Correlation of Infection Rate of Intestinal Helminths in Japanese Inhabiting Tropical Countries with Degree of Pollution of Drinking Water

Many Japanese inhabit tropical countries, and some of them are suffering from infectious diseases. In order to know the relationship between the prevalence of these diseases and the degree of faecal pollution of the drinking water, we have examined the drinking water in these countries of the world, and at the same time we have studied the infection rate of intestinal helminths of the Japanese who stayed 6 months or more in these countries. In total over 300 samples of drinking water from countries of South East and South West Asia, Middle East, East Africa and Central and South America were tested with potassium permanganate consumed test, and number of coliform bacilli from the drinking water was counted after cultivation. Relatively high proportion of samples appeared to be polluted by faecal matters. Then, we checked parasite eggs in the stool samples of Japanese who used the water samples in the tropical countries actually. Eggs of Ascaris lumbricoides, Trichuris trichiura, Taenia saginata and Clonorchis sinensis were found among the Japanese. Infection rate of intestinal helminths was proved to be highest among Japanese in Indonesia, and the rate was followed by those of people in South West Asia, in East Africa and in Central and South America. The relationship between the infection rate of intestinal helminths and the degree of pollution of the drinking water was studied. Significant relationship was observed between the infection rate of intestinal parasites of the Japanese inhabitants and the rate of water containing 102 or more/ml of coliform and of total micro-organisms (r=0.957). However, no relationship between the infection rate of Enterobius vermicularis among the Japanese children there and the degree of the pollution of drinking water was found.