• Parasites, Hosts and Diseases
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• 제56권3호
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• pp.247-257
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• 2018

The aim of this study was to conduct a freshwater snail survey in Mae Lao agricultural basin to assess the diversity with a focus on habitat types and their larval trematode infections. Snails were collected and examined in 14 sites of Mae Lao agricultural basin from August 2016 to October 2017. A total of 1,688 snail individuals were collected and classified into 7 families, 8 genera, and 12 species. Snail diversity and habitat types were higher in rice paddies than irrigation canals and streams. The most abundant species was Bithynia siamensis siamensis, representing 54.6% of the sample. Three species of snails act as first intermediate host were found with cercarial infections. They were Filopaludina sumatrensis polygramma, B. s. siamensis, and Melanoides tuberculata. The cercariae were categorized into 7 types; echinostome, monostome, gymnocephalous, virgulate, parapleurolophocercous, pleurolophocercous and megalurous cercariae. Parapleurolophocercous cercariae constituted the most common type of cercariae recovered, contributing 41.2% of all infections in snails. Echinostome metacercariae infections were found in 6 snail species with 7.6% prevalence. In addition, the metacercaria of avian trematode, Thapariella sp. were found in Filopaludina spp. snails and B. funiculata with a prevalence of 0.5%. This is the first report for Thapariella metacercariae in the snail host, B. funiculata, and also confirmed that viviparid and bithyniid snails act as the second intermediate hosts of this trematode. This work will provide new information on the distribution and intermediate host of trematode in this area.

• Parasites, Hosts and Diseases
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• 제58권2호
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• pp.205-210
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• 2020

Echinococcosis occurs mainly in areas with heavy livestock farming, such as Central Asia, America, and Australia. Echinococcus granulosus sensu lato (s.l.) infection causes echinococcosis in intermediate hosts, such as sheep, cattle, goats, camels, and horses. Numerous cases of echinococcosis occur in Uzbekistan as stock farming is a primary industry. Epidemiological and genetic studies of E. granulosus s.l. are very important for mitigating its impact on public health and the economy; however, there are no such studies on E. granulosus s.l. in Uzbekistan. In the present study, to determine which genotypes exist and are transmitted, we isolated Echinococcus sp. from definitive hosts (one isolate each from jackal and dog) and intermediate hosts (52 isolates from humans and 6 isolates from sheep) in Uzbekistan and analyzed the isolates by sequencing 2 mitochondrial DNA components (cox1 and nad1). The results showed that all of isolates except one belonged to the E. granulosus sensu stricto (s.s.) G1 and G3 genotypes. Phylogenetic analysis based on cox1 sequences showed that 42 isolates from humans, 6 isolates from sheep, and one isolate from jackal were the G1 genotype, whereas the remaining 8 isolates from human and the one isolate from dog were the G3 genotype. These results suggest that the G1 and G3 genotypes of E. granulosus s.s. are predominant in Uzbekistan, and both wild animals and domestic animals are important for maintaining their life cycle. Only one isolate from human sample was confirmed to be E. eqiinus (G4 genotype), which is known to be for the first time.

• 한국패류학회지
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• 제28권1호
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• pp.13-19
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• 2012

