AN INDICATION AS TO IDENTITY BETWEEN THE INFECTIOUS DIARRHEA IN JAPAN AND THE AFEBRILE INFECTIOUS NONBACTERIAL GASTROENTERITIS BY HUMAN VOLUNTEER EXPERIMENTS

From the end of the year 1947 to the early summer of 1948, a diarrheal disease of infectious nature prevailed in Japan. The disease appeared fairly abruptly and when it was recognized as a serious public health problem, it had already been spread almost all over Japan. It stimulated research workers as well as public health officers as a hitherto unknown disease entity. Human volunteer experiments conducted by some Japanese workers (Kojima et al., 1948; Yamamoto et al., 1948) revealed that the etiological agent of the disease was filtrable. The disease was called infectious diarrhea by Kojima et al. (1948) . It was reported by Gordon, Ingraham and Korns (1947) that a diarrheal disease whose clinical features seemed to be almost the same as those of the disease in Japan, draw attention frequently in the form of institutional outbreaks, but sometimes attacked families in localized areas mostly in 1946 and 1947 (see also Ingalls and Britten, 1951; Britten, Rubenstein, Raskin and Strassmann, 1951; Smillie, Howitt and Denison, 1948) . The disease was at first named epidemic gastroenteritis by Gordon, Ingraham and Korns, but later afebrile infectious nonbacterial gastroenteritis in order to distinguish from the other form of diarrheal disorder, namely febrile infectious nonbacterial gastroenteritis (Gordon, 1954; Jordan, Gordon and Dorrance, 1953; Gordon, Meneely, Currie and Chicoine, 1953) . The afebrile infectious nonbacterial gastroenteritis seems to be still continuing to occur from time to time in several places in the United States, according to Gordon (1954) and Gordon, Ingraham, Korns and Trussell (1949) . The situation appears to be the same for the infectious diarrhea in Japan, because it is reported that several localized occurrences of this disease were found each year thereafter (Fukumi, Ishimaru and Yamaguchi, 1948; Ishimaru, 1950; Kojima, Fukumi and Ishimaru, 1953), some of which were identified as such by human volunteer experiments (Fukumi, 1955; Hirayama, Fukumi, Nakaya, Kusano, Aoyama, Kagawa, Noguchi and Murate, 1955; Ishimaru, Koike, Amamiya, Hagihara, Fukumi and Nakaya, 1955) . There is no positive evidence of the existence of this disease in Japan before or during the Second World War, and from several epidemiological points of view, it may be reasonable to consider that the infectious diarrhea in Japan and the of ebrile infectious nonbacterial gastroenteritis in the United States are an identical disease and that its occurrence in Japan h