This study was carried out in order to find out the valuable measure to kill the parasite eggs in night soil. The fresh eggs of Ascaris put into human stool were irradiated with Cobalt 60 of 200,000 to 1,000,000 rad and cultured in test tubes at 25-30 C, washing with 2 percent formalin solution every 24 hours. The continuous development of those eggs were observed under microscope and the proprotions of developed eggs were compared with those of control groups. The major result can be summarized as follows: In general, The eggs in stool developed poorly than the eggs in saline. If the eggs were irradiated with the larger dose of Cobalt 60, the proportion of developed eggs were reduced subsequently. The eggs irradiated with the dose of 1,000,000 rad in saline developed in the proportion of 15.5 percent, whereas irradiated with 200,000 rad 94 percent developed in 4 weeks. The 44.5 percent of eggs in stool irradiated with 200,000 rad developed after 4 weeks, 30.5 percent with 300,000 rad, 25 percent with 500,000 rad and 3.5 percent with 1,000,000 rad respectively. The effective minimum dose of Cobalt 60 irradiation to kill the Ascaris eggs in stool was estimated 1,000,000 rad. Further examination will be required to observe the infectivity of irradiated Ascaris eggs to animals and to evaluate the effect from the standpoint of sanitary engineerings.
parasitology-nematode-Ascaris lumbricoides ; Cobalt 60 ; radiology ; prevention ; egg ; infectivity

The eggs and rhabditoid larvae of canine hookworm were irradiated with ultraviolet rays for one hour at a distance of 10, 20, 30, and 40 cm. The infective stage larvae of the same parasites were irradiated for l, 3, 5 and 14 hours from the same distances. The infective larvae were also exposed under direct sunlight for l, 2, 3 and 4 hours. Parasites: Ancylostoma caninum was used. Eggs were collected in vitro from female adult worms. The worms were kept at 37 C in petri-dish filled with Kreb's Ringer solution. There was an average of two cell stages, and they were used as early as possible before the morula stage. Rhabditoid larvae were obtained by culture of the above eggs for twenty-four hours in 25 C incubator. The larvae reached the infective stage in seven days culture at the same condition. Irradiation of Ultraviolet Ray: Kingston ultraviolet light (100 volt, 10 watt, 50 cycles, 0.230 ampere) was used. The potential U.V.R. power was 1.8 watts. The distances between the material and the light were 10, 20, 30 and 40 cm at a temperature of 25 C in each case. The samples were smeared on the tile in order to keep them in saturated moisture. Fully wetted ten ply gauze was laid underneath the tile. The tile was surrounded by 2x5 cm rectangular piece of glass in order to prevent the spread of the larvae to the outside. All of the samples received irradiation for one hour and were cultured for a period of seven days. The hatching of the egg and the development of the larvae were observed. For the purpose of the study, the infectivity and pathogenicity of the irradiated samples, were inoculated into mice orally. The lungs, livers and carcass were examined three days after the infection. A routine pathological examination of the organs was also carried out. In order to study the eggs productivity, the larvae were given to the proper host, dog. The eggs in the feces were examined from three to 6 weeks after infection, both quantitatively and qualitatively. As a supplementary experiment, the infective larvae of canine hookworm were exposed four hours under direct sunlight (September 25), and the infectivity and pathogenicity of the host were examined. Hatching, development and infectivity of irradiated eggs: Hatchability of the irradiated group for one hour according to the distance from the light to the sample were 48.0 percent at 10 cm, 60.3 percent at 20 cm, 85.2 percent at 30 cm and 88. 2 percent at 40 cm respectively. None of them developed to the infective stage. They remained rhabitoid for several days and were destroyed. None was found alive in the host. 93.0 percent of the control group hatched and developed to the infective stage. Development and infectivity of irradiated rhabditoid larvae: None of the irradiated group reached the infective stage. Under irradiation they coiled and died soon after straightening out again. Only the group irradiated at the distance of 40cm survived for six days. They finally granulated. There was no manifestion of irradiated larvae alive in the host tissue. Life span, infectivity, pathogenicity and egg-productivity of the irradiated infectve stage larvae: All were destroyed in the