[Larvicidal action of liquid nitrogen against metacercariae of Clonorchis sinensis]

The author investigated the larvicidal action of liquid nitrogen against the metacercariae of Clonorchis sinensis, with an observation on the freshness and change of taste in the flesh of fishes. The results obtained were as follows: The metacercariae in the flesh of Pseudorasbora parva, which were treated with liquid nitrogen (-192C), were not killed within 10 seconds, but completely killed over 30 seconds. In comparison, the metacercariae in the flesh of P. parva kept in a refrigerator (-12C) were killed only in 84 percent in 10-hour exposure group. The freezing speed of fishes by liquid nitrogen was 4 min. (') and 15 seconds(") for Cyprinus carpio, 1'22" for Carassius carassius and only 30", for Pseudorasbora parva. As for the freshness and taste of raw fresh water fishes, they were not deteriorated after the treatment with liquid nitrogen. In animal infection experiment of C. sinensis metacercariae after freezing, they were found not infective after they were treated with liquid nitrogen. From the results, it is inferred that the treatment of fresh water fishes for longer than 30 seconds with liquid nitrogen is helpful to reduce the possibility of C. sinensis infection without alteration of the freshness and taste of fishes.

[Studies on beta-glucuronidase activities in liver, stomach and small intestinal tissues of rabbits infected with Clonorchis sinensis]

The author has studied the beta-glucuronidase activity in several tissues such as liver, stomach and small intestine of the male and female rabbits infected with different doses of metacercariae of Clonorchis sinensis. The metacercariae of Clonorchis sinensis were isolated from Pseudorasbora parva caught in Kim Hae by digestion technic. The experimental animals were sacrificed in the period of 1, 7, 14, 21, 28 and 35th days following the infection. The results obtained were summarized as follows: In the groups infected with 100 metacercariae, beta-glucuronidase activity was slightly increased during the entire periods than control rabbits. It was the highest in the first day with 1.535 and 1.421 mu/g, 14th days with 2.521 and 2.200 mu/g, and then lowered by the time, gradually. In the groups infected with 500 metacercariae, beta-glucuronidase activity was highly increased on the first day with 1.535 and 1.866 mu/g than that 100 metacercariae groups according to each organs. It was the highest on the 7th day and 14th day. In the groups infected with 1,000 metacercariae, beta-glucuronidase activity was remarkably increased in the first and 14th days according to each organs, and then lowered gradually day by day. beta-glucuronidase activity of all organs was more increased than that of normal organs and the highest activity in the liver with 2.521 mu/g, intestine(1.612) and stomach (1.581) respectively. beta-glucuronidase activity of rabbits was higher in the female than in the male. On the basis of these results, it was suggested that beta-glucuronidase activity was affected by the duration of infection and by the number of Clonorchis sinensis, according to the organs and sex of the rabbits.

Epidemiological studies of Clonorchis sinensis in lower area of Nag Dong river nearby Busan City in Korea.

The infection rates with cercaria and metacercaria of the Clonorchis sinensis in snail and fish hosts, and the prevalence among the inhabitants in the lower Nag Dong river in Busan were investigated in the period from June 1981 to March 1982. The stool examination and E.P.G. count for prevalence and intensity of clonorchiasis were done by cellophane thick smear and Stoll's egg count methods. The prevalence rate of clonorchiasis among inhabitants of 3 towns in Bug Gu, was 38.4% among a total of 1,384 persons examined. By town, the prevalence in Gu Po was 25.4% out of 330 persons examined, 39.3% in 438 examined in Gang Dong and 44.8% out of 616 in examined in Myeng Ji respectively. According to sex, the male(41.9%) showed relatively higher rate than female(35.3%). By age, increase of rate was observed as increase in age. The highest rate was 80.7% in 50~59 years group. The intensity of infection was light: 89.1% of examined cases were below 10,000 E.P.G.; by area 80.9%(Gu Po), 80.2%(Gang Dong), 97.3%(Myeng JI). Out of fresh water fish species collected, 2 species were not infected with metacercaria. The metacercarial detection rate from fish in low Nag Dong river showed 100% in Pseudorasbora parva, Pseudogobio esocinus(41.4%), Hemibarbus labeo(37.1%), Acheilognathus limbata(33.3%) and Erythroculter erthropterus(4.5%) respectively. The mean number of metacercaria per gram of muscle was 21.2 in P. parva, P. esocinus(15.0), H. labeo(11.9), A. limbata(6.3), and E. erythropterus(1.6) respectively. Though 7 area along Nag Dong river were surveyed for Parafossarulus manchouricus, the snails were not found at all areas except for one area, Seo Nam stream; and the cercaria was infected 0.9% out of 708 examined.

[Incidence of intestinal parasites with fecal examination on the out patient of Pusan University Hospital]

Author studied on the incidence of intestinal parasites with fecal examination on the out patient Pusan University Hospital, between from January to December 1969. The method employed were Formalin-Ether and flotation method in 3,510 for the prevalence rate of intestinal helminthes(Ascaris lumbricoides, hookworm, Trichocephalus trichiurus, Trichostrongylus orientalis). The following results were obtained: The positive rate of intestinal helminthes of total was 65.4 percent among 3,510 persons. The infection rate of Ascaris lumbricoides, hookworm, Trichocephalus trichiurus, Trichostrongylus orientalis were 19.3 %, 6.5 %, 55.2 % and 46.1 %. The female (66.4%) had definitely higher infection rate than male (65.0 %). The age group of 51-60 year of the male showed highest infection rate 75.4 % and the age group 31-40 year of the female showed highest infection rate 72.9 %.

[Epidemiological Studies On The Acaroid Mite]

Epidemiological study on Acaroid mite in dust different sites were carried out and the following results were obtained. 1. Tyrophagus dimidiatus, Chibidania tokyoensis and Ornithonyssus nagayoi were found in living room(46.2 %), bath room(36.7 %), garden(27.0 %), shopping-store(28.8 %) and ware-house (29.2 %) in the Pusan area. 2. Dermanyssus gallinae and Rhizoglyphus echinopus were found mainly in class rooms of girl's high school(34.0 %) and class room of girl's middle school(40.0 %) as well as in primary school(13.2 %), but they are not found in class rooms of boys high school. 3. Generally, the various mites were found in the living room(57.0 %), under the carpet(50 %), under the furniture(52.0 %), on the furniture(27.5 %), lavatory(35.7 %) and garden(23.8 %).