Paragonimus westermani

Paragonimus westermani

<p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><i><b>Paragonimus westermani</b></i></span></span><span style="color: #000000;"><span style="font-size: large;"><b> (Kerbert, 1878) Braun, 1899</b></span></span></p> <p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><b>(Figure 2-42)</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>Para</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> = side-by-side 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;"> = gonads along with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>westerman </i></span></span><span style="color: #000000;"><span style="font-size: medium;">= for Dr. Westerman the curator of the Zoo in Amsterdam who submitted the original specimens to Dr. Kerbert for identification.</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 westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Kerbert, 1878; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma ringeri</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Cobbold, 1880; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma pulmonum</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Baelz, 1881; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma pulmonis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Kiyona, 1881; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Mesogonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Railliet, 1890; </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Polysarcus westermanni</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Lühe, 1899.</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;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> was described as </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> for specimens that were recovered from Indian tigers that died in zoos in Amsterdam and Hamburg. At the same time parasites were observed by Drs. Manson, Ringer, and Cobbold that were described as a new species </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Distoma ringeri</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Braun in 1899 created the genus </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in which he placed </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</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>GEOGRAPHIC DISTRIBUTION:</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> is found in southeastern Siberia, Japan and Korea through China, Taiwan, and the Philippines, through Indonesia, Malaysia, and Thailand, and into India and Sri Lanka. </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;"> In cysts in the lungs.</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;"> Species of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus </i></span></span><span style="color: #000000;"><span style="font-size: medium;">are 7 to 12 mm long, 4 to 8 mm wide, and quite thick, i.e., 4 to 6 mm. </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> differs from other species of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in Asia in that specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus pulmonalis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> reproduce parthenogenetically and have no sperm in the seminal receptacle; specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus miyazakii</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are more slender than</span></span><span style="color: #000000;"><span style="font-size: medium;"><i> Paragonimus westermani</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>Paragonimus pulmonalis</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, have a ventral sucker that is slightly larger than the oral sucker, and have more lobes on the ovary and testis; specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus heterotremus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> have an oral sucker that is about twice the diameter of the ventral sucker (in most species they are approximately the same size); specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus skrjabini</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> tend to be more elongate with a tapered posterior end and the ventral sucker being somewhat anteriad; specimens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus ohirai</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are characterized by having the spines on the body surface appearing in groups or clusters rather than being singularly spaced.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> The eggs have a brown shell, a distinct operculum, and occasionally a knob on the abopercular end; eggs range from 70 to 100 µm in length by 39 to 55 µm in width.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> In Korea, work has been performed that has shown that ELISAs using both crude and purified antigens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> show promise for the identification of infections in cats (Lee and Chang, 1987; Choi</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;">., 1987). Specific antibody levels were significantly increased by two to three weeks after infection, and they remained elevated for up to 6 months. After treatment, specific antibody returned to baseline levels. </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 adult flukes lay eggs that are coughed up with sputum and then swallowed to be passed in the feces. After the feces enters fresh water, it takes about 2 weeks for the eggs to mature and for the miracidium to hatch. The free swimming miracidium infects a species of snail within the genera </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Brotia</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> or </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Semisulcospira</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The second intermediate hosts are fresh-water crabs (</span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Sinopotamon</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Candidiopotamon</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Sundathelphusa</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Parathelphusa</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Geohelphusa</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>Ranguna</i></span></span><span style="color: #000000;"><span style="font-size: medium;">) and crayfish (</span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Cambaroides</i></span></span><span style="color: #000000;"><span style="font-size: medium;">). The second intermediate hosts typically become infected when they eat the infected snail that harbors cercariae that are characterized by a very short tail and a pronounced stylet associated with the oral sucker. The metacercariae