Clinical features of infants with primary human herpesvirus 6 infection (exanthem subitum, roseola infantum).

OBJECTIVE To clarify clinical features of patients with primary human herpesvirus 6 (HHV-6) infection (roseola infantum, exanthem subitum) in a large-scale study. SUBJECTS AND METHODS Clinical signs and symptoms were analyzed in 176 infants in whom exanthem subitum was initially suspected and primary HHV-6 infection was later confirmed. The infection was proved by isolation of the virus from blood, a significant increase in the neutralizing antibody titers to the virus, or both. RESULTS The primary HHV-6 infection, which occurred throughout the year, was observed in 94 boys and 82 girls (mean age, 7.3 months). Fever developed in 98% (mean maximum fever, 39.4 degrees C) and lasted for 4.1 days. Macular or papular rashes appeared in 98%, on face, trunk, or both, mostly at the time of subsidence of the fever, and lasted for 3.8 days. Other clinical manifestations occurred as follows: mild diarrhea in 68%, edematous eyelids in 30%, erythematous papules in the pharynx in 65%, cough in 50%, and mild cervical lymph node swelling in 31%. Twenty-six percent had bulging of the anterior fontanelle and 8% had convulsions. CONCLUSIONS Clinical features of patients with virologically confirmed exanthem subitum were comparable with those described before discovery of HHV-6.