Abortive Poliomyelitis. ∗

Abstract

We have shown a high rate of immunity to poliomyelitis in the general population, 1 and the distribution of this immunity is correlated with the incidence of the disease not only in the different ages but with concentration of population. The vast majority of urban adults were found to be immune and the incidence of immunity decreased rapidly and was lowest in the youngest age groups where the incidence of the disease is highest. We found the same type of curve to obtain in rural communities although there was considerably less immunity present. On comparing our findings with similar findings in diphtheria we found a very close parallelism between the two diseases.

It has become important to determine the mechanism by which this general immunization takes place. Since Wickmann's first suggestion of the probable occurrence of abortive forms of the disease the impression has become general that much, if not all, of this immunity is accomplished through abortive attacks of the disease.

During rather intensive studies in Massachusetts and Vermont over a period of years, we have not been convinced that there are any large numbers of such mild illnesses concurrent with an outbreak of the frank disease. A favorable opportunity to determine the incidence of such abortive forms at the time of an outbreak came to us in October, 1930, when 5 frank cases of poliomyelitis occurred in the town of Bedford, Mass., (population 1700) some 20 miles from Boston. With the appearance of the first case, residence was established in the town, and a house to house canvass made over a period of 6 weeks, and histories of all illnesses within 2 weeks previous to the appearance of the first case were collected. School was in session at the time and all of those stricken with the disease were pupils of the local school.