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Asian Pacific Journal of Tropical Medicine 2017年第2期10卷 120-126页

作者： Phornphitcha Pechdee Monticha Chaiyasaeng Chanisala Sereewong Jukkrid Chaiyos Apiporn Suwannatrai Sutee Wongmaneeprateep Smarn Tesana Food-Borne Parasite Research Group Department of ParasitologyFaculty of MedicineKhon Kaen University Department of Fisheries Faculty of AgricultureKhon Kaen University

Objective:To explore larvicidal effects of anthelmintic drugs on Opisthorchis viverrini(***) for alternative approach to interrupting its cycle for developing a field-based control ***:The larvicidal activities of albendazole(A1),artesunate(Ar),praziquantel(Pzq) and miltefosine(Mf) on *** cercariae and mature metacercariae were *** concentrations(LC_(50) and LC_(95)) of these drugs were *** metacercariae previously exposed to various concentrations of the drugs were administered to *** were harvested 30 d post infection and worm recovery rates ***,Ar,Pzq and Mf produced morphological degeneration and induced shedding tails of cercariae after 24 h ***:The LC_(50) and LC_(95) of Al,Ar,Pzq and Mf on cercariae were 0.720 and 1.139,0.350 and 0.861,0.017 and 0.693,and 0.530 and 1.134 ppm,***_(50) and LC_(95) of Ar on mature metacercariae were 303.643 and 446.237 ppm and of Mf were 289.711 and 631.781 ppm,respectively but no lethal effect in Pzq-and Al-treated groups(up to 1 ppt).No worms were found in hamsters administered Pzq-treated *** adult worms from Al-treated metacercariae were significantly bigger in size compared to the control group(Pcercariae compared to the control group(Pcercariae but lesser efficacy to *** should be further studied with the eventual aim of developing a field-based control program.

关键词： Albendazole Artesunate Praziquantel Miltefosine Opisthorchis viverrini cercariae

AUTORADIOGRAPHIC STUDY OF THE ATTRITION OF MIGRATING SCHISTOSOMULA IN THE SKIN OF MICE *** CHALLENGED WITH NORMAL *** cercariae AFTER IMMUNIZATION WITH HIGHLY IRRADIATED cercariae

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Chinese Medical Sciences Journal 1990年第1期8卷 30-36页

作者： S.Y.Li Hsu H.F.Hsu J.W.Osborne W.R.Clarke C.K.Hawk Y.Ohnishi College of Medicine University of IowaIowaUSA

The migratory pattern and attrition of75Se-labelled *** challenge cercariae in CF1mice immunized 0,1,3, or 5 times with 12kR-or 48kR-irradiated cercariae were investigatedby compressed organ *** were percutaneously inoculated with 500-1000 cer-cariae for each immunization and with a known count of approximately 90 cercariae at adifferent site for *** skin,lungs,liver,other organs,and catrcass were processedfor *** and mesenteric perfusions for worm collection were alsosampled from day 19 through *** naive tnice,25% of challenge cercariae died in *** attrition of challenge cercariae in mice immunized with 12kR-irradiated cercariaewas 43% with 1 immunization,54% with 3,and 58% with 5,whereas in mice immunized with48kR-irradiated cercariae,skin,attrition was48% with 1,63% with 3,and 76% with 5 *** all immunized mice,a high percentage of migrating sehistosomula died in the skinwithin 24 hours of a challenge *** autoradiography,it was found that thesilver foci created by single labelled worms were difficult to differentiate from those of *** study documents the induction of acquired resistance against a challenge infectionin the skin by vaccination with highly irradiated cercariae,with the degree of attemtation ofimmunizing cercariae and the number of immunizations being closely related to the *** in the ***,we discuss the contradictory views concerning the site of attritiotn ofchallenge cercariae.

关键词： autoradiography attrition—challenge cercariae immunization—highly X-irradiated cercariae Schistosoma mansoni

Characterization of randomly amplified polymorphic DNA (RAPD) fragments revealing clonal variability in cercariae of avian schistosome <i>Trichobilharzia szidati</i>(Trematoda: Schistosomatidae)

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Open Journal of Genetics 2013年第3期3卷 141-158页

作者： Anna Korsunenko Galina Chrisanfova Alexander Arifov Alexey Ryskov Seraphima Semyenova Institute of Gene Biology Russian Academy of Sciences Moscow Russia

