• Applied Microscopy
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• v.27 no.4
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• pp.403-416
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• 1997

In order to observe the localization of the specific antigenic protein in the tissue of Paragonimus westermani metacercaria, immunogoldlabeling method was applied using IgG of the dog which were infected with Paragonimus westermani metacercaria and IgG of rabbits which were immunized with purified 23 kDa protein from metacercaria of the Paragenimus westermani. The metacercaria worm tissues obtained from Cambaroides similis were embedded in Lowicryl HM20 medium, treated with infected and immunized IgG and protein A gold complex (particle size; 12 nm) and observed by electron microscope. In the tissue antigen of Paragonimus westermani metacercaria, the content of excretory bladder which was highly dense electron density was constituted in the excretory bladder of the parenchymal tissue. In the metacercaria tissues antigen reacted with IgG of infected dog. Labeled gold particles distributed on the interstitial matrix of parenchymal cells, fibrous granules of parenchymal tissue and the content of excretory bladder. High antigenicity was observed on content of excretory bladder. It was found to be specifically distributed at the tissue of Paragonimus westermani metacercaria. In the tissues antigen reacted with IgG of immunized rabbit. Labeled gold particles randomly distributed on the interstitial matrix and fibrous granules of parenchymal tissue but in the content of excretory bladder of Paragonimus westermani metacercaria, gold particles were richly labeled. Therefore, the 23 kDa protein contained with Paragonimus westermani metacercaria was found protein which was specifically constituted at the content of excretory bladder of Paragonimum westermani metacercaria. The 23 kDa protein was commonly contained from of Paragonimus westermani metacercaria to adult and showed strong antigenicity against the immunized and infected IgG.

• Parasites, Hosts and Diseases
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• v.51 no.6
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• pp.621-627
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• 2013

Paragonimiasis is a food-borne parasitic zoonosis caused by infection with lung flukes of the genus Paragonimus. In Vietnam, research on Paragonimus and paragonimiasis has been conducted in northern and central regions of the country. Using a combination of morphological and molecular methods, 7 Paragonimus species, namely P. heterotremus, P. westermani, P. skrjabini, P. vietnamensis, P. proliferus, P. bangkokenis, and P. harinasutai, have been identified in Vietnam. Of these, the first 3, P. heterotremus, P. westermani, and P. skrjabini, are known to infect humans in other countries. However, in Vietnam, only P. heterotremus, found in some northern provinces, has been shown to infect humans. Even nowadays, local people in some northern provinces, such as Lai Chau and Yen Bai, are still suffering from P. heterotremus infection. In some provinces of central Vietnam, the prevalence and infection intensity of P. westermani metacercariae in freshwater crabs (the second intermediate hosts) are extremely high, but human cases have not been reported. Likewise, although P. skrjabini was found in Thanh Hoa Province, its pathogenicity to humans in Vietnam still remains uncertain. The results of molecular phylogenetic analyses of Vietnamese Paragonimus species provides new insights on the phylogeny and taxonomy of the genus Paragonimus. Comprehensive molecular epidemiological and geobiological studies on the genus in Vietnam and adjacent countries are needed to clarify the biodiversity and public health significance of the lung flukes.

• Parasites, Hosts and Diseases
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• v.37 no.1
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• pp.55-57
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• 1999

During the period from October 1996 to November 1998, the infection status of Paragonimus westermani metacercariae in freshwater crayfish (Cambaroides similis) collected from Bogildo (islet), Wando-gun, Chollanam-do, which is known for an endemic area of P. westermani in Korea, were examined. The average infection rate of Paragonimus metacercariae in crayfish was 88.6%, and mean number of metacercariae per infected crayfish was 30.2. This metacercarial density was the highest in the group of weight in 7.1-9.0 g. These results suggest that the natural life cycle of P. westermani is still well-preserved in Bogildo.

• Parasites, Hosts and Diseases
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• v.29 no.1
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• pp.43-54
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• 1991

An in vitro immune effector mechanism against the target encysted metacercariae of Paragonimus westermani was demonstrated in the rat system. Peritoneal exudate cells, mainly macrophages from normal rats, showed adherence to and killing of encysted metacercariae of p. westermani in the presence of complement-independent serum from rats infected with Paragonimus metacercariae. These reactions were specific for the excysted metacercariae, as tissue-migrating juvenile worms were not affected. Damage of encysted metacercariae of p. westermani due to antibody and macrophages was assessed by morphological observation, by cell adherence reaction and by the use of vital dyes. frypan blue dye exclusion proved to be a reliable indicator of judging metacercarial viability. Electron microscopic studies demonstrated that macrophages reacted with fusty material on the tegumental surface and fine structures in the syncytium of the parasites. The tubular tunnels formed between the basement membrane and muscle layers of the damaged parasites were also noticeable. The relevance of these findings to cellular immunity in the early paragonimiasis was discussed.

