Eight cases of acute human herpesvirus type 6 (HHV6)
infection in infants were diagnosed serologically by the demonstration of
IgM anti-HHV6 (8/8) and a significant change in total anti-HHV6 antibody titre (6/8). Four infants were sufficiently ill to require admission to hospital and further investigations: one with
encephalitis and three with gross hepatosplenomegaly, two of whom had evidence of simultaneous
infection with another herpes-virus. The remaining four infants had an illness compatible with
roseola infantum, although this diagnosis had not been made clinically. Sera from two of those infants with
rash had been sent for analysis to exclude
rubella because the infants' mothers were pregnant. The other two had received
antibiotics when febrile, and the subsequent appearance of the roseola
rash had raised the possibility of
antibiotic allergy. The data suggest that there are clinical syndromes in addition to
roseola infantum associated with the presence of
IgM anti-HHV6, in which serological screening for evidence of acute HHV6
infection may be useful.