Objective:To evaluate the predatory potential of the Odonata nymph on freshwater snails that serve as intermediate hosts for Schistosoma species(Bulinus truncatus and Biomphalaria alexandrina).Methods:Observations on ...Objective:To evaluate the predatory potential of the Odonata nymph on freshwater snails that serve as intermediate hosts for Schistosoma species(Bulinus truncatus and Biomphalaria alexandrina).Methods:Observations on the searching,attacking and devouring of the two snail types with series of laboratory-based predation experiments,whose aims were to determine daily predation rate,differential predation,prey preference considering small-,mediumand large-sized snails were conducted.Results:Laboratory evaluation revealed that,the Odonata nymph could kill and consume the two intermediate hosts.The number of snails consumed differed according to the snail type,size and density.The times taken for searching and handling times were dependent on the snail size,type and satiation of the predator.The predation rate varied also with respect to snail type,size and density.This study also evaluated that Odonata nymphs consumed more Bulinus truncatus than Biomphalaria alexandrina per unit time,and that there may be a preference for smaller than larger snails.Conclusions:According to our observation,the predator,Hemianax ephippiger nymph may be a suitable biocontrol agent in connection with Schistosoma intermediate hosts.展开更多
Background The rodentia and lagomorpha animals are the intermediate hosts of Echinococcus multilocularis, their distribution and infection of this parasite may facilitate the infection of definitive hosts such as dogs...Background The rodentia and lagomorpha animals are the intermediate hosts of Echinococcus multilocularis, their distribution and infection of this parasite may facilitate the infection of definitive hosts such as dogs. The aim of this study was to determine the distribution of the intermediate hosts of Echinococcus multilocularis in Shiqu County, Sichuan, China. Methods A systematic sampling method was used to investigate the density of burrows of rodents and lagomorphs at 97 pasture sites in winter and summer pastureland and remote sensing （RS） techno（ogy was used to correlate their densities to the distribution of these animals in different landscape types. Results Based on the densities of Ochotona curzoniae, Microtus fuscus （dependent variable） and their burrow densities （independent variable） in survey points, regression equations were fitted respectively （Ochotona curzoniae, P 〈0.0001, R2=0.8705; Microtus fuscus, P 〈0.0001,R2=0.9736）. Their burrow density in summer pastureland was higher than in winter pastureiand （F=36.65, P 〈0.0001）. The burrow densities of Ochotona curzoniae and Microtus fuscus in bareland and half-bareland are higher than in grassland （F=7.73, P〈0.001）. Conclusions The regression relationship between the densities of Ochotona curzoniae and Microtus fuscus and their burrow densities indicate that the burrow densities could reflect the animal densities and that the burrow density was greater in summer pastureland than in winter pastureland. The main distribution areas of the intermediate hosts were in bareland and half-bareland.展开更多
Background:Angiostrongyliasis is a food-borne parasitic zoonosis.Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis.The life cycle of A.cantonensis involves rodents as de...Background:Angiostrongyliasis is a food-borne parasitic zoonosis.Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis.The life cycle of A.cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts.This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts,which are key components in the strategy for the prevention and control of angiostrongyliasis.Methods:Three villages from Nanao Island,Guangdong Province,China,were chosen as study area by stratified random sampling.The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016,with spatial correlations of the positive P.canaliculata and the infection rates analysed by ArcGIS,scan statistics,ordinary least squares(OLS)and geographically weighted regression(GWR)models.Results:A total of 2192 P.canaliculata specimens were collected from the field,of which 1190 were randomly chosen to be examined for third-stage larvae of A.cantonensis.Seventy-two Angiostrongylus-infected snails were found,which represents a larval infection rate of 6.1%(72/1190).In total,110 rats including 85 Rattus norvegicus,10 R.flavipectus,one R.losea and 14 Suncus murinus were captured,and 32 individuals were positive(for adult worms),representing an infection rate