본 연구는 한국산 연체동물의 감염 병원체의 실태와 한반도 기후변화에 따른 질병의 변화를 예측하기 위해 연구 보고된 문헌을 고찰하였다. 야생동물은 인체에 기생하는 인수공통전염병 기생충에 대한 중간숙주, 보유숙주 및 연체숙주로 제공되고 있다. 흡충류는 연체동물의 흔한 기생충이며 거의 모든 흡충류는 그들의 생활사에서 1차숙주로서 패류에 감염되며, 대부분은 또 다른 숙주를 포함하는 복잡한 생활사를 가지고 있다. 지금까지 기생충의 생태학에 대한 보조숙주로서의 중요성은 논의된 바 없다. 최근에 기후변화의 관점에서 많은 기생성 질병이 역학적 관심이 증가되고 있다. 한국산 연체동물을 대상으로 연구 보고된 문헌을 중심으로 기생성 병원체를 가진 종들을 조사 한 결과 전체 21종의 패류가 매개 기생체를 가지며, 이들 패류 21종이 가지고 있는 병원체는 모두 39종류로 확인되었다. 이 중 담수패류가 15종 그리고 해산패류에서 6종으로 나타났다. 담수패류 중 다슬기과의 다슬기 (Semisulcospira livertina) 에서 페흡충, 요코가와흡충, 가시입이형흡충 등 가장 많은 11종류의 기생성 병원체를 가지는 것으로 조사되었고, 쇠우렁이 (Parafossarulus manchouricus) 에서는 간흡충, 동양배반흡충, 메기장흡충, 오리오목흡충, 일본극구흡충 등 11종류, 다슬기류 (Semisulcospira sp.) 에서는 폐흡충, 요코가와흡충, 가시입이형흡충 등 10종류, 염주알다슬기(Koreanomelania globus) 에서는 메기소식흡충 등 7종류, 바지락 (Tapes philippinarum) 에서는 Cercariae tapidis 등 3 종류 그리고 나머지 패류에서 1-2 종류의 기생성 병원체를 보유하는 것으로 나타났다. 특히 앞으로 홍수나 가뭄과 같은 극심한 기후변화가 일어난다면 담수패류는 기생성 매개자로서의 매우 중요한 역할을 할 것으로 예측되었다.

• Parasites, Hosts and Diseases
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• 제52권6호
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• pp.645-652
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• 2014

Fasciola hepatica is a trematode that causes zoonosis mainly in cattle and sheep and occasionally in humans. Fascioliasis has been reported in Korea; however, determining F. hepatica infection in snails has not been done recently. Thus, using PCR, we evaluated the prevalence of F. hepatica infection in snails at 4 large water-dropwort fields. Among 349 examined snails, F. hepatica-specific internal transcribed space 1 (ITS-1) and/or ITS-2 markers were detected in 12 snails and confirmed using sequence analysis. Morphologically, 213 of 349 collected snails were dextral shelled, which is the same aperture as the lymnaeid snail, the vectorial host for F. hepatica. Among the 12 F. hepatica-infected snails, 6 were known first intermediate hosts in Korea (Lymnaea viridis and L. ollula) and the remaining 6 (Lymnaea sp.) were potentially a new first intermediate host in Korea. It has been shown that the overall prevalence of the snails contaminated with F. hepatica in water-dropwort fields was 3.4%; however, the prevalence varied among the fields. This is the first study to estimate the prevalence of F. hepatica infection using the vectorial capacity of the snails in Korea.

• Parasites, Hosts and Diseases
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• 제51권6호
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• pp.633-636
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• 2013

Angiostrongylus cantonensis is a parasitic nematode that needs to develop in different hosts in different larval stages. Freshwater snails, such as Pomacea canaliculata, are the intermediate host, and rats are the definitive host. Periodic shedding of the cuticle (moulting) is an important biological process for the survival and development of the parasite in the intermediate and definitive hosts. However, there are few studies on the cuticle alterations between different stages of this parasite. In this study, we observed the ultrastructural appearance and changes of the cuticle of the 2nd/3rd stage larvae (L2/L3) and the 3rd/4th stage larvae (L3/L4) using a scanning electron microscope. We also first divided L2/L3 into late L2 and early L3. The late L2 lacked alae, but possessed a pull-chain-like fissure. Irregular alignment of spherical particles on the cuticle were noted compared to the L3. Alae appeared in the early L3. The old cuticle turned into a thin filmlike structure which adhered to the new cuticle, and spherical particles were seen regularly arranged on the surface of this structure. Regular rectangular cavities were found on the surface of L3/L4. The caudal structure of L3/L4 was much larger than that of L3, but caudal inflation, such as seen in L4, was not observed. These results are the first to reveal the ultrastructural changes of the cuticle of A. cantonensis before and after moulting of L2/L3 and L3/L4.

