In an attempt to determine the incidence of the cercarial larvae of trematodes, Semisulcospira snails collected in Judong stream, an endemic area of Paragonimus westermani, in Kyungpook Province, Korea, were examined from 1965 to 1980. The infestation rate for cercariae in the snails was 5.4 per cent, but in 1970 dropped to 4.0 per cent and remained at the same level, 4.2 per cent, in 1975. It then decreased to 3.5 per cent in 1980. Seven species of cercariae, Cercaria incerta(Kobayashi, 1992) Faust, 1924, Cercaria nipponensis(Ando, 1915) Faust, 1924, Cercaria yoshidae(Osafune, 1898) Cort et Nichols, 1920, Centrocestus armatus(Tanabe, 1922) Yamaguti, 1934, Metagonimus species, Notocotylus magniovatus Yamaguti, 1934, and Paragonimus westermani(Kerbert, 1878), and five kinds of undeterminced cercariae were found. Of these, the most freqently emerged cercaria was Metagonimus species, folllowed by Notocotylus magniovatus. The least freqently emerged was Paragonimus westermani, with the rate of 0.04 per cent. The liberation rates in the five kinds of undetermined species varied from 0.04 to 0.15 per cent. In the monthly liberaton rates for cercariae, the highest rate was encountered in May, and decreased in the period from June to November. It then somewhat increased again in December. There was no correlation in the liberation rate for cercariae and length of snails. The results of this study indicate that the infestation of Semisulcospira snails with the cercariae of trematodes has decreased over the fifteen year period from 1965 to 1980.
For seven years from 1962 to 1968, fecal specimens of the patients were examined not only for the discovery of intestinal protozoa and helminths, but also to provie data on the incidence of intestinal parasites among the residents of Kyungpook Province, Korea. The Formalin-ether sedimentation, Lugol solution, and Heidenhain's iron-hematoxylin stained films were prepared for the recovery of intestinal parasites. Of 2,414 samples of feces examined, 35.7 percent were found to be infected with one or more species of protozoa. Among six species of protozoa detected, Entamoeba coli was observed most frequently(15.3%) followed by Entamoeba histolytica (11.9%), and then the Enteromonas hominis least often(1 case). For the survey of helminth, of a total of 5,288 fecal specimens examined, 86.7 percent were positive for one or more species of helminths. Trichocephalus trichiurus revealed the highest infection rate (83.6%), while Trichostrongylus orientalis was next (61.6%), and Ascaris lumbricoides was unexpectedly low(40.9%). The incidence for hookworm and Clonorchis sinensis was 22.4 percent and 29.8 percent respectively. Triple infections were found more frequently than double infections, and mixed infections of six or more species of helminths were observed in 3.8 percent of specimens.
This study was undertaken to evaluate the effects of health education and anti-Clonorchis campaign conducted in Kyungpook Province and to compare the prevalence of Clonorchis sinensis among the residents in the same areas for the period 1964-1976. Both surveys were made on all age groups of residents ranging from 0 to over 60 years of age. They were examined using primarily intradermal tests with Clonorchis and Paragonimus antigens and followed by stool examinations. The definitive diagnosis of clonorchiasis was made on the recovery of Clonorchis eggs from the stools. A marked reduction in the prevalence was encountered in the youngest age group, but there is no significant difference in the older age groups. The overall prevalence rate for clonorchiasis was reduced from 27.7 to 19.6 per cent in a period of 10 years. It is found that clonorchiasis is less prevalent in Kyungpook Province than it was a decade ago and it continued to decline.
The effects of pre-corrosion and applied potentials in artificial seawater on the S-N fatigue behavior of X80 steel were examined. The X80 specimens were pre-corroded in a FeCl3 solution for varying immersion times ranging from 0 to 96 h and subsequently S-N fatigued in air. It was found that the resistance to S-N fatigue decreased abruptly with 1 h immersion, while it became saturated with a further increase in immersion time. The trend observed in this study was relatively well explained by the stress concentration effect from the presence of corrosion damage on the surface. The in-situ S-N fatigue tests were also conducted on X80 steel in artificial seawater under applied potentials of-600,-850 and-1,050 mV (SCE). The fractographic and micrographic analyses were conducted on the fatigue specimens to identify the optimum cathodic protection conditions.
In order to determine the prevalence of Necator americanus, 182 fecal samples were collected from school children in the Taegu vicinity. These sample were subsequently cultured by the Harada-Mori technique. Necator americanus was differentiated from Ancylostoma duodenale using the bases of morphological characteristics of filariform larvae. Necator americanus was not found in the vicinity of Taegu.
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