The Etiology Study On Paragonimus From Different Geographical Areas In Yunnan Province

[Objective] This paper involved the distribution of Paragonimus in Jinping country and Baoshan city,Yunnan province. Pathogens including metacercariae, excysted metacercariae, eggs ,adult worms were obtained from different hosts and they were observed and measured .The surface structure of adult worms were observed with scanning electron microscope(SEM). The sympathism of two hosts were compared .From these we expected to definite the genus relationship of Paragonimus from Jinping country and Baoshan city, to understand the infection condition of Paragonimus' host (rats , cats and crabs).[Methods] Crabs were collected from Jinping country and Baoshan city, Yunnan province. Metacercariae were separated, identified and fed to rats and cats from which adult worms and eggs were obtained. Metacercariae, excysted metacercariae, eggs and adult worms were observed and measured with light microscope. Surface structure of adult worms were observed with SEM.[Results] The shape of metacercaria from Jinping country and Baoshan city close to spherical. The capsule wall of metacercariae almost are monoptychial and the size of its from Jinping country are 0．401 mm×0．395 mm, from Baoshan city are 0．435 mm×0．433 mm. Adult worms are all elliptic in shape and the average size from Jinping country and Baoshan city are 10．107 mm×4．064 mm and 9．59 mm×43．577 mm respectively. The every rate of width to length of adult worms from Jinping country and Baoshan city are 1:2．49 and 1:2．63 respectively. The size of their ventral sucker larger than oral sucker. The ovary are all near the ventral sucker, its ' branches are simple. The testes' centrosome are small and its' length are about 1/6 of the body. With SEM observation there are single spines in the surface of adult worms, the spines before the ventral sucker are triangle and a sharp-pointed knife in shape, after the ventral sucker are almost half-moon in shape and the end of a few of spines are bifurcate. The morphology of metacercariae, excysted metacercariae, eggs from Jinping country are nearly resemble but there are few different from the morphology of its from Baoshan city. the morphology of adult worms are identical.The natural infection rate of the second intermediate host with Paragonimus from Jinping country and Baoshan city are 79．9% and 100%. The quantity of each crab infects metacercariae which were collected from Jinping country and Baoshan city are 1．8 and 13．3 respectively. The rate of worms recovered from experimentally infected rats and cats which infected metacercaria from Jinping country are 24% and 55%. The rate of worms recovered from rats and cats which infected metacercaria from Baoshan city are 5% and 67．7%.[Conclusions] They are all epidemic regions of Paragonimus in Jinping country and Baoshan city, Yunnan province. The infection rate of crabs from Baoshan city is higher than that from Jinping country.The epidemic Paragonimus in two places are both Paragonimus cheni (Hu, 1963 Chen, 1964) . But they have the morphological variation in difference place. The degree of Paragonimus infecting rats from Jinping country is higher than that from Baoshan city. The degree of Paragonimus infecting cats from Jinping country is similar with that from Baoshan city. But both are all higher than the degree of infecting rats. Cat is the suitable experimental host of P. cheni.