Study The Development And Pathogenicity On Clonorchis Sinensis In Mice

Objective： To investigate the Metacercaria(Clonorchis sinensis)infection of freshwaterfishes in the Nenjiang water area of Qiqihaer region.To find out the epidemic factors ofclonorchiasis in the area.Polypide development and liver pathobiology were examined inanimals infected with different number of larvae of Clonorchis sinensis.It could providethe scientific basis on the study of morphological and pathological on Clonorchissinensis,and formulate some prevention and control measures for relevant departments.Methods：Nine species of freshwater fish totally1175speciments were taken from theNenjiang water area of Qiqihaer region. The direct compression and artificial digestion（pepsin-HCl）method were used to check the infection rate and average degree ofmetacercaria of Clonorchis sinensis,The administration by gavage was used to infect KMmouse,The mice were sacrificed on5days、10days、15days、20days、25days、30daysafter infection,and then to observe the morphous of larvae of Clonorchis sinensis.Theliver tissues were taken from the mice on10days、20days、30days after infection forpathological examination.The procedure included the fixed of body with5%-10%formaldehyde solution,paraffin section,and HE staining,observed the pathologic changesby microscope.The data were statistically analysed by Chi-square test.Results：Metacercaria of Clonorchis sinensis were discovered in eight species offreshwater fish except of Silurus asotus.The infection rate of Carassius auratus、Pseudorasbora parva、 Erythroculter ilishaeformis、 Longnose gudgeon、 Phoxinuslagowskii Dybowski、Perccottus glenii、Rhodeus sinensis、Abbottina rivularis and Silurusasotus were45.92%(45/98)、41.64%(117/281)、35.71%(20/56)、82.73%(91/110)、74.48%(108/145)、7.14%(6/84)、60%(126/210) and59.73%(89/149) respectively,and thetotal infection rate was51.23%（607/1175. Our results showed there were importantdifferences in the infection rate of Metacercaria of Clonorchis sinensis across the different species of fish(χ2=166.943,P＜0.05).The highest infection rate was found inLongnose gudgeon,and the highest average degree were found in Carassius auratus andPseudorasbora parva.The infected site in all eight species of freshwater fish weredifferent significantly, Except the cerebrum all the site could be Infected in Carassiusauratus and Pseudorasbora parva. For the different river region the infection rate ofMetacercaria of Clonorchis sinensis were important differences(χ2=115.51,P＜0.05).Theanimal experimental results showed that, the KM mice was a well characterized mousemodel of clonorchiasis sinensis.The experiment data showed, the achievement ratio of themetacercaria of Clonorchis sinensis in the infected KM mice which be administered bygavage was96%. With the extension of the infection time, the length and width of worm,the diameter of the oral sucker、ventral sucker and throat, the length of uterus and testis ofclonorchiasis sinensis were increasing obviously，and the ratio on the spacing from oralsucker to ventral sucker and the whole worm body was reduced significantly. The eggs inutero could be observed on fifteenth days in infected mice,and the testis branch can beobserved obviously in twentieth days in infected mice. The pathological change in theliver of KM mice showed that a large number of worms in the hepatic bile duct of micecould be found.The pathological changes including inflammation、eosinophilic abscesses、fibrous tissue hyperplasia、the walls of hepatic bile ducts had thickened and so on coulebe observed.Conlusion：1.Qiqihae area is endemic area of clonorchiasis,where8species of freshwaterfish are all infected by Clonorchis sinensis metacercaria,in which the wild Carassiusauratus and Pseudorasbora parva are the most serious. The parasitic position ofMetacercaria in the muscle is the most serious infection, and the infection are relativelylight in the scales of fish、fish-skin、the gills of fish and other parts.There are significantlydifferences among Clonorchis sinensis metacercaria infection rates in the different riverregion、the different species of fish and the different infection site.2. The KM mice are suitable as the animal model which be infected by metacercaria ofClonorchis sinensis.On the one hand,low price;on the other hand, the experimentaloperation of metacercaria infection is simple by gavage method,and the sucsess rate ofinfection is high.The Clonorchis sinensis can grow rapidly and the pathological changes of liver in mice can be found obviousely,which have a certain reference for the study thedevelopment and pathogenicity of Clonorchis sinensis who parasitic in the human body.