Recently we applied randomly amplified polymorphic DNA (RAPD) fingerprinting to detect clonal variability among individual cercariae within daughter sporocysts and rediae of 10 digenean trematodes (Platyhelminthes: Trematoda). The most variable RAPD patterns were obtained for Schistosomatidae representative-avian schistosome Trichobilharzia szidati. In this work, 50 polymorphic DNA fragments of approximately 300-1500 bp from RAPD patterns of individual T. szidati cercariae were cloned and sequenced. As a result genomic DNA sequences (total length of approximately 41,000 bp) revealing clonal variability in T. szidati cercariae were obtained and analyzed. The analysis indicated that these sequences contained tandem, inverted and dispersed repeats as well as regions homological to retroelements of two human parasites, Schistosoma mansoni and S. japonicum. Tandem and inverted repeats constituted 8.9% and 22.1% respectively, while the percentage of dispersed repeats was 21.0%. The average content of these components was 41.7% with the average AT content being 59.0%. About 40% of sequences included regions ranging in length from 96 to 1005 bp which displayed amino acid homology with open reading frame pol products of S. mansoni and S. japonicum retroelements: non-long terminal repeat retrotransposons (nLTRs, 76%), long terminal repeat retrotransposons (LTRs, 14%), and Penelope-like elements (PLEs, 10%). Most of these regions (86.4%) contained frameshifts, gaps, and stop-codons. The largest portion of them was homological to nLTRs of the RTE clade (67%). The number of sequences homologous to the members of CR1 lineage was 7 times smaller (9%). Homology with LTRs of Gypsy/Ty3 and BEL clades was revealed in 5% and 9% of cases respectively. We assume that the repetitive elements including retroelement-like sequences described in the current study may serve as the source of clonal variability detected previously in T. szidati and other digenean trematodes. Such genome regions

关键词： RAPD Variability cercariae Heterogeneity Trichobilharzia szidati Repetitive DNA

Effects of vertical position on trematode parasitism in larval anurans

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Current Zoology 2019年第6期65卷 657-664页

作者： Jacob R.JONES Camille L.STEENROD John A.MARINO Jr. Biology Department Bradley UniversityPeoriaILUSA Department of Geography University of MarylandCollege ParkMDUSA

Spatial distributions of animals can affect interactions with their natural enemies,such as parasites,and thus have important implications for host-parasite *** spatial variation in infection risk has been explored in many systems at the landscape scale,less attention has been paid to spatial structure at smaller ***,we explore a hypothesized relationship between a common spatial variable,vertical position,and risk of parasite infection in a model aquatic system,larval frogs(Rana)and trematode(Digenea)*** position is relevant to this system given evidence that the densities of snail first intermediate hosts,tadpole second intermediate hosts,and trematode infective stages can vary with *** test the effects of depth on infection risk of larval frogs by trematodes,we performed two enclosure experiments,one in the laboratory and one in the field,in which larval frogs in cages just below the water surface or near the bottom of the water column were exposed to *** with near-surface cages,mean infection load(number of cysts)in tadpoles in near-bottom cages was 83%higher after 48-h exposures in the laboratory and 730%higher after 10-day exposures in the *** findings thus indicate that infection risk depends on depth,which may have adaptive significance,as tadpoles have previously been shown to change vertical position in response to parasite *** results motivate future work examining vertical variation in infection risk and may have broader implications for host-parasite dynamics and evolution of host and parasite behavior.

关键词： avoidance behavior cercariae Echinostomatidae host-parasite interactions Rana spatial structure

Do algae blooms dilute the risk of trematode infections in threespine sticklebacks？

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Current Zoology 2015年第6期61卷 991-995页

作者： Alexandre BUDRIA Ulrika CANDOLIN Department of Biosciences University of Helsinki EO. Box 65 FI-00014 Helsinki Finland

Human-induced growth of macro-algae is often assumed to increase trematode infections in fishes by increasing the abtmdanee and condition of the parasite＇s intermediate host - snails - as this can boost the release of trematode larvae, cercariae, from the intermediate hosts. However, macro-algae can also impose barriers to the transmission of cercariae and reduce infections. We investigated whether an increased growth of filamentous algae affects the transmission of Diplostomum pseudospathaceum cercariae to the threespine stickleback Gasterosteus aculeatus, a common fish in eutrophied shallow waters. We exposed stickle- backs to trematode cercariae in the absence and presence of artificial filamentous algae, and recorded effects on the proportion of sticklebacks infected and the number of encysted metacercariae per fish. No significant effect of artificial algae on cercariae transmission was detected. However, the body size and the sex of the sticklebacks were strongly correlated with the number of encysted metacercariae per infected fish, with females and larger individuals being more infected. We discuss different factors that could have caused the difference in parasite transmission, including sex-related differences in body size and behaviour of sticklebacks .

