Measles: summary of worldwide impact.

Nearly every measles infection results in well-recognized clinical disease. In nonimmunized populations almost every child will get measles early in life. The universality of the disease in nonimmunized communities, particularly those in the developing world, has led to a more or less passive acceptance of measles as an unavoidable risk of early life. The clinical spectrum of measles ranges from a mild, self-limiting illness to a fatal disease. Conditions encountered mainly in the developing world, e.g., unfavorable nutrition, high risk of concurrent infection, and inadequate case management -- particularly at home -- favor the development of complications and adverse outcome. Conversely, good clinical management of an otherwise healthy child, a situation seen mostly in the developed world, greatly influences the course of the disease. Hence many in the medical profession believe that measles is a mild disease except among populations living under particularly unfavorable conditions. Measles vaccine is effective in preventing disease in the individual and in controlling it in the community if it is given at the critical age when maternal antibodies wane and the risk of natural infection increases sharply and if a high immunization rate is maintained in the target population. The experience with immunization, particularly in sub-saharan Africa, is rewarding: mothers who had previously accepted measles as an unavoidable risk clamour for immunization of their children once its effectiveness has been demonstrated. No reason exists for measles to claim its present toll of morbidity and mortality. With extension of the Expanded Programme on Immunization of the World Health Organization, the impact of measles should progressively decline.