Comparative Statistical Analyses of the 1916 and 1931 Epidemics of Poliomyelitis in and About the City of New Haven *

In the following report we have assembled and compiled some rather conventional statistical data gleaned from two extensive epidemics of poliomyelitis which have occurred in and about the City of New Haven. Our interest lies mainly in analyzing certain events which occurred within this area during both epidemics, and comparing them. Such events, which lend themselves for comparison indude: (a) the time of onset and decline of the two epidemics; (b) the age distribution of the populations attacked; (c) the geographical location (home sites) of cases in each epidemic. It should be stated, at once, that present methods of reporting the incidence of poliomyelitis are inadequate because we still do not know the clinical limits of this disease. In particular, the problem of so-called "abortive" forms of the disease has been a knotty one, since Wickman"0 first called attention to their existence, for the symptomatology of these "abortive" forms is indefinite, including as it does, many examples of illness which seem to be merely a gastrointestinal upset, or a mild bout of fever, headache, vomiting, etc. Consequently, most physicians find it very difficult to make a diagnosis of either poliomyelitis or "abortive" poliomyelitis, except in the presence of tangible signs of the disease, such as evidences of meningitic or myelitic involvement. In any event, the question of uncertainty of diagnosis has excluded cases without meningitic or myelitic involvement from statistics on poliomyelitis5 7, although it is needless to point out that, if the disease is thus limited, such a concept will enormously influence views not only on the epidemiology, but also on the fundamental nature of this disease. This problem was vividly impressed upon us during the recent (1931) epidemic. For practical purposes some diagnostic criteria were necessary and these gradually resolved themselves into: (a) the development of paralysis in association with the usual signs of