关键词： Anthropogenic disturbance cercariae Dilution effect Diplostomum pseudospathaceum Eutrophication Filament-ous algae Parasites Physical interference

A novel and effective hyperthermia method for Schistosomiasis japonica prevention and treatment

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Science Bulletin 2015年第16期60卷 1461-1464页

作者： Huixia Yang Tao Tang Pei He Youren Zhang Le Xie Guangqi Liu Li Li Weichao Kong Jingdingsha Li Ruiting Liu Yukun Li Junjian Hu Xiaowen Wang Liya Li Guanghong Xiang Geoffrey Gobert Yuesheng Li Jintian Tang The Yuquan Hospital Tsinghua University Laboratory of Innovative Medical Technology Department of Engineering Physics Tsinghua University The WHO Collaborating Centre for Research and Control of Schistosomiasis on Lake Region Hunan Institute of Parasitic Diseases Department of Pharmaceutics Beijing University of Chinese Medicine Graduate School Hunan University of Chinese Medicine School of Measuring and Optical Engineering Nanchang Hangkong University Department of Oncology Xiangya Hospital Central South University Department of Medical Oncology China-Japan Friendship Hospital Queensland Institute of Medical Research Clinic for Vascular and Endovascular Surgery University Clinic of Muenster

The emerging resistance to schistosoma has been paid much attention and is in urgent need for a novel strategy to control the prevalent parasitic zoonosis. In this study, the efficiency of hyperthermia therapy was investigated by the skin hyperthermia device. The survival rate of cercariae decreased from 68.15 % （37 ℃, 5 min） to 0 （49℃, 10 min） with the thermal dosages increased, which proved the preventing effect of hyperthermia therapy （P 〈 0.05）. Therapeutic effects were assessed in Schistosoma japonicum-infected BALB/c mice. When the cercarial contact region of the skin was treated at 45-49℃ for 5 min within 8 h of infection, worm reduction rate （WRR） reached 74 %-83 % （P 〈 0.01）. The sensitivity of adult schistosoma to heat was also investigated using microwave intraperitoneal hyperthermia （thermal dosages 42-43℃, 20 min）. The WRR, hepatic shift rates and egg reduction rates were 23.7 %, 40 % and 30 %, respectively, comparing with 80.2 %, 59.6 % and 53.9 % of praziquantel （PZQ）-treated group. Encouraging results have been obtained that hyperthermia can effectively kill schistosomula, especially with the appearance of cercarial dermatitis, while PZQ lacks efficacy against the cercariae. Thus, hyperthermia therapy would show significant benefit in preventing and treatment of schistosoma, especially in the early stage.

关键词： Hyperthermia Schistosomiasis japonica Praziquantel (PZQ) cercariae

Epidemiology of cercarial stage of trematodes in freshwater snails from Chiang Mai province,Thailand

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Asian Pacific Journal of Tropical Biomedicine 2013年第3期3卷 237-243页

作者： Thapana Chontananarth Chalobol Wongsawad Applied Parasitology Research Laboratory Department of BiologyFaculty of ScienceChiang Mai University Applied Technology in Biodiversity Research Unit Institute for Science and Technology ResearchChiang Mai University

Objective:To investigate the epidemiological situation of cercarial trematodes infection in freshwater snails from different water resources in Chiang Mai province,***:The snail specimens were collected from 13 districts of Chiang Mai province during April 2008 to February *** prevalence of cercarial infection in snails was investigated using the crushing *** drawing was done with the help of a camera lucida for the morphological ***:A total of 2479 snail individuals were collected and classified into 7 families,11 genera,and 14 species,Among them,8 snails species were found to be infected with an overall prevalence of 17.27%(428/2479),which infected with nine groups of cercariae;gymnocephalous cercaria,strigea cercaria,megalurous cercaria,monostome cercaria,parapleurolophocercous cercaria(Haplorchis cercaria),pleurolophocercous cercaria,furcocercous cercaria(Transversotrema cercaria),xiphidiocercaria,and virgulate *** parapleurolophocercous cercaria was found to be the dominant type among the cercarial infection in the snails(64.25%).Conclusions:The various species of snails found in the research location act as the intermediate hosts for the high prevalence of parasitic infection of many species of *** work will provide new information on both the distribution and first intermediate host of trematodes.

关键词： Chiang Mai Trematodes cercariae Pleurolophocercous Prevalence Freshwater snails