• Parasites, Hosts and Diseases
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• 제26권3호
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• pp.207-214
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• 1988

강원도 홍천군내를 임류하여 경기도 청평댐으로 유입되는 홍천강 유역 주민의 Metagonimus속 흡충 감염실태와 홍천강에 서식하는 중간숙주의 감염상을 조사하였다. 홍천강 유역 주민의 Metngonimus속 흡충 감염률은 529명(남 314, 여 215)중 39명(남 33명, 10.5%; 여 6명, 2.8%)으로 평균 7.4%의 양성률을 보였다. 총 8개 지점에 대한 조사중 북방면 굴흑이가 주민감엽률 26.9% (남자는 38.2%)로 가장 높았고 제 1중간숙주인 다슬기의 서식밀도도 높았다(m2당10∼20개). 다슬기의 Metagonimus 유미유충 감염률은 10.7%(121개중 13개)였다. 주민들의 호생식성 어종이며 근단. 수가 많은 피라미 (Zncco platypus)의 metacercaria 감염은 68.2%(44마리중 30마리)이며 주 검출부위는 비늘(89.9%)이었다. 피라미에서 검출된 metacercaria를 흰쥐에 감염시킨 다음 15일후에 성충을 회수하고, 사람에서 검출한 충체와 비교하였던 바 동일종으로 관찰되었다. 검출된 충체는 Metagcnimus takahashis([고교]흡충)와 기타 Metagonimus속 흡충이 혼재해 있었다. 이상의 결과로 강원도 홍천강 유역에 Metagonimus 흡충 감염이 높은 지역이 있음을 알았고 주요 감염원이 되는 어종은 피라미임을 알 수 있었다.

• Parasites, Hosts and Diseases
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• 제59권2호
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• pp.121-129
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• 2021

We aimed to explore the population dynamics of snail in 3 sites of the White Nile in Sudan. More specifically, we aimed to investigate the annual patterns of snail populations that act as intermediate hosts of schistosomes and monthly snail infection rates and ecological characteristics presumably related to snail populations. We collected snails for 1 year monthly at 3 different shore sites in the vicinity of El Shajara along the White Nile river in Khartoum State, Sudan. In addition, we measured air and water temperatures, water turbidities, vegetation coverages, and water depths and current speeds. Most of the collected snails were Biomphalaria pfeifferi and Bulinus truncatus. The population densities of snails and their infection rates varied across survey sites. The collected snails liberated S. mansoni and S. haematobium cercariae as well as Amphistome and Echinostome cercariae. Infected snails were found during March-June. The ecological characteristics found to be associated with the absence of snails population were: high turbidity, deep water, low vegetation coverage (near absence of vegetation), high water temperature, and high current speed. To our knowledge, this is the first longitudinal study of the snail population and ecological characteristics in the main basin of the White Nile river.

• Parasites, Hosts and Diseases
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• 제62권1호
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• pp.85-97
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• 2024

This study aimed to describe the morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae isolated in Thailand. Adult flukes were isolated from the Chinese pipistrelle bat (Hypsugo sp.), and cercariae were detected in the viviparid snail (Filopaludina martensi martensi) from Chiang Mai province. The morphological characteristics were observed and described using conventional methods, and the molecular characteristics with internal transcribed spacer 2 (ITS2) and 28S rDNA gene sequences. The adult flukes were fusiform, 0.84-0.98 mm in length, and 0.37-0.49 mm in width, and were distinguishable from other species by the presence of longitudinal uterine coils. The cercariae were nonvirgulate xiphidiocercariae, with the oral sucker bigger than the acetabulum, the tail without fin fold, a body size of 117.5-138.3×48.3-52.2 ㎛, and a tail size of 100.7-103.7×15.0-18.9 ㎛. Molecular studies revealed that the adults and cercariae shared 99.3% (ITS2) and 99.6% (28S rDNA) homology with each other. They were phylogenetically close to P. longiforme with an identity of 94.5% for ITS2 and 98.7% for 28S rDNA. This study provides new information on the natural definitive host and first intermediate host of P. longiforme in Thailand. The discovery of its cercarial stage in Filopaludina snails highlights the importance of monitoring the associated second intermediate host and prevention and control of this potentially zoonotic trematode.

• Parasites, Hosts and Diseases
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• 제51권6호
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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.

• 한국임상수의학회지
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• 제25권4호
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• pp.307-309
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• 2008

The metacercariae species have often been isolated from fresh water fish in Korea. In this study, we reported Clinostomum complanatum, a species of metacercariae isolated from gill and muscle of Korean barbel (Hemibarbus mylodon), a natural monument fresh water fish in Korea, by morphological observation. The excysted metacercariae, tongue-shaped and progenetic, were 3.11-4.62 mm in length and 0.90-1.43 mm in width. Fresh water fishes are known as the second intermediate hosts of C. complanatum. This is the first isolation report from Korean barbel.