Simultaneous infection with human herpesvirus‐6 and measles virus in infants

Two infants (4 and 5 months of age) with a febrile episode for 3 and 5 days, respectively, developed skin rashes after the fever subsided and were diagnosed as exanthem subitum. The rash continued for 5 days followed by mild‐to‐moderate pigmentation. Human herpesvirus‐6 and measles virus, which were confirmed by a specific immunofluorescence assay and by electron microscopy, were isolated simultaneously from blood in the acute stage of the disease but not from the convalescent stage. The titer of the herpesvirus‐6 in blood was greater then that of measels. Specific serologic assays showed marked seroconversion against human herpesvirus‐6 but not to measles virus. The results suggest that dual infection with human herpesvirus‐6 and measles virus results in atypical exanthem subitum or modified measels with unique immunologic responses.