Etiology of measles- and rubella-like illnesses in measles, mumps, and rubella-vaccinated children

The viral etiology of measles- or rubella-like illnesses after MMR (measles , mumps, and rubella) vaccination was studied prospectively in 993 acutely ill Finnish children with fever and rash in 1983-1995. Their sera were test ed for adeno-, entero-, and parvovirus B19 antibodies. Sera of 300 children <4 years old were also tested for human herpesvirus 6 (HHV-6) antibodies. Measles and rubella had been excluded by previous antibody testing. Serolog ic diagnosis of adeno-, entero-, or parvovirus infection was based on EIA ( IgM or IgG antibodies) and that of HHV-6 on indirect immunofluorescence. A viral etiology was verified in 368 cases, most commonly parvovirus (20%), f ollowed by enterovirus (9%) and adenovirus (4%). Among young children, HHV- 6 infection was found in 37 (12%), Thirty-eight children (4%) had double in fections. This study confirms that measles- or rubella-like illnesses in MM R-vaccinated children are often caused by other viruses. Each suspected vac cine failure requires laboratory confirmation to maintain reliable surveill ance and control and to establish the specific etiology of the disease.