Metagonimus yokogawai

Metagonimus yokogawai

<p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><i><b>Metagonimus yokogawai</b></i></span></span><span style="color: #000000;"><span style="font-size: large;"><b> (Katsurada, 1912) Katsurada, 1912</b></span></span></p> <p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><b>(Figure 2-27)</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>gonimus</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>yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> = for Dr. Yokogawa.</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>Heterophyes yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Katsurada, 1912; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Loxotrema ovatum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Kobayashi, 1912; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metagonimus ovatus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Yokogawa, 1913; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Loossia romanica</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Ciurea, 1915; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Loossia parva </i></span></span><span style="color: #000000;"><span style="font-size: medium;">Ciurea, 1915; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Loossia dobrogiensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Ciurea, 1915.</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 fluke was originally described as </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Heterophyes yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> by Katsurada, but later, the same author renamed the worm </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metagonimus yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The original description was based on material obtained by Dr. Yokogawa from human beings and from experimentally infected cats and dogs in Taiwan.</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 is the most common heterophyid trematode in the Far East. It has also been reported from Siberia, the Balkans, and from human beings in Spain.</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>Metagonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> can be identified by the position of the ventral sucker and genital opening which are fused and displaced to the right of the midline of the body. The testes are close together at the posterior of the body where one is slightly anteriad to the other. The ventral sucker is larger than the oral sucker. The adults of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metagonimus yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are 1 to 1.5 mm long with eggs that are 26 to 28 µ by 15 to 17 µm.</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, like that of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Heterophyes heterophyes</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, does not hatch upon contact with water, but rather, only after it is infected by the appropriate fresh-water snail, e.g., </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Semisulcospira libertina</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The cercariae that are produced have long tails with thin dorso-ventral tail fins. The cercariae infect fish between the scales, and metacercariae develop predominantly within the muscles. Fresh-water fish that have been shown to be intermediate hosts include </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Plectoglossus altivelis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Odontobutis obscurus</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Salmo perryi</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>Tribolodon hakonensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Animals become infected when they ingest the raw flesh of these fishes.</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;"> Shallow ulcers may be present in the mucosa of the jejunum where parasites live within the villus epithelium. There is a shortening of the villus length and adhesions formed between villi. During the first 5 to 15 days after infection, there is a decrease in the number of goblet cells present in the areas around the trematodes; this number then returns to normal levels (Kim</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). Heavy infestations are likely to cause small bowel diarrhea.</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.</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. Other hosts that ingest infected raw fish are also likely to become infected.</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 an be infected through the ingestion of infected raw fish; however, due to the requirements for two intermediate hosts, it is unlikely that an infected cat would pose a direct threat to other animals.</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 infected with this parasite on numerous occasions and are the host from which the parasite was first recovered. 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;">Kim BW, Lee JB, Cho SY. 1983. Attitude of goblet cells in small intestine of experimental cat metagonimiasis. Chung-Ang J Med 8:243-251.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Rho IH, Kim SI, Kang SY, Cho SY. 1984. Observation on the pathogenesis of villous changes in early phase of experimental metagonimiasis. Chung-Ang J Med 9:67-77.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>Figure 2-27.</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Metagonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>yokogawai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> collected from a dog in Japan in 1919 by Dr. Yokogawa. Note the paired testes in the posterior of the body. The displace genito-acetabulum is difficult to observe in this figure.</span></span></p>