Underestimation of the incidence of measles in a population of French children.

Data on titres of specific antibodies against measles virus and information given by families and physicians were analysed in 133 vaccinated and 117 unvaccinated children. Only 2 of the 133 vaccinated children reported a history of measles, while 131 had detectable levels of antibodies. Measles antibodies were detected in 102 (87.2%) of the unvaccinated children, but a history of measles diagnosed clinically by a physician was reported in only 42 of them. These findings suggest that subclinical cases of measles are possible and contribute to the high circulation of the measles virus in the child population in France.