Paralytic Poliomyelitis Before and After Mass Vaccination

Abstract

In many countries in Africa, Asia, and Central and South America, where pre ventive vaccination is far from universal, the incidence of poliomyelitis is rising, and large outbreaks are being reported.¹ In contrast, in the U. S. A., Canada, Australia, and New Zealand, the incidence has been falling steeply and progressively. In comparison with the years 1951-1955, the reduction by 1968 in these "developed" countries was 700-fold. The total number of reported cases in 1968 in all these countries together was only 62,1 and immunization cam paigns must be given the credit for reducing this morbidity and mortality.