of 29.1%of the definitive hosts(32/110).Worms were only found in R.norvegicus and R.flavipectus,representing a prevalence of 36.5%(31/85)and 10%(1/10),respectively in these species,but none in R.losea and S.murinus,despite testing as many as 32 of the latter species.Statistically,spatial correlation and spatial clusters in the spatial distribution of positive P.canaliculata and positive rats existed.Most of the spatial variability of the host infection rates came from spatial autocorrelation.Nine spatial clusters with respect to positive P.canaliculata were identified,but only two correlated to infection rates.The results show that corrected Akaike information criterion,R2,R2 adjusted andσ2 in the GWR model were superior to those in the OLS model.Conclusions:P.canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts,demonstrating that there was a risk of angiostrongyliasis in this region of China.The distribution of positive P.canaliculata and rats exhibited spatial correlation,and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A.cantonensis.展开更多
Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on m...Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on mor-phological and/or genomic criteria,which have their limitations.These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach.Recently,Matrix-Assisted Laser Desorp-tion/lonization Time-Of-Flight(MALDI-TOF)mass spectrometry,a new tool used which is routinely in clinical microbi-ology,has emerged in the field of malacology for the identification of freshwater snails.This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskali snail populations according to their geographicalorigin.Methods This study was conducted on 101 Bi.pfeifferi and 81 Bu.forskali snails collected in three distinct geo-graphical areas of Senegal(the North-East,South-East and central part of the country),and supplemented with wild and laboratory strains.Specimens which had previously been morphologically described were identified by MALDl-TOF MS[identification log score values(LSV)≥1.7],after an initial blind test using the pre-existing database.After DNA-based identification,new reference spectra of Bi.pfeiferi(n=10)and Bu.forskali(n=5)from the geographical areas were added to the MALDI-TOF spectral database.The final blind test against this updated database was per-formed to assess identification at the geographic source level.Results MALDI-TOF MS correctly identified 92.1%of 101 Bi.pfeifferi snails and 98.8%of 81 Bu.forskali snails.At the final blind test,88%of 166 specimens were correctly identified according to both their species and sampling site,with LSVs ranging from 1.74 to 2.70.The geographical source was adequately identified in 90.1%of 91 Bi.pfeifferi and 85.3%of 75 Bu.forskalii samples.Conclusions Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin.It outperforms the current DNA-based approaches in discriminating laboratory from wild strains.This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.展开更多
Background Gastropoda,the largest class within the phylum Mollusca,houses diverse gut microbiota,and some gastropods serve as intermediate hosts for parasites.Studies have revealed that gut bacteria in gastropods are ...Background Gastropoda,the largest class within the phylum Mollusca,houses diverse gut microbiota,and some gastropods serve as intermediate hosts for parasites.Studies have revealed that gut bacteria in gastropods are associated with various biological aspects,such as growth,immunity and host-parasite interactions.Here,we summarize our current knowledge of gastropod gut microbiomes and highlight future research priorities and perspectives.Methods A literature search was undertaken using PubMed,Web of Science and CNKI for the articles on the gut microbiota of gastropods until December 31,2022.We retrieved a total of 166 articles and identified 73 eligible articles for inclusion in this review based on the inclusion and exclusion criteria.Results Our analysis encompassed freshwater,seawater and land snails,with a specific focus on parasite-transmitting gastropods.We found that most studies on gastropod gut microbiota have primarily utilized 16S rRNA gene sequencing to analyze microbial composition,rather than employing metagenomic,metatranscriptomic,or metabolomic approaches.This comprehensive review provided an overview of the parasites carried by snail species in the context of gut microbiota studies.We presented the gut microbial trends,a comprehensive summary of the diversity and composition,influencing factors,and potential functions of gastropod gut microbiota.Additionally,we