La influenza es una enfermedad de de medio mi116n en Estados Unidos. En caracteristicas epidemiologicas muy partiChile, en el mismo periodo, se atribuyen a culares entre las cuales destaca su tendencia esta causa 36.115 defunciones. Estas cifras a producir grandes pandemias que se prodemuestran que el impacto producido por pagan a traves de paises y de continentes, la pandemia de influenza fue muy superior afectando en algunas oportunidades a una al de la guerra misma, afectando a la importante proporcion de la poblacion del humanidad no ~610 por sus graves tasas de

In view of the high mortality from measles in Chile, it was decided to undertake a double-blind, controlled trial of the Enders Edmonston B strain of live measles vaccine in that country as part of a WHO-sponsored programme to obtain information on reactions to that vaccine strain and on the antibody response elicited in children.Between July and December 1962, some 530 children 8 months to 3 years old received inoculations of vaccine, with or without gamma-globulin, or were given a placebo injection. The reactions were generally of moderate intensity and were not appreciably reduced in either frequency or intensity by gamma-globulin. Serological conversion was achieved in about 90% of the vaccinated.On the basis of this experience, it was decided to institute a large-scale immunization in Chile with the same vaccine; the campaign began in May 1963.

During the past 40 years the ecological approach to disease has become a basic concept of epidemiology. Among all diseases measles has stood as the classic example of successful parasitism. This self-limiting infection of short duration, moderate severity, and low fatality has maintained a remarkably stable biological balance over the centuries. Those epidemiologists, and there are many, who tend to revere the biological balance have long argued that the ecological equilibrium of measles is solidly based, that it cannot readily be disrupted, and that therefore we must learn to live with this parasite rather than hope to eradicate it. This speaker, not so long ago, was counted among this group and waxed eloquent on this subject in print. 1 Happily, this era is ending. New and potent tools that promise effective control of measles are at hand. If these tools are properly developed and wisely used, it should be possible