The Morphological Study On Paragonimus Heterotremus From Different Geographical Areas

[Objectives] This paper involved the epidemical study of P. heterotremus in Maguan,Yunnan province,the observation and measure of adult worms, metacercariae and ova of P. heterotremus and the observation of surface structure of adult worms of P. heterotremus from Maguan and Vietnam with scanning electron microscope(SEM). From these.we expected to supply the morphological information ,reseach the morphological variation of geographical isolates ,study the significance of the shape and arrangement of cuticular spines for identifying species .[Methods] Crabs were collected in Maguan,Yunnan province where P. heterotremus were reported.Metacercariae were separated,identified and fed to a cat from which adult worms and eggs were obtained.Living metacercariae, adult worms and eggs were observed and measured with light microscope.Surface structure of adult worms from Maguan and Vietnam was observed with SEM in high and low vacuum environment. [Results] The metacercariae of P. heterotremus from Maguan were elliptic in shape and had a thin outer cyst and thick inner cyst.They were 266.97±22.25 in length and 248.98±22.51um in width. The inner cyst walls were progressively thickened toward each pole,measuring 13.349±2.966μm at the pole and 3.937±2.02μm on the side. Adult worms had an average size of 12.58±1.51x7.1±1.01mm.The average rate of width to length was 1 : 1.78.The oral sucker was more bigger than the ventral sucker and the average rate of two suckers in diameter was 1.89 : 1. The natural infection rate of the second intermediate host with P. heterotremus from Maguan was 75%.The rate of adult worms recovered from experimentally infected cat was 60%.With scanning electron microscopic observations,there were only single spines spaced on the abdomen of adult worms and no papillae were seen around oral and ventral suckers.In the high vaccum environment ,all spines of adult worms from Maguan were finger-shape and seemed to be tadpole-shape with the hollow on itHowever, there were half loop-shape spines on the abdomen of adult worms from Maguan in the low vaccum environment.In the same environment ,five kinds of spines were observed on the abdomen of adult worms from Vietnam including triangle,shark mouth,mound,scale and half loop-shape.[Conclusions] It is a epidemic region of P. heterotremus in Maguan,Yunnan province. Metacercariae with elliptic shape and double cyst walls is 266.97±22.25x248.98±22.51um in siz The inner cyst wall is thicker than outer cyst wall and become more thicker toward each pole.The spines of adult worms appear to be single shape with morphological variation among geographical isolates.Cat is the appropriate experimental definitive host.