Studies on the Genetic Variation and Speciation in the Paragonimus westermani Group in Asia

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The present study is to deduce (1) the origin of the triploids of Paragonimus westermani of Japan and (2) what P. westermani is which was described by Kerbert in 1878. More than 5, 000. Paragonimus metacercariae were isolated from 1, 873 crayfishes (Cambaroides dauricus, C. shrenkii) collected in 3 provinces of north-eastern China in 1990. They were identified as P. westermani based on their morphology as well as that of the adults. The flukes, especially from Liaoning Province were proved to be diploid, triploid and tetraploid types. The triploid fluke from China was almost the same as Japanese one not only in host-specificity but also in electrophoretic patterns. In the diploid fluke, Chinese populations were polymorphic in electrophoretic patterns, while Japanese ones were monomorphic. The specific alleles of Japanese triploid were found, with high frequency, in the diploid populations in China. Therefore, a certain diploid population of this fluke in north-eastern China seems to be … More related to the ancestor of Japanese triploid in terms of the gene introgression. Thirty-six Paragonimus metacercariae were isolated from 79 crabs (Potamiscus manipurensis) collected in Manipur, India, in 1990. They were provisionally classified into 2 groups. The morphology of the adult originating from P. westermani type metacercariae was in good agreement with the description of P. westermani by Vevers (1923), but not by Kerbert (1878). Eight hundred forty-three Paragonimus metacercariae were isolated from 570 crabs (the same as above) collected in Manipur, India, in 1991. They were provisionally classified into 4 groups. Seven hundred seventy-three Paragonimus metacercariae were isolated from 205 crabs (Phricotelphusa spp., Ranguna smalley) collected in southern Thailand, in 1991. They were classified into 2 groups. Further studies on Indian and Thai Paragonimus are now in progress. Epidemiological studies on human paragonimiasis as well as further biological studies on the flukes which are causative agents of this disease in India are highly important, because a great many of patients of paragonimiasis and multiple Paragonimus species have been found there. Less