• Parasites, Hosts and Diseases
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• v.41 no.1
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• pp.47-55
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• 2003

We compared patterns of intraspecific polymorphism of two markers with contrasting modes of evolution, nuclear ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA), in the lung fluke, diploid and triploid Paragonimus westermani from three geographical regions of Korea. The genetic distances between three populations of Korean diploid and triploid P. westermani showed no significant difference in the nucleotide sequences of the mitochondrial cytochrome c oxidase subunit 1 (mtCOI) and ribosomaal second internal transcribed spacer (ITS2) genes. A highly resolved strict-consensus tree was obtained that illustrated phylogenetically useful information of the ITS2 and mtCOI sequences from diploid and triploid P. westermani.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.102-110
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• 1985

In order to determine the epidemiological pattern of the Paragonimus westermani, the infestation rates for the cercarial and metacer-carial larvae of digenetic trematodes in the snail and crayfish hosts, and the prevalence of Paragonimus westermani among the residents in the vicinity of the stream Namdae, Wyangpi, and Kwang, in the Ulchin county, Kyungpook Province were studied from March to October in 1984. The population density of the snails per square meter of the habitats ranged from 5 to 25, with an average of 15. Among the seven habitats, one, Ducheon, had snails infested with the cercariae of Paragonimus westermani, and the proportion of infested snails was very low, the average being 0.152 per thousand. Of six hundred and four crayfish examined, 113 or 18.7 per cent harboured the encysted larvae of Paragonimus westermani. A high infestation rate for the metacercariae in the crayfish was found in two habitats; 39.0 per cent in the Ducheon and 21. 6 per cent m the Sokwang. The prevalence of Paragonimus westermani among the residents in Ulchin county was relatively high, 25.8 per cent by the Paragonimus intradermal tests, and the difference in the rate of infection between males and females was found to be significant (t>2). The results obtained in this study indicate that endemic foci of Paragonimus westermani exist in Ulchin county and the prevalence of this lung fluke among the residents is relatively high.

• Parasites, Hosts and Diseases
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• v.40 no.2
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• pp.89-92
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• 2002

The cysteine proteases of Paragonimus westermani metacercariae are involved in metacercarial excystment, host immune modulation, and possibly in tissue penetration. In order to clarify the origin of the enzymes, 28 and 27 kDa cysteine proteases in metacercarial excretory-secretory products were purified through the FPLC system using Mono Q column chromatography. The polyclonal antibodies to the enzymes were produced in BALB/c mice. Immunolocalization studies revealed that both cysteine proteases were distributed at the linings of excretory bladder and excretory concretions of the metacercariae. It was suggested that the excretory epithelium of P. westermani undertake the secretory function of metacercarial cysteine proteases, in addition to its role as a route for eliminating waste products.

• Parasites, Hosts and Diseases
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• v.41 no.4
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• pp.221-231
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• 2003

To gain information on retrotransposons in the genome of Paragonimus westermani, PCR was carried out with degenerate primers, specific to protease and reverse transcriptase (rt) genes of long-terminal-repeat (LTR) retrotransposons. The PCR products were cloned and sequenced, after which 12 different retrotransposon-related sequences were isolated from the trematode genome. These showed various degrees of identity to the polyprotein of divergent retrotransposon families. A phylogenetic analysis demonstrated that these sequences could be classified into three different families of LTR retrotransposons, namely, Xena, Bel, and Gypsy families. Of these, two mRNA transcripts were detected by reverse transcriptase-PCR, showing that these two elements preserved their mobile activities. The genomic distributions of these two sequences were found to be highly repetitive. These results suggest that there are diverse retrotransposons including the ancient Xena family in the genome of P. westermani, which may have been involved in the evolution of the host genome.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.19-23
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• 1985

Collections of Semisulcospira snails and crayfishes were made to detect out larval trematodes in Bogil Islet, Wando-Gun, Chonra-Nam-Do, Korea in August, 1985. In addition, intradermal test to figure out the prevalence rate of paragonimiasis in the islanders was also carried out. The results are summarized as follows: 1) Nineteen out of 186 examinees(10.2%) showed positive reactions by intradermal test with Paragonimus antigen. 2) Forty four snails out of 182 snails collected were infected with trematode cercariae. These larvae were Metagonimus sp., Cercaria yoshidae, Cercaria incerta and Cercarianipponensis. 3) Metacercarial incidence of Paragonimus westermani in crayfish was 65.4%. Mean number of metacercariae per crayfish was 6.5.

• Parasites, Hosts and Diseases
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• v.43 no.1 s.133
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• pp.33-37
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• 2005

Eosinophil degranulation is considered to be a key effector function for the killing of helminthic worms and tissue inflammation at worm-infected lesion sites. However, relatively little data are available with regard to eosinophil response after stimulation with worm-secreted products which contain a large quantity of cysteine proteases. In this study, we attempted to determine whether the degranulation of human eosinophils could be induced by the direct stimulation of the excretory-secretory products (ESP) of Paragonimus westermani, which causes pulmonary paragonimiasis in human beings. Incubation of eosinophils for 3 hr with Paragonimus-secreted products resulted in marked degranulation, as evidenced by the release of eosinophil-derived neurotoxin (EON) in the culture supernatants. Moreover, superoxide anion was produced by eosinophils after stimulation of the ESP. The ESP-induced EDN release was found to be significantly inhibited when the ESP was pretreated with protease inhibitor cocktail or the cysteine protease inhibitor, E-64. These findings suggest that human eosinophils become degranulated in response to P. westermani-secreted proteases, which may contribute to in vivo tissue inflammation around the worms.