Rubella--world impact.

Worldwide, rubella is considered a public health problem because of the risk of infection to the fetus and of subsequent congenital defects. It is not a notifiable disease in most countries, and even where it is, it is underreported, and greater than 50% of infections are clinically inapparent. The impact of rubella is therefore gauged mainly through seroepidemiologic studies. Rubella appears to be endemic worldwide except in some remote areas or islands, where explosive outbreaks may occur. In general, a large proportion of a population is infected before puberty, but approximately 20% of adults may remain susceptible. Effective vaccines against congenital rubella exist, and many countries have already begun or are considering initiating large-scale immunization programs. In the developing world, where problems compete for priority in the mobilization of meager available resources, certain factors need to be considered before such programs are launched, including the ability to effectively deliver a program, the relationship between susceptibility and the age-fertility pattern, the incidence of congenital rubella, and the cost-effectiveness of intervention.