Nanophyetus salmincola

Nanophyetus salmincola

<p align="CENTER"><span style="color: #000000;"><i><b>Nanophyetus salmincola</b></i></span><span style="color: #000000;"><b> Chapin, 1928</b></span></p> <p align="CENTER"><span style="color: #000000;"><b>(Figure 2-31)</b></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>Nano</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>phyetus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> = genitalia along with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>salmincola</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> = for the salmonid second hosts. </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;"> Chapin, 1926 first described this fluke as </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyes salmincola</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. He later (1928) changed the name to be </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus salmincola</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. A synonym or sister species from the Siberian coast is </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus schikhobalowi</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Skrjabin and Podiapolskaia, 1931. Another synonym is </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distomulum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>oregonensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Ward and Mueller, 1926. The genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> is also considered by some to be synonymous with the genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Troglotrema</i></span></span><span style="color: #000000;"><span style="font-size: medium;">.</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;"> The fluke was noted be associated with salmon-poisoning disease in dogs because salmon that did not contain metacercariae did not transmit the disease to dogs (Donham</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;">., 1926). The infectious agent was later identified to be </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Neorickettsia helminthoeca</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. This rickettsia is passed from dog to dog within the body of the fluke.</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;"> This trematode is found distributed around the northern Pacific Rim mainly in various species of canids. The cat does not appear to be a major host of this parasite (Schlegel</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;">., 1968).</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;"> Small intestine.</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;"> Members of the genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are small flukes, about 1 mm long. There is a muscular pharynx. The genital opening is just posteriad to the ventral sucker, with the ovary being at about the same level as the ventral sucker. The testes are large and are opposite each other in the middle of the hind body.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> The adult flukes may be anywhere from 0.8 mm to 2.5 mm in length. The eggs, 87 µm to 97 µm in length by 38 to 55 µm wide, are light brown in color, operculate, and are not embryonated when passed in the feces. </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;"> The miracidium within the egg, hatches and swims by means of its cilia. The miracidium develops into a redia within the body of the freshwater snail </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Oxytrema silicula</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Ultimately, cercariae are produced. The cercariae are microcercous, i.e., have a very small tail, and are grouped together by strands of mucus which probably help them come into contact with the surface of a fish swimming by. The cercariae penetrate the skin of fish at the site of contact. This fish hosts utilized are members of the salmon family that become parasitized during the freshwater portion of their life cycle. After infection, the metacercariae are found to develop predominantly within the kidneys and muscles of the fish. The metacercariae are capable of persisting in the tissues of the fish for almost two years after they return to the sea, and after this period are capable of transmitting the causative agent of salmon poisoning disease to dogs. Mammals and birds become infected when they ingest raw salmon. The flukes mature into adults with eggs in 6 to 10 days after the fish has been eaten.</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;"> Lesions in cats infected with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>salmincola</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> have not been described. Hoeppli (1926) examined the damage to the intestinal mucosa of the dog induced by this parasite and believed it to be highly pathogenic; however, Hoeppli’s studies were performed before the discovery of the rickettsial cause of this disease.</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;"> Probably praziquantel, but not reported.</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;"> Cats become infected by eating raw fish. In the wilds of Oregon, many other hosts are infected (Schlegel</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;">., 1968). The most important hosts in the wild are probably the raccoon, coyote, lynx, spotted skunk, and even birds (e.g., the hooded merganser).</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;"> The rickettsia can be lethal to dogs that have ingested fish containing the rickettsial bearing trematode. If infected with the trematode, cats need to be treated to prevent the parasite from being able to complete its life cycle.</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;"> Human beings have been found infected with this parasite in Siberia. It is also possible that the rickettsial agent may cause disease in human beings. People, like cats, obtain their infections by the ingestion of raw fish. </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;"> The prevention of the ingestion of raw fish.</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;">Chapin EA. 1926. A new genus and species of trematode, the probable cause of salmon-poisoning in dogs. N Am Vet 7:36-37.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Chapin EA. 1928. Note. J Parasitol 14:60.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Donham CR, Simms BT, Miller FW. 1926. So-called salmon poisoning in dogs. Progress report. JAVMA 71:215-217.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Hoeppli R. 1926. Anatomische veranderungen des Hundarms, hervorgerufen durch Nanophyes salmincola Chapin. Arch Schiffs Tropen-Hyg 30:396-399.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Schlegel MW, Knapp SE, Millemann RE. 1968. "Salmon poisoning” disease. V. Definitive hosts of the trematode vector, Nanophyetus salmincola. J Parasitol 54:770-774.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>Figure 2-31. </b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Nanophyetus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>salmincola</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> from the small intestine of an experimentally infected cat collected in Washington D.C. in the 1920's. Note the two very large suckers and the large ovaries that are present on both sides of the body.</span></span></p>