of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> are slightly smaller than those of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus pulmonalis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> measuring about 0.35 mm in diameter; the metacercariae are found in the gills and the muscles. When ingested, the metacercariae migrate through the intestinal wall into the abdominal cavity. After several days in the abdominal cavity, the worms migrate through the diaphragm into the lungs where they develop to adult worms, typically in pairs. Infections become patent in 65 to 90 days, and in humans, patent infections have been maintained for up to 20 years. Pigs have been shown to serve as paratenic hosts, and it is possible that other smaller rodents may also serve in this fashion. In these hosts, the young flukes are found distributed throughout the muscle tissues. </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;"> Infections in cats produce signs that are markedly less severe than infections with similar numbers of worms in human beings or other primates (Yokogawa</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;">., 1960). The young flukes appear to migrate about the abdominal cavity at random initially, causing hemorrhagic lesions in the liver and intestinal wall. Also, there are marked hemorrhagic lesions in the diaphragm, and at 20 to 30 days after infection, holes appear in the tendinous and at the edge of the muscular portions of the diaphragm that indicate the passage of larger flukes. Experimentally infected cats have died of hemorrhage into the pleural cavity. The lung parenchymal nodules that develop in cats are more clearly circumscribed than those that develop in human beings. In cats with heavy natural infections, there is extensive injury to the lung parenchyma, the pleura, and enlargement of the lymphatic tissues. The pleura becomes thickened and fibrotic and the lungs developed atelectasis and fibrosis. Eggs become widely scattered in the lung tissues and are present in the lymph nodes of the pleural cavity (Kau and Wu, 1936 [from Yokogawa,</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;">. 1960]). Cats infected with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> may also have small numbers of eggs in other tissues including the cerebrum, cerebellum, and myocardium (Shigemi, 1957 [from Yokogawa</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;">., 1960]).</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> differs from </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus pulmonalis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in that more than a single worm is required for the production of fertilized eggs. Thus, if a cat is infected with a single metacercaria of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;">, the young fluke will not mature and will often continue to migrate around in the pleural cavity laying eggs that are not capable of developing mature miracidia (Miyazaki, 1991). This might mean that cats with single worm infections are more likely to develop lesions in ectopic sites.</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;"> A cat from mainland China was treated for </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> using praziquantel. The cat was passing 11,390 eggs per gram of feces prior to treatment, it was treated with 100 mg of praziquantel per kg daily for 2 days. No eggs were detected in the feces of the cat 15 and 30 days after treatment (Cao</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;">., 1984). Experimentally infected cats have also been successfully treated with praziquantel (Choi</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;">., 1987).</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;"> Numerous mammals are capable of being infected with </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The host that harbors the largest numbers of parasites is the tiger. In a survey performed in Sumatra, Indonesia, all of 10 tigers that were examined were infected, and 1 tiger had a total of 1,596 flukes in its lungs (Kwo and Miyazaki, 1968). Other hosts that have been naturally infected include dogs, foxes, pigs, raccoon-dogs, various members of the cat family, civets, mongoose, and crab-eating macaques.</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;"> If mammals ingest the infected crab, there is a possibility that larval flukes will penetrate the intestinal wall and migrate into the abdominal cavity. In permissive hosts, the flukes will go onto develop in the lungs while in some hosts the flukes will persist as in the swine paratenic host. In all these hosts, there is the possibility for associated pathology.</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;"> Many human beings are infected with this parasite; infections are obtained by eating raw or undercooked crabs or meat of the seine paratenic host. Symptoms from the lung lesions can be severe. Similarly, the migration of worms to ectopic locations, such as the brain, can cause severe pathology. Cats are considered a major source of eggs in the environment.</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;">Cao WJ, He LY, Zhong HL, Xu ZS, Bi YC, Yu GT, Zhang QC, Li KC, Yang EV, She G, Li HJ. 1984. Paragonimiasis: Treatment with praziquantel in 40 human cases and in 1 cat. Drug Res 34:1203-1204.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Choi WY, Yoo JE, Nam HW, Choi HR. 1987. Purification of antigenic proteins of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> and their applicability to experimental cat paragonimiasis. Kor J Parasitol 24:177-186.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Kwo EH, Miyazaki I. 1968. J Parasitol 54: </span></span><span style="color: #000000;"><span style="font-size: medium;"><b>NEED REFERENCE</b></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"> Lee OR, Chang JK. 1987. ELISA of paragonimiasis in cat by crude and purified antigens of </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. Kor J Parasitol 24:187-193.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Miyazaki I. 1991. </span></span><span style="color: #000000;"><span style="font-size: medium;"><span style="text-decoration: underline;">Helminthic Zoonoses.</span></span></span><span style="color: #000000;"><span style="font-size: medium;"> 494 pages. International Medical Foundation of Japan. Fukuoka, Japan.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Yokogawa S, Cort WW, Yokogawa M. 1960. </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> and Paragonimiasis. Exp Parasitol 10:81-205.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>Figure 2-42.</b></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"><i>westermani</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> from the lung of a human.</span></span></p>