had fever and rash which appeared after subsidence of the fever. Lymphadenopathy and relative lymphocytosis were recognized, associated with diarrhea, vomiting, running nose, cough and hepatomegaly. Febrile convulsions were seen in some cases. All patients recovered completely within a week.

Human herpesvirus 6.

“…The highest titers of IgM are seen at 2 to 3 weeks after infection, and IgM is usually undetectable by 2 months postinfection (484). Anti-HHV-6 IgG usually appears within 7 to 10 days after fever has subsided (41,519), increases in avidity over time (531), and remains at measurable levels for many years. HHV-6-specific IgA titers were elevated in the limited number of patients with advanced oral carcinoma examined (548).…”

“…Concurrent infections of HHV-6 with other human pathogens including measles virus, HCMV, HSV-1, EBV, dengue virus, adenovirus, coxsackie B virus, parvovirus B19, L. pneumophila, P. carinii, and possibly HHV-7 have been reported (41,102,238,286,412,442,487). Whether these concurrent infections with HHV-6 are specifically associated with an immunosuppressive effect or are coincidental has not been determined.…”

Lymphoproliferative Syndromes Associated With Human Herpesvirus-6a and Human Herpesvirus-6b

“…Thrombocytopenia, neutropenia, and leukopenia are commonly found as well. 73 Notably, reactive “atypical” lymphocytes and hemophagocytosis may be observed in bone marrow, 74 , 75 and a mononucleosis-like illness, with reactive lymphocytosis and liver dysfunction, has been described. 76 Two unique cases documenting HHV-6 infection with unusual lymphoproliferation in very young children have been reported: One infant, 7 months old, died suddenly after developing otitis media, and HHV-6 was found by PCR in tissue samples and in atypical lymphoid infiltrate via ISH.…”