1990 Fiscal Year Final Research Report Summary
Geographical distribution and host specificity of the two lung fluke species parasitizing the freshwater crab, Geothelphusa dehaani
| Project/Area Number |
63570173
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
寄生虫学(含医用動物学）
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| Research Institution | Hamamatsu University School of Medicine |
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Principal Investigator |
KINO Hideto Hamamatsu University School of Medicine, Department of Parasitology, Research Associate, 医学部, 助手 (70115476)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Geothelphusa dehaani / Paragonimus westermani / Paragonimus miyazakii / Sympatric distribution / Host specificity / Snail host / Ovary morphology |
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| Research Abstract |
1) Digestion, homogenizing and pressing methods for collecting metacercariae from crabs were compared. As a result, successive use of pressing and homogenizing methods provided the highest efficiency.
2) Pick-up, quadrat and trap methods for sampling crabs were compared in respect of infection levels of the crab population. It was concluded that the quadrat method should be employed to estimate infection parameters, and parameters from crabs larger than a threshold size should be taken to comparewith those in other localities.
3) Lung flukes are widely distributed in the western Shizuoka Prefecture and around Shinshiro-city, Aichi Prefecture, though at a low level. No infected crabs were found in northern area to Shinshiro-city. Infection level of wild mammals were very low.
4) Paragonimus westermani and P. miyazakii coexist in the same crab population at Mikkabi-cho, Shizuoka Prefecture. Although morphology of the ovary of P. westermani resembled that of P. miyazakii in pressed speciment
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s, a protein analysis revealed clear difference between the two. The first intermediate host snail of P. westermani was found on the study site, although snail host for P. miyazakii was not found. This suggests that distribution of host snails could be an important factor for the coexistence of the two species. Sympatric distribution by closely related species with the same ecological niche would be worth investigating further.
5) In experimental infection of dogs and rats, 16% of recovered worms were P. westermani. Those in rats were often found in the plural cavity. Most individuals of different species did not share the same cyst, remaining species independency.
6) To clarify morphological difference in the ovary of the two species, three-dimensional reconstruction technique was employed. In P. westermani, although branching structure was variable, all individuals examined had a common basic structure consisting of 6 lobes. In P. miyazakii the structure was complicated, suggesting a fundamental difference between the two species. Less
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