Studies On The Aetiology, Epidemiology And Pathology Of Paragonimus Infection In Fujian

The present article deals with the biology, epidemiology and pathology of Paragonimus from Fujian, China . The results are as follows1. Six species of Paragonimus, namely P.\vestermani, P. skrjabini, P.cenocopiosus, P. asymmetricus, P. fukianensis and P minqinensis were studied, Particularly on the specific characteristics and the various stage of life cycle of the important pathogenic agents, P. westermani and P. skrjabini were carefully studied and described.2.A detailed comparison of morphology, involving adult worm body feature, body spine, the ratio of length and width, size of oral and venteral suckers, morphology of ovary and testes and on the structure of metacercaria etc., were made between P.westermani and P.asymmetricus collected in Fujian. The morphological comparison indicated that P.westermani and P.asymmetricus appeared no specific difference, and the author so that recognized both species of lung flukes to be the same worms, and P. asymmetricus is the junior synonym of P.westermani.3. Whether one or three species among P.skrjabini, P. suechuanensis and p.heutungensis had been disputed and discussed for a long period of 40 years, and there still had no general agreement on the relation of these three species of Paragonimus. A careful comparison of morphology on the adult worms and various stage of life cycles among p.skrjabini, P. suechuanensis and P. heutungensis were made and summarized in table 5.6.7. As shown by table 5.6.7 the author considered that these three species of paragonimus appeared to be thesame species, P. suechuancnsis and P.heutungensis are the junior synonyms of P. skrjabini.4. So far as we know, the life cycle of P.cenocopiosm had never been described. Liu et al (1981) reported a kind of special cercaria obtained from Semisulcospera libertina and suggested it to be the cercaria of P.cenocopiosm. Therefore, they recognized that 5". liberthina served as the first intermediate host for P.cenocopiosus. Our field examinations were made on 1, 3960 old S.libertina in the endemic region of Shanyange, and all of them were negative with cercaria of Paragonimus. Besides, 3372 new-born S libertina infected with a large number of P.cenocopiosus miracidium under our laboratory condition, and no positive snails were found to harbour the cercaris of P. cenocopiosus 75-150 days after infection. Both our field and laboratory works clearly showed that S. libertina did not serve as the first intermediate host for P. cenocopiosus, and our results also clarified the unreal report by previous author.5.In the endemic region of P. cenocopiosus, 4 Species of fresh water crabs had demonstrated to be the second intermediate hosts of Paragonimus. Among them, two species of crabs indentified by crustacean specialist to be new to science, and given the names :(1) Sinopotamon pinghensis sp. nov,(2) Nanhaipotamon shanyangensis sp. nov,6. The epidemiology of Paragonimus Infection in Fujian was briefly discussed and concluded at the end of this paper. Seven species of Paragonimus had been reported from Fujian, P. westermani and P. skrjabini were most important pathogenic agents. Four species of fresh water snails were proved as the first intermediate hosts, and having eight species of fresh water crabs served as the second intermediate hosts. In the endemic area, human Paragonimus infection had been proved to be eaten raw or partially cooked crabs.