Over the past decades, the good health and exceptional longevity of the Japanese have achieved an almost mythical status. Rightly so: on average, Japanese people live longer, remain slimmer, and suffer less breast, prostate and other cancers than people in other developed countries. And it is not only the elderly and middle-aged that profit; infant mortality is likewise the lowest in the world. This is very fortunate for the Japanese of course, and could not have escaped the attention of the world's health scientists. Over the past decades, much research has been done into the Japanese' lifestyle and diet, looking for the causes of their remarkable fitness. The country has also gained a striking popularity on the lunatic fringes of healthcare; short of awful taste, nothing appears to sell a health product or food supplement as well as the claim that it is traditionally Japanese. This is remarkable, for although the good health of the Japanese is certainly real, it is not at all traditional. Up to about 1950 the vast majority of the Japanese never enjoyed good health, but suffered through short, sick lives, plagued by rampant infectious disease and shockingly high infant and childhood mortality. In terms of health Japan lagged well behind similarly developed European countries. The millions of elderly Japanese who nowadays have come to symbolize their country's good health were born in an era when it would have compared favorably to only the very poorest of modern sub-Saharan African countries.
The bad health of the prewar Japanese had many causes, and the range of medical problems that affected them was enormous. But one disease, tuberculosis (TB), stood out as a particularly virulent, lethal scourge, and was by far the leading cause of death in the country during the first half of the century. Few, if any, industrializing countries at the time had failed as dismally as Japan to curb the disease. During the Asia-pacific war the situation escalated, and when Japan surrendered to the allies in August 1945 the disease was rampant, claiming uncounted numbers of lives, and instilling fear in the Japanese. Not in them alone, moreover; the newly installed General Headquarters (GHQ) under general MacArthur recognized that TB was a threat to allied personnel, as well as to the success of the occupation, and supported efforts to control the disease. These efforts were, superficially judged, much more effective than those of successive Japanese governments before 1945 had been, a fact the Americans were eager to emphasize. By the time effective chemotherapy became widely available in Japan in the 1950s, the number of registered deaths caused by the disease was already less than half the prewar level and new infections among the country's youth had been decimated. It is difficult to say, however, to what extent policies introduced by either GHQ or the postwar Japanese governments actually caused this spectacular decline. If they managed to cure TB, they themselves had little idea how they had done so.
"A Healthy Defeat? Mapping the Postwar Decline of Tuberculosis in Japan, 1945-1955." In Virus: Beiträge zur Sozialgeschichte der Medizin 4 no.1 (2010).