Studies on the incidence of the intestinal protozoa in the mountainous area of Chollapuk-do
Although intestinal protozoan infections have been found widely among various population in temperate, as well as in areas whereever field surveys have been donefor the human parasites, considerable differences on the prevalences of the infections have been indicated according to years, localities, groups and workers.
In Korea, whereas Choi (1926) reported 60% of incidence of the infection by six successive direct fecal smear method among 2,000 examinees in Seoul area, Soh et al. (1961) found 22.3% out of 10,320 samples among Severance Hospital out-patients by the formalin-ether concentration technic (M.G.L.), and no special age or seasonal differences. But, Chung et al. (1959) reported that clinical cases were predominant throughout the summer. Recently, Kim et al. (1971) reported (34.9%) incidence by direct smear, zinc sulfate floatation and formalin-ether concentration techniques among 2,250 specimens which were collected from 10 localities of different provinces.
A few research concerning the mode of amebic infestation has been reported in Korea. Soh et al. (1959) examined the roadside soil in Seoul area and found cysts of E. histolytiea 1, E. coil 3 and I. butschlii 1 among 19 samples. Kim (1967) reported that sources of infection by E. histolytica in Cheju-do were possibly
hog-feces, manure heap, drinking water or rats.
This study was undertaken in order to elueidate the prevalences of the intestinal protozoan infection according to localities and the mode of the infestation in the mountainous area of Chollapuk-do during the year 1970-1971.
MATERIALS AND METHODS
8,508 of focal samples were collected among the inhabitants of the mountainous area, which covered 18 myuns (-township) from 6 guns (-county) in the astern 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, hog-faces, manure heap, garden soil, sewage; dishtowel, dust in room and floor, fingernail dirt, house fly and house rat were examined by zinc sulfate floatation technic.
1. Rate of infection:
Among total 8,508 fecal specimens examined, 3,152 (37.0%) were positive for the intestinal protozoa; E. histolytica 9.8%, E. coli 25.6%, E. nana 7.2%, G. lamblia 6.8%, I. butschlii 0.6% and C. mesnili 0.7%. A single infection of protozoa was the highest (68.3%), and double infection (22.3%), triple, quadruple and quintuple infections were in decreasing order. The rate of E. coil was the highest (25.6%) and it indicated that the prevalence of E. coil was coincided with the incidence of E. histolytica.
2. Age and Sex distributions of the protozoa positives;
The highest distribution (39.8%) was observed in the group aging 41-50, and the lowest (27.3%) in the group above 61. The groups under 10 years showed a relatively high positive rate among all age groups. Male showed slightly higher (38.6%) than
3. Variation of prevalences according to localities;
Jangsoo-gun showed the highest positive rate (42.9%) and Namwon-gun was the lowest (32.5%). The prevalence of E. histolytica showed the highest (11.6%) in Imsil-gun and the lowest (6.9%) in Jangsoo-gun(6.9%).
4. The mode of the infestation; E. histolytica eyst was found 9.1% from total 99 samples of hog-feces and a considerable high rate of 33.3% from 12 samples which were fed with stool as a
fodder among 99, 4.8% among 78 samples of manure heap, 0.6% among 164 samples of fingernail dirt, 5.3% among 57 samples of drinking water, 15.8% among 19 samples of sewage, 7.1% among 42 samples of dishtowel, 0.1% among 780 samples of house fly and 5.0% among 40 samples of house rat.
The prevalence of the intestinal protozoan infection in the mountainous area of Chollapuk-do was examined during the year 1970-1971. Total 8,508 fecal specimens were examined and the mode of transmission was also studied.
1. The prevalence of the intestinal protozoa was 37.0% and that of E. histolytica and E. coli was 9.8% and 25.6% respectively.
2. The highest positive rate was observed among 41-50 age group, and male showed higher than female. And single infection was the highest and double, triple, quadruple and quintuple infections were in decreasing order.
3. E. histolytica and E. coli cysts were recovered from hog-feces, manure heap, drinking water, sewage and house rat.