discussed the potential applications,research gaps and future perspectives of gut microbiomes in parasite-transmitting gastropods.Furthermore,several strategies for enhancing our comprehension of gut microbiomes in snails were also discussed.Conclusions This review comprehensively summarizes the current knowledge on the composition,potential function,influencing factors,potential applications,limitations,and challenges of gut microbiomes in gastropods,with a specific emphasis on parasite-transmitting gastropods.These findings provide important insights for future studies aiming to understand the potential role of gastropod gut microbiota in controlling snail populations and snail-borne diseases.展开更多
Background:Food-borne parasitic diseases decrease food safety and threaten public health.The snail species is an intermediate host for numerous human parasitic trematodes.Orientogalba ollula has been reported as inter...Background:Food-borne parasitic diseases decrease food safety and threaten public health.The snail species is an intermediate host for numerous human parasitic trematodes.Orientogalba ollula has been reported as intermediate hosts of many zoonotic trematodes.Here,we investigated the prevalence of zoonotic trematodes withinO.ollula in Guangxi,China,and assessed their zoonotic potential.Methods:Snails were collected from 54 sites in 9 cities throughout Guangxi.The snail and trematode larvae species were determined by combining morphological characteristics and molecular markers.The trematodes prevalence and constituent ratio were calculated and compared among different habitat environments.Phylogenetic trees of the trematode species were constructed using the neighbor-joining method with nuclear internal transcribed spacer 2(ITS2)sequences.The developmental cycles of the isolated trematodes were examined by experimental infection in ducks.The developmental characteristics ofEchinostoma revolutum was recorded by dissecting infected ducklings from 1-day post infection(dpi)to 10 dpi.Results:The overall prevalence of trematode larvae was 22.1%(1818/8238)inO.ollula from 11 sample sites.Morphological together with molecular identification,showed thatE.revolutum,Australapatemon sp.,Hypoderaeum conoideum,Pharyngostomum cordatum,andEchinostoma sp.parasitizedO.ollula,with the highest infection rate ofE.revolutum(13.0%).However,noFasciola larvae were detected.The trematodes prevalence and constituent ratio varied in two sub-biotypes(P<0.01).A neighbor-joining tree analysis of ITS2 sequences resulted in distinct monophyletic clades supported by sequences from isolated larvae with high bootstrap values.Ducklings exposed toO.ollula infected withEchinostoma sp.,E.revolutum,andH.conoideum larvae were successfully infected.The animal model forEchinostoma revolutum was successfully established.E.revolutum matured from larvae to adult at 10 dpi in the intestine of the duck,and the developmental characteristics ofE.revolutum were characterized by the maturation of the reproductive and digestive organs at 6-8 dpi.Conclusions:This study revealed a high prevalence of zoonotic trematodes inO.ollula from Guangxi,China.Existing trematodes infection in animals and human clinical cases,coupled with the wide geographical distribution ofO.ollula,necessitate further evaluations of the potential risk of spillover of zoonotic infection from animal to human and vice versa.展开更多
Background:The construction and operation of small multipurpose dams in Africa have a history of altering the transmission of water-based diseases,including schistosomiasis.The current study was designed to investigat...Background:The construction and operation of small multipurpose dams in Africa have a history of altering the transmission of water-based diseases,including schistosomiasis.The current study was designed to investigate the abundance and dynamics of schistosomiasis intermediate host snails and Schistosoma infections in humans during the construction and the first years of operation of a small multipurpose dam in Côte d’Ivoire.Methods:The study was carried out in Raffierkro and four neighbouring villages in central Côte d’Ivoire between 2007 and 2012.Snails were collected by two experienced investigators using scoops and forceps for 15 min at each site.Snails were identified at genera and,whenever possible,species level,and subjected to testing for cercarial shedding.Schoolchildren aged 6-15 years were examined once every year for Schistosoma haematobium and S.mansoni infection,using urine filtration and duplication Kato-Katz thick smears,respectively.Additionally,551 adults were examined