Serology Versus Clinical Signs or Symptoms and Main Laboratory Findings in the Diagnosis of Exanthema Subitum (Roseola Infantum)

Twenty-five patients with clinical exanthema subitum (roseola infantum) were enrolled into a study, where acute-phase and convalescent sera were examined for antibodies to human herpesvirus 6 (HHV-6), several other viruses, and other microbes. In addition, an acute-phase fecal specimen was examined for viruses by electron microscopy. Confirmative or suggestive serologic evidence for recent HHV-6 infection was obtained in 23 (92%) cases. Conversion to HHV-6 was found in 19 (76%), a diagnostic (greater than or equal to 4-fold) titer rise in 2, a twofold titer rise in 1, and a stable relatively high titer in 1 of the patients; only 2 (8%) individuals remained negative. The other microbial assays produced only two slight mycoplasma antibody rises and one rotavirus identification in the fecal specimen. It is concluded that if the clinical diagnosis of exanthema subitum is deemed doubtful, HHV-6 infection is verifiable in about 75% of the cases by serology.