This study was undertaken in order to elucidate the prevalences of the intestinal protozoan infection according to localities and the mode of the infestation in the mountainous area of Chollapuk-do, Korea during the year 1970-1971. 8,508 of fecal samples were collected among the inhabitants of the mountainous area, which covered 18 Myens(=Township) from 6 Guns(=County) in the eastern part of Chollapuk-do. Most of the inhabitants of this area were engaged in farming and living under lower economic and poor sanitary conditions. The samples were examined twice repeatedly by iodine stained direct fecal smear method. For the study on the mode of infestation, with the exception of drinking water, the zinc sulfate floatation technic was applied for the examinations of hog-feces, manure heap, garden soil, sewage, dishtowel, dust in room and floor, house fly and house rat. The results were summarized as follows: Among total 8,508 fecal specimens examined, 3,152(37.6 percent) were positive for the intestinal protozoa: E. histolytica 9.8 percent, E. coli 25.6 percent, E. nana 7.2 percent, G lamblia 6.8 percent, I. butschlii 0.6 percent, and C. mensnili 0.7 percent. A single infection of the intestinal protozoa was the highest(68.3 percent), and double infection(22.3 percent) triple, quadruple and quintuple infections were in decreasing order. The highest distribution (39.8 percent) was observed in the group aging 41-50, and the lowest (27.3 percent) in the group above 61. The groups under 10 years showed a relatively high positive rate among all age groups. Sexual distribution of protozoan infection showed slightly higher rate (38.6 percent) in male than that (35.4 percent) of female. Jangsoo-gun showed the highest positive rate (42.9 percent) and Namwon-gun was the lowest (32.5 percent). The prevalence of E. histolytica showed the highest (11.6 percent) in Imsil-gun and the lowest (6.9 percent) in Jangsoo-gun. E. histolytica cysts were found 9.1 percent among total 99 samples of hog feces, 4.8 percent among 78 samples of manure heap, 0.6 percent among 164 samples of fingernail dirt, 5.3 percent among 57 samples of drinking water, 15.8 percent among 19 samples of sewage, 7.1 percent among 42 samples of dishtowel, 0.1 percent among 780 samples of house fly and 5.0 percent among 40 samples of house rat.