for Schistosoma infection before(June 2007)and 359 individuals 2 years after dam construction(June 2009).Results:Overall,1700 snails belonging to nine different genera were collected from 19 sampling sites.Bulinus(potential intermediate host snails of S.haematobium)and Pila were the most common genera,whereas Biomphalaria(potential intermediate host snail of S.mansoni),Lymnaea,Physa and Melanoides were found in two villages.During the first-year sampling period,65 snails were collected,of which 13(20%)were schistosomiasis intermediate hosts.In subsequent years,out of 1635 snails collected,1079(66%)were identified as potential intermediate host for schistosomiasis,but none were shedding cercariae.The prevalence of S.mansoni among adults in the study area was low(0.4%in 2007 and 0.3%in 2009),whereas the prevalence of S.haematobium declined from 13.9%to 2.9%in this two-year period.Conclusions:The low prevalence of schistosomiasis in humans and the absence of infected intermediate host snails during the construction and early phase of operation of a small multipurpose dam suggest that there was no or only very little local transmission.However,the considerable increase in the number of intermediate host snails and their dispersion in irrigation canals call for rigorous surveillance,so that adequate public health measures can be taken in case of early signs of an outbreak.展开更多
基金Supported by Theodor Bilharz Research Institute,Imbaba,Giza,Egypt(Grant No.94M)
文摘Objective:To evaluate the predatory potential of the Odonata nymph on freshwater snails that serve as intermediate hosts for Schistosoma species(Bulinus truncatus and Biomphalaria alexandrina).Methods:Observations on the searching,attacking and devouring of the two snail types with series of laboratory-based predation experiments,whose aims were to determine daily predation rate,differential predation,prey preference considering small-,mediumand large-sized snails were conducted.Results:Laboratory evaluation revealed that,the Odonata nymph could kill and consume the two intermediate hosts.The number of snails consumed differed according to the snail type,size and density.The times taken for searching and handling times were dependent on the snail size,type and satiation of the predator.The predation rate varied also with respect to snail type,size and density.This study also evaluated that Odonata nymphs consumed more Bulinus truncatus than Biomphalaria alexandrina per unit time,and that there may be a preference for smaller than larger snails.Conclusions:According to our observation,the predator,Hemianax ephippiger nymph may be a suitable biocontrol agent in connection with Schistosoma intermediate hosts.
文摘Background The rodentia and lagomorpha animals are the intermediate hosts of Echinococcus multilocularis, their distribution and infection of this parasite may facilitate the infection of definitive hosts such as dogs. The aim of this study was to determine the distribution of the intermediate hosts of Echinococcus multilocularis in Shiqu County, Sichuan, China. Methods A systematic sampling method was used to investigate the density of burrows of rodents and lagomorphs at 97 pasture sites in winter and summer pastureland and remote sensing （RS） techno（ogy was used to correlate their densities to the distribution of these animals in different landscape types. Results Based on the densities of Ochotona curzoniae, Microtus fuscus （dependent variable） and their burrow densities （independent variable） in survey points, regression equations were fitted respectively （Ochotona curzoniae, P 〈0.0001, R2=0.8705; Microtus fuscus, P 〈0.0001,R2=0.9736）. Their burrow density in summer pastureland was higher than in winter pastureiand （F=36.65, P 〈0.0001）. The burrow densities of Ochotona curzoniae and Microtus fuscus in bareland and half-bareland are higher than in grassland （F=7.73, P〈0.001）. Conclusions The regression relationship between the densities of Ochotona curzoniae and Microtus fuscus and their burrow densities indicate that the burrow densities could reflect the animal densities and that the burrow density was greater in summer pastureland than in winter pastureland. The main distribution areas of the intermediate hosts were in bareland and half-bareland.
基金This study was funded by The Special Foundation of Basic Science and Technology Resources Survey of Ministry of Science and Technology of China(No.2017FY101203)the National Key Research and Development Program of China(No.2016YFC1202000,2016YFC1202001)the National Science and Technology Major Project of China(No.2012ZX1004–220,2008ZX1004–011).
