Paragonimus heterotremus

Paragonimus heterotremus

<p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><i><b>Paragonimus heterotremus</b></i></span></span><span style="color: #000000;"><span style="font-size: large;"><b> Chen and Hsia, 1964</b></span></span></p> <p align="CENTER"><span style="color: #000000;"><span style="font-size: large;"><b>(Figure 2-43)</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>heterotremus </i></span></span><span style="color: #000000;"><span style="font-size: medium;">= referring to the different sized oral and ventral suckers.</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>Paragonimus tuanshanensis</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Chung, Ho, Cheng, and Tsao, 1964 </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 first found in rats in China. That same year, another group of workers described </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Paragonimus tuanshanensis</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;"> China, Thailand, and Laos. </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 heterotremus </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 the oral sucker is larger than the ventral sucker.</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 are about 86 µm in length by 48 µm in width. </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 life cycle is basically the same as that 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;">. A snail intermediate host identified in China is </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Tricula gregoriana</i></span></span><span style="color: #000000;"><span style="font-size: medium;">. The crab hosts that are used are </span></span><span style="color: #000000;"><span style="font-size: medium;"><i>Ranguna smithiana</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>Parathelphus dugasti</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> in Thailand and </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;"> in China. The metacercariae are found in the liver, muscles, and gill of these crabs and are rather small, i.e., about 0.25 mm in diameter. </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;"> Probably similar to the 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;">. The death of a cat naturally infected with 13 of these flukes has been reported (Miyazaki and Vahrasthira, 1967).</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. </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;"> Hosts include cats, dogs, leopards, rats, and bandicoots. </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;"> Human beings have been infected with this trematode. Besides the typical pulmonary lesions, flukes have been recovered from subcutaneous tissues (Miyazaki and Harinasuta, 1966).</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;">Miyazaki I, Harinasuta T. 1966. The first case of human paragonimiasis caused by </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>heterotremus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Chen et Hsia, 1964. Ann Trop Med Parasitol 60:509-514.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;">Miyazaki I, Vajrasthira S. 1967. Occurrence of the lung fluke </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>heterotremus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> Chen et Hsiua, 1964, in Thailand. J Parasitol 53:207.</span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-size: medium;"><b>Figure 2-43.</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>heterotremus</i></span></span><span style="color: #000000;"><span style="font-size: medium;"> from the lung of a cat in Thailand. Note the large oral sucker.</span></span></p>