Opisthorchis felineus

Opisthorchis felineus

<p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><i><b>Opisthorchis felineus</b></i></span></span><span style="color: #000000;"><span style="font-size: large;"><b> (Rivolta, 1884) Blanchard, 1895</b></span></span></p> <p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><b>(Figure 2-39)</b></span></span></p> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>ETYMOLOGY:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opistho </i></span></span><span style="color: #000000;"><span style="font-size: medium;">= posterior and </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>orchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> = testis along with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>felineus </i></span></span><span style="color: #000000;"><span style="font-size: medium;">= representing the feline host.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>SYNONYMS:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma felineum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Rivolta, 1884; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma sibiricum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Winogradoff, 1892.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>HISTORY:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> This trematode was originally described from the bile passages of a cat in Italy (1884). In 1892, it was found in 9 human beings in Siberia. </span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>GEOGRAPHIC DISTRIBUTION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> is found in Siberia, areas drained by the Danube in Europe and the Volga in Russia. </span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>LOCATION IN HOST:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Gall bladder and bile ducts; occasionally in the pancreatic duct or the small intestine.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>PARASITE IDENTIFICATION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> is similar to </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Clonorchis sinensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, the most obvious difference is the difference in the amount of branching of the testes. Those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Clonorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are highly branched, while those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are lobed. The adults of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> differ from those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis viverrini</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> mainly in larval development and morphology; however, the eggs of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>O. felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are 30 by 11 µm while those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>O. viverrini</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are 27 by 15 µm.</span></span> <span style="color: #000000;"><span style="font-size: medium;"> Specimens of the genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> have much wider bodies and spherical testes. In the genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, the flukes have the vitellaria become confluent in the anterior body. In specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Pseudamphistomum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> the posterior end of the body is squared-off giving the ventral surface of the body the appearance of being a pseudo hold-fast structure.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>LIFE CYCLE:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> The life cycle is very similar to that of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Clonorchis sinensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The eggs hatch only after they are ingested by the appropriate snail (</span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Bithynia leachi</i></span></span><span style="color: #000000;"><span style="font-size: medium;">). Ultimately a cercaria develops that has eyespots and a large tail fin. The cercaria penetrates a fresh-water fish, typically of the carp family, between the scales and encysts as a metacercaria within the muscles. Cats become infected by eating infected fish. Once eaten, the fluke migrates through the ampule of Vater into the bile ducts where it matures (Vogel, 1934).</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>CLINICAL PRESENTATION AND PATHOGENESIS:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Little attention has been given the pathological manifestations that take place within the feline host. It is expected that the changes will be similar to those observed in human beings infected with this parasite. Besides cirrhosis due to periportal fibrosis, there have also been reports of bile stones forming around eggs causing cholecystitis. As the periportal fibrosis continues, there will be the development of edema and ascites.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>TREATMENT:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Praziquantel is likely to prove successful in eliminating these trematodes from many treated cases.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Cats are a major host of this pathogen. Throughout Europe, Siberia, and the Ukraine, infections of cats with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are not uncommon. In some parts of the parasite's range, the infection in maintained mainly in the human population, and improved sanitation among the human hosts will reduce the transmission of the parasite. Other hosts that have been reported to support the development of this parasite includes dogs, foxes, pigs,m martens, wolverines, polecats, gray seals, and bearded seals. </span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>HAZARD TO OTHER ANIMALS:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Dogs and other fish-eating mammals can also be infected with this parasite.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>HAZARD TO HUMANS:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Large numbers of human beings are infected with this parasite in the geographical regions where it is found.</span></span> &nbsp; &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>CONTROL/PREVENTION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Prevent the ingestion of infected raw, dried or pickled fish; these latter methods are not necessarily going to kill the metacercarial stage of the trematode.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>REFERENCES:</b></span></span> <span style="color: #000000;"><span style="font-size: medium;">Vogel H. 1934. Der Entwicklungszyklus von </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> (Riv.) nebst Bemerkungen über Systematik und Epidemioloie. Zoologica 33:1-103.</span></span> &nbsp; <span style="color: #000000;"><span style="font-size: medium;"><b>Figure 2-39.</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>felineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> from a cat. Note the slightly branched testes and the vitellaria that extend only to the anterior of the most anteriad testis.</span></span> &nbsp;