group of fourteen hours irradiation at 40 cm distance. Thirteen precent survived in the five hours irradiation group at the same distance. The survivability of larvae was reduced by the period of irradiation and at the shortest distance. The infectivity to mice was only 0.8 percent at 30 cm, and 8.2 percent at 40 cm in the three hour irradiation group. The recovery of the infected larvae from the host tissues was reduced as the irradiation period was increased and the distance shortened. The pathogenicity was paralleled with the vitality of the irradiated larvae. From the groups of one hour irradiation and ten cm distance, three hour irradiation and ten to thirty cm distance, the egg-productivity was all negative. But as the irradiation period decreased and the distance lengthened the egg-productivity tended closer to normal. The infective stage larvae which were exposed to direct sunlight were destroyed within three hours, but survived 81 percent in the one hour exposure group and 20 percent in the two hour exposure group. The summary of the results is as follows: The hatching of eggs was reduced to half for one hour irradiation at the ten cm distance. Even hatched larvae did not develop to infective stage. Infectivity was inhibited by the irradiation to at the ten cm distance for one hour. About ten percent of the irradiated infective stage larvae were recovered from the infected animal among the group of 40 cm distance for one hour. The egg-productivity became lower in the group of one hour irradiation at 40 cm distance. The pathogenicity of the irradiated group was mild compared to the control group. The direct sunlight destroyed the infective stage larvae within three hours. In general, the ultraviolet ray showed the inhibitory action in the hatching, development, pathogenicity and egg-productivity of the hookworm. The grade was paralleled with the period of irradiation and reversed to the distance between the light and samples.
parasitology-helminth-nematoda-hookworm-Ancylostoma caninum ; irradiation ; development ; infectivity ; ultraviolet ray

To observe the possibility of human visceral larva migrans due to eating of raw liver of domestic animals, especially of cattle, and also to serve as a good reference for adequate sanitary measures, the investigation survey was carried out from May 1975 to May 1976. From the subjects of a l,048 inhabitants (male 558, female 490) in five localities including two Provinces and three different cities, food habit was studied by questionnaire mannual. Larvae isolated from liver tissues of cattle, and pig were identified. Experimental observation on the chicken and mice infected with Toxocara canis was undertaken to draw a assumption of possibility inducing human visceral larva migrans. The results obtained from the present study are summarized. A part of Korean people has the habit to eat the livers of cattle, fowl, pig and dog raw. Eating rate of raw beef liver was 37.8 percent out of l,048 inhabitants, and its rate was higher markedly in male(57.7 percent) than in female (15. 1 percent), and the highest rate among the group of 31-40 years old. Eating rate of raw liver of fowl was 5.9 percent, pig 5.3 percent, and dog 2.5 percent. Larva recovery rate from beef liver was 11.8 percent out of 195 samples and 72.0 percent of total detected 1arvae were identified as Toxocara(=Neoascaris) vitulorum. From pig liver, larvae of nematoda were found in 6.4 percent out of 109 samples but no larva was detected from 120 fowl livers. Larvae detected from one-half of tissues and organs of infected chicken with about 2,000 Toxocara canis eggs were 8-245 in number, and 85-100 percent of recovered larvae were from their 1iver tissues. Toxocara canis larvae, 45, 31, 42 and 23 in number at 3rd, 14th, 25th and 55th day in one-half of the tissues and organs after infection respectively, were demonstrated from the mice infected with 500 larvae collected from infected chicken liver. Most of the larvae were recovered from the carcass of the mouse. It was approved the larvae isolated from chicken possess infectivity to the mice. Typical eosinophilic granulomatous change was not observed in the liver tissue of the infected chicken at 20th day after infection. As it summarized above, the liver of various domestic animals is the favorite tissue for migration of nematodes larvae. Therefore, the possibility of human visceral larva migrans may be induced due to eating of raw liver of domestic animals.
parasitology-helminth-nematoda ; visceral larva migrans ; Toxocara canis ; liver ; cattle ; fowl ; pig ; dog ; mouse ; chicken ; infectivity