Medicine: The Disease Year

The one thing certain about each year's polio epidemic is its uncertainty. The disease may spread with a rush early in the summer, reach a peak by mid-August (as in 1953's severe season) and then recede. Or it may come from behind and keep racing ahead into late September—as happened in 1952, one of the two worst polio years in U.S. history. Then, too, the disease usually plays hopscotch across the map. One year it will be most prevalent in the northern Midwest, only to hit the Northeast or the Pacific Coast with special force the next. Polio may be concentrated in big cities as was the case in 1916's epidemic (the other contender for all-time worst); or else an equally large total number of cases may be spread over the corn counties.

The 1955 polio season made history by its unique sendoff: the statisticians had scarcely begun feeding figures into their machines for the new disease year, beginning in April, when the Cutter vaccine incident broke, and it became clear that some of the Salk vaccine contained live virus. Almost at once the nation's total of polio cases hit an alltime high for the date (147 in the last week of April), and kept on doing so for six straight weeks. The cases among the children inoculated with Salk vaccine (mostly by Cutter) and among their contacts (a total of 422) were enough to explain this.

Last week the polio season was back on the track—as much as it ever is. Cases for the disease year totaled 4,500, fewer than in any year since 1951. This was encouraging, but Public Health Service experts would make no prediction on the basis of such preliminary data of how the disease year as a whole might turn out. One thing was sure: the Salk vaccination program, which had covered about 4% of the nation's population (among whom 10% of polio cases might be expected), had not gone far enough to have a major effect on overall figures. Only careful, detailed study will show the statisticians later on whether it has had a substantial effect among first-and second-graders.

A striking feature of this year's polio picture was its geography. For five years New England had enjoyed relative immunity from the abnormally heavy outbreaks plaguing the rest of the country. But last week Massachusetts (and especially Suffolk County, which includes Boston) was hard hit. with 146 cases, compared with 52 the week before and twelve a year ago. There was a similar sharp rise in Milwaukee. P.H.S. officials were watching these increases most anxiously, fearing the possibility that 1955's epidemic, still as unpredictable as a hurricane far at sea, might hit the big cities of the Northeast.