Studies of the water analysis of the breeding place of the first intermediate host(Semisulcospira libertina) was carried out. The breeding place of Semisulcospira libertina in the Haenam area were found mainly in pebbly and sandy riverbed of the upper stream and halfway up the Donghae river, but we could not find the habitats of Semisulcospira libertina in the spring, paddyfield and tidal part of flow in which the content of Cl ion, Ca ion, total alkalinity, total hardness and pH were obviously higher than those of the breeding place. The range of physical and chemical characters of the Semisulcospira libertina breeding water were as follows. 0.05-0.7 m/s of optimal flowing velocity of fresh water, 20-50 cm in depth, 7.12+/-0.17 of optimal pH range 19.4+/-4.92(mg/l)in total alkalinity, 9.4+/-2.97(mg/l) of Ca ion, 9.8+/-2.3(mg/l) of Cl ion content, 115.1+/-34.2(mg/l) of total hardness, but there were no remarkable differences between the habitat water and the contrasts in their specific gravities. In the comparison of analytical result of the breeding water at Haenam, the content of Ca ion, Cl ion, total alkalinity, total hardness and pH showed a gradually higher value in the lower reaches of the river than those of the upper stream and halfway up the river.
parasitology-snail-intermediate host ; Semisulcospira libertina ; breeding place

In order to determine the epidemiological pattern of the Paragonimus westermani, the infestation rates of the cercarial and metacercarial larvae of digenetic trematodes in the snail and crayfish host, and the prevalence of Paragonimus westermani among the residents in the vicinity of the stream Namdae, Wyangpi, and Kwang, in the Ulchin county, Kyungpook province were studied from March to October in 1984. The population density of the snails per square meter of the habitats ranged form 5 to 25, with average of 15. Among the seven habitats, one, Ducheon, had snails infested with the cercariae of Paragonimus westermani, and the proportion of infested snails was very low, the average being 0.152 per thousand. Of six hundred and four crayfish examined, 113 or 18.7 per cent harboured the encysted larvae of Paragonimus westermani. A high infestation rate for the metacercariae in the crayfish was found in two habitats; 39.0 per cent in the Ducheon and 21.6 per cent in the Sokwang. The prevalence of Paragonimus westermani among the residents in Ulchin county was relatively high, 25.8 per cent by the Paragonimus intradermal tests and the difference in the rate of infection between males and females was found to be significant(t>2). The results obtained in this study indicate that endemic foci of Paragonimus westermani exist in Ulchin county and the prevalence of this lung fluke among the residents is relatviely high.
parasitology-helminth-trematoda ; Paragonimus westermani ; paragonimiasis ; epidemiology ; intermediate host ; crayfish ; snail ; metacercaria