Epidemiology and control of poliomyelitis

The Fifth International Conference on Poliomyelitis was held in Copenhagen, Denmark, from the 26th - 28th July 1960. Over a thousand delegates from 47 countries attended this conference. It might legitimately be asked why poliomyelitis alone among the virus diseases has acquired this honour and importance when some other diseases with greater morbidity and mortality rates have not been deemed worthy of this distinction. The answer lies in the fact that the changes in the pattern of this disease during the last hundred years have caused great anxiety and concern in the minds of epidemiologists and public health authorities all over the world. The relatively uncommon 'infantile paralysis' of the 19th century has become the epidemic poliomyelitis of the 20th century. Contrary to expectations and to the behaviour of most of the other intestinal infections, epidemics of poliomyelitis began to appear after the role of defective sanitation in the spread of enteric infections was recognised. Where the new ideas of sanitation were put into effect with much vigour, poliomyelitis epidemics became more frequent. Thus poliomyelitis presents itself as a threat in epidemic form to all countries which have and aspire to have improved standards of hygiene and living conditions unknown in the early part of the nineteenth century. Besides this change from an endemic to an epidemic pattern, the disease has evolved in another direction also. Over a hundred years ago, as the name 'infantile paralysis' suggests, poliomyelitis was mainly a disease of the lowest age group (under 5) in the community. But a shift, showing a significant incidence of the disease in higher age groups, with case -paralysis and case -mortality rates which are very much more pronounced than among the under -five group, has occurred. The inexorable tendency of notification figures to rise in almost every country presents the disease as a menace of world-wide significance.