Effect of temperature on the—system

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贫困所致传染病（英文） 2017年第3期 35-41页

Background: Given that increase in temperature may alter host-parasite relationships, the anticipated rise in temperature due to global warming might change transmission patterns of certain diseases. However, the extent to which this will happen is not well ***: Using a host-parasite system involvingBulinus globosus andSchistosoma haematobium, we assessed the effect of temperature on snail fecundity, growth, survival and parasite development under laboratory ***: Our results show that temperature may have a non-linear effect on snail fecundity and snail growth. Snails maintained at 15.5 °C and 36.0 °C did not produce egg masses while those maintained at 25.8 °C laid 344 and 105more egg masses than snails at 31.0 °C and 21.2 °C, respectively. Attainment of patency led to a reduction in egg mass production among the snails. However, the reduction in fecundity for snails maintained at 21.2 °C occurred before snails started shedding cercariae. Parasite development was accelerated at high temperatures with snails maintained at 31.0 °C reaching patency after three weeks. Furthermore, snail growth rate was highest at 25.8 °C while it was inhibited at 15.5 °C and reduced at 31.0 °C. Increase in temperature increased snail mortality rates. Snails maintained at 36.0 °C had the shortest survival time while those maintained at 15.5 °C had the longest survival ***: We concluded that temperature influences fecunxdity, growth, survival and parasite development in the snail and thus dictates the time it takes the parasite to complete the life cycle. This has implications on transmission of schistosomiasis in the context of global warming.

关键词： Bulinus globosus cercariae Development rate Fecundity Schistosomiasis Schistosoma haematobium Temperature

<i>Schistosoma mansoni</i>: Phytochemical Effect on Aquatic Life Cycle

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Open Journal of Veterinary Medicine 2015年第6期5卷 127-132页

作者： Ronaldo de Carvalho Augusto Gabriela Friani Maurício Carvalho de Vasconcellos Maria de Lurdes de Azevedo Rodrigues Clélia Christina Mello-Silva Laboratório de Avaliaç ã o e Promoç ã o da Saúde Ambiental Instituto Oswaldo Cruz Funda&ccedil ã o Oswaldo Cruz Rio de Janeiro Brasil Departamento de Parasitologia Animal Curso de Pós-Gradua&ccedil ã o em Ciências Veterinárias Universidade Federal Rural do Rio de Janeiro Seropédica Brasil

Background: Two aspects need to be considered for schistosomiasis control: morbidity and transmission. In this context, many soluble substances have been tested and Euphorbia milii latex is one of the most promising Brazilian molluscicides. Phytochemical studies involving simulation of the applicability of this latex on all aquatic forms of the S. mansoni life cycle are rare in the literature. The aim of this work was to evaluate the effect of E. milii latex on S. mansoni in the egg, miracidium and different developmental stages in Biomphalaria glabrata. Methods: The laboratory study was designed to simulate the different forms of exposure of the life cycle stages of S. mansoni to the LC50 of E. milii latex;we tested the exposition from four situations of S. mansoni contact with the latex and observed the exposure on different snails’ infection stage too. All snails were analyzed weekly for cercarial shedding and reproductive biology. Results: The results showed that contact of S. mansoni eggs and miracidia with the LC50 of E. milii negatively influenced the development of the parasite life cycle in the intermediate host, with consequent reduction of cercarial shedding. The exposure of infected snails affected the reproductive biology and cercarial shedding in all intra-mollusk development stages of S. mansoni, but the reduction was greater in the first, fourth, fifth, sixth, seventh and eighth weeks of infection. The LC50 of E. milii latex had toxic action on eggs and miracidia, and the number of cercariae shed by snails during the study period declined by about 80%. Conclusions: We can conclude that the use of natural biodegradable compounds containing low concentrations of substances already characterized as having eco-toxico- logical potential can be an important tool to reduce the transmission of Schistosomiasis.

关键词： Schistosomiasis cercariae Miracidia Eggs Euphorbia milii

Larval stages of digenetic trematodes in Melanopsis praemorsa snails from freshwater bodies in Palestine

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Asian Pacific Journal of Tropical Biomedicine 2011年第3期1卷 200-204页

作者： Sami Bdir Ghaleb Adwan Department of Biology and Biotechnology

Objective:To detect the species of larval trematodes(cercariae) in Melanopsis praemorsa snails from 5 different fresh water bodies in ***:A total of 1 880 Melanopsis praemona snails were collected from different fresh water bodies in Palestine from October,2008 to November,*** in Melanopsis praemona snails were obtained by lighting and crushing *** behavior of cercariae was observed using a dissecting ***:Three different species of larval trematodes were identified from Melanopsis praemona snails collected only from Al-Bathan fresh water body,while snails from other water bodies were not infected. These species were microcercous cercaria,xiphidiocercaria and brevifurcate lophocercous *** cercariae called Cercaria melanopsi palestinia 1,Cercaria melanopsi palestinia H and Cercaria melanopsi palestinia III have not been described before from this snail in Palestine. The infection rate of Melanopsis praemona collected from Al-Bathan fresh water body was 5.7%, while the overall infection rate of snails collected from all fresh water bodies was 4.3%.Details are presented on the morphology and behavior of the cercariae as well as their development within the ***:These results have been recorded for the first time and these cercariae may be of medical and veterinary importance.

关键词： Melanopsis praemorsa Digenetic trematodes cercariae Xiphidiocercaria Brevifurcate lophocercous Microcercous Palestine Larval trematode