Revision for “Metorchis conjunctus” created on June 18, 2014 @ 12:42:08
| Title | Metorchis conjunctus |
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| Content | <p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><i><b>Metorchis conjunctus</b></i></span></span><span style="color: #000000;"><span style="font-size: large;"><b> (Cobbold, 1860) Looss, 1899</b></span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>ETYMOLOGY:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Meta </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>conjunctus </i></span></span><span style="color: #000000;"><span style="font-size: medium;">= joined</span></span></p>
<p align="JUSTIFY"><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 conjunctum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Cobbold, 1860; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis noveboracensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Hung, 1926; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis intermedius</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Price 1929; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis canadensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Price, 1929; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis manitobensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Allen and Wardle, 1934.</span></span></p>
<p align="JUSTIFY"><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 using specimens from the biliary ducts of a red fox that died in the Gardens of the British Zoological Society in London. Cameron (1944) examined the taxonomy 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;"> and stated that he believed there to only be three species: </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in North America, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis albidus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> (Braun, 1893) Looss, 1899 in Europe and around the Mediterranean, and </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis felis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Hsü, 1934 in Asia (</span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis felis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> is considered here as a synonym of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis orientalis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Tanabe, 1919.).</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>GEOGRAPHIC DISTRIBUTION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> North America, most reports are from Canada and the northern parts of the United States. Under the name </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parametorchis noveboracensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, the parasite was reported from a cat in Ithaca, NY, USA (Hung, 1926), and it has been reported from a dog in South Carolina, USA (Jordan and Ashby, 1957).</span></span></p>
<p align="JUSTIFY"><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;"> Bile ducts.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>PARASITE IDENTIFICATION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Specimens of </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;"> differ from those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Amphimerus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </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;"> and </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;"> in that the uterus is more bunched together, "rosettiform," than in </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;"> and with branches that encircle the ventral sucker. </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;"> spp. also tend to be broader than the Opisthorchin relatives. The vittelaria of </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;"> are confined to the lateral margins of the body while 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 vittelaria from the lateral sides become confluent anteriorly. 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></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> Adult flukes measure from 1 to 6.6 mm in length with widths of 0.6 to 2.6 mm. The oral sucker is about the same size as the ventral sucker. The testes are situated in the third quarter of the body, tandem or slightly oblique, and tend to be round in outline. The eggs are yellowish brown with a distinct operculum and measure 22 to 32 µm long by 11 to 18 µm wide. The eggs contain an embryo when laid.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>LIFE CYCLE:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Cameron (1944) examined the life cycle using material from Quebec, Canada. The snail hosts include specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Anicola limosa</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The snail becomes infected when it ingests the egg. The cercaria is about 0.9 mm long, has a tail fin, and eye spots, and a potential life outside the snail of 60 to 72 hours. The cercariae enter and encyst in the muscles of fresh-water fish (the common sucker, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Catostomus commersoni</i></span></span><span style="color: #000000;"><span style="font-size: medium;">), mainly the lateral muscles extending from the dorsal fin to the tail. In experimentally infected cats, eggs were found in the feces beginning 4 weeks after infection, and the flukes have been found capable of living in cats for at least 5 years.</span></span></p>
<p align="JUSTIFY"><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;"> Watson and Croll (1981) reported the clinical changes in cats experimentally infected with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis conjuntus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Cats given 200 metacercariae did not develop signs of infection, although they did display a marked eosinophilia and increased serum alanine aminotransferase and leucine aminopeptidase levels. In cats give 300 metacercariae, there were significant clinical signs that developed around patency (which in these studies was 17 days after infection). The cats occasionally developed icterus, bloody urine, and severe diarrhea that disappeared and then recurred over the next few months. The eosinophilia became much less obvious in chronic infections. Primary infections did not seem to prevent the establishment of secondary infections with this parasite. Hyperplasia of the biliary epithelium was the main pathology described in naturally infected cats from Ontario, Canada. (Mills and Hirth 1968)</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> Disease due to natural infections has been described. Axelson (1962) described lesions in the liver and bile ducts of a cat that also presented with lymphoma. Large numbers of flukes were present with around 200 being in the gall bladder. The bile ducts were markedly enlarged with signs of chronic cholangohepatitis. Another case was described by Essex and Bollman (1930) where cirrhosis formed in a 5-year-old Persian cat from Rochester, Minnesota, USA, due to a mixed infection with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Opisthorchis pseudofelineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> and </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis complexus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> (the photograph of the specimen clearly shows the vitellaria and would indicate that this was actually an infection with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metorchis conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">). The cat became emaciated, and developed ascites and jaundice. At necropsy, there was a hard, enlarged, grayish liver, with no nodules of the surface. The walls of the bile ducts were thickened. The bile contained numerous trematode eggs. There was extensive hyperplasia of the entire biliary duct system and few normal hepatic cells in any histologic section of the liver.</span></span></p>
<p align="JUSTIFY"><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></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"> Other hosts, including the red fox and the wolf, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Canis lupus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, have been found infected with this parasite (Wobeser</span></span><span style="color: #000000;"><span style="font-size: medium;"><i> et al</i></span></span><span style="color: #000000;"><span style="font-size: medium;">., 1983). Other hosts include the raccoon, the gray fox, mink, dogs. The range of the parasite seems to be restricted by the range of the snail intermediate host.</span></span></p>
<p align="JUSTIFY"><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></p>
<p align="JUSTIFY"><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;"> Cameron (1944) states that the eggs of this parasite were observed in the feces of a human being in Saskatchewan, Canada.</span></span></p>
<p align="JUSTIFY"><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></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>REFERENCES:</b></span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Axelson RD. 1962. </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;"><i>conjuctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> liver fluke infestation in a cat. Can Vet J 3:359-360.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Cameron TWM. 1944. The morphology, taxonomy, and life history of </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;"><i>conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> (Cobbold, 1860). Can J Res 22:6-16.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Essex HE, Bollman JL. 1930. Parasitic cirrhosis of the liver in a cat infected with </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>pseudofelineus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> and </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;"><i>complexus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Am J Trop Med 10: 65-70.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Hung SL. 1926. A new species of fluke, </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;"><i>noveboracensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, from the cat in the United States. Proc US Natl Mus 69:1-2.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Jordan HE, Ashby WT. 1957. Liver flukes (</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;"><i>conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">) in a dog from South Carolina. JAVMA 141:239-240.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Mills JHL, Hirth RS. 1968. Lesions caused by hepatic trematode, </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;"><i>conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, Cobbold, 1860. A comparative study in carnivora. J small Anim Pract 9:1-6.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Watson TG, Croll NA. 1981. Clinical changes caused by the liver fluke </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;"><i>conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in cats. Vet Pathol 18:778-785.</span></span></p>
<p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Wobeser G, Runge W, Stewart RR. </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;"><i>conjunctus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> (Cobbold, 1860) infection in wolves (</span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Canis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>lupus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">), with pancreatic involvement in two animals. J Wildl Dis 19:353-356.</span></span></p> |
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