文摘Background:Angiostrongyliasis is a food-borne parasitic zoonosis.Human infection is caused by infection with the third-stage larvae of Angiostrongylus cantonensis.The life cycle of A.cantonensis involves rodents as definitive hosts and molluscs as intermediate hosts.This study aims to investigate on the infection status and characteristics of spatial distribution of these hosts,which are key components in the strategy for the prevention and control of angiostrongyliasis.Methods:Three villages from Nanao Island,Guangdong Province,China,were chosen as study area by stratified random sampling.The density and natural infection of Pomacea canaliculata and various rat species were surveyed every three months from December 2015 to September 2016,with spatial correlations of the positive P.canaliculata and the infection rates analysed by ArcGIS,scan statistics,ordinary least squares(OLS)and geographically weighted regression(GWR)models.Results:A total of 2192 P.canaliculata specimens were collected from the field,of which 1190 were randomly chosen to be examined for third-stage larvae of A.cantonensis.Seventy-two Angiostrongylus-infected snails were found,which represents a larval infection rate of 6.1%(72/1190).In total,110 rats including 85 Rattus norvegicus,10 R.flavipectus,one R.losea and 14 Suncus murinus were captured,and 32 individuals were positive(for adult worms),representing an infection rate of 29.1%of the definitive hosts(32/110).Worms were only found in R.norvegicus and R.flavipectus,representing a prevalence of 36.5%(31/85)and 10%(1/10),respectively in these species,but none in R.losea and S.murinus,despite testing as many as 32 of the latter species.Statistically,spatial correlation and spatial clusters in the spatial distribution of positive P.canaliculata and positive rats existed.Most of the spatial variability of the host infection rates came from spatial autocorrelation.Nine spatial clusters with respect to positive P.canaliculata were identified,but only two correlated to infection rates.The results show that corrected Akaike information criterion,R2,R2 adjusted andσ2 in the GWR model were superior to those in the OLS model.Conclusions:P.canaliculata and rats were widely distributed in Nanao Island and positive infection has also been found in the hosts,demonstrating that there was a risk of angiostrongyliasis in this region of China.The distribution of positive P.canaliculata and rats exhibited spatial correlation,and the GWR model had advantage over the OLS model in the spatial analysis of hosts of A.cantonensis.
文摘Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on mor-phological and/or genomic criteria,which have their limitations.These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach.Recently,Matrix-Assisted Laser Desorp-tion/lonization Time-Of-Flight(MALDI-TOF)mass spectrometry,a new tool used which is routinely in clinical microbi-ology,has emerged in the field of malacology for the identification of freshwater snails.This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskali snail populations according to their geographicalorigin.Methods This study was conducted on 101 Bi.pfeifferi and 81 Bu.forskali snails collected in three distinct geo-graphical areas of Senegal(the North-East,South-East and central part of the country),and supplemented with wild and laboratory strains.Specimens which had previously been morphologically described were identified by MALDl-TOF MS[identification log score values(LSV)≥1.7],after an initial blind test using the pre-existing database.After DNA-based identification,new reference spectra of Bi.pfeiferi(n=10)and Bu.forskali(n=5)from the geographical areas were added to the MALDI-TOF spectral database.The final blind test against this updated database was per-formed to assess identification at the geographic source level.Results MALDI-TOF MS correctly identified 92.1%of 101 Bi.pfeifferi snails and 98.8%of 81 Bu.forskali snails.At the final blind test,88%of 166 specimens were correctly identified according to both their species and sampling site,with LSVs ranging from 1.74 to 2.70.The geographical source was adequately identified in 90.1%of 91 Bi.pfeifferi and 85.3%of 75 Bu.forskalii samples.Conclusions Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin.It outperforms the current DNA-based approaches in discriminating laboratory from wild strains.This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.
基金supported by the National Key R&D Program of China(Nos.2020YFC1200100,2020YFC1200103,2021YFC2300800 and 2016YFC1200500)the National Natural Science Foundation of China(Nos.82202560,82161160343 and 82272361)+5 种基金the R&D Program in Key Areas of Guangdong Province(No.2022B1111030002)the Fundamental Research Funds for the Central University(No.22qntd4813)the Science and Technology Planning Project of Guangdong Province(No.2021B1212040017)the 111 Project(No.B12003)the 6th Nuclear Energy R&D Project(No.20201192)the National Parasitic Resource Center and Ministry of Science and Technology(No.NPRC-2019-194-30).
文摘Background Gastropoda,the largest class within the phylum Mollusca,houses diverse gut microbiota,and some gastropods serve as intermediate hosts for parasites.Studies have revealed that gut bacteria in gastropods are associated with various biological aspects,such as growth,immunity and host-parasite interactions.Here,we summarize our current knowledge of gastropod gut microbiomes and highlight future research priorities and perspectives.Methods A literature search was undertaken using PubMed,Web of Science and CNKI for the articles on the gut microbiota of gastropods until December 31,2022.We retrieved a total of 166 articles and identified 73 eligible articles for inclusion in this review based on the inclusion and exclusion criteria.Results Our analysis encompassed freshwater,seawater and land snails,with a specific focus on parasite-transmitting gastropods.We found that most studies on gastropod gut microbiota have primarily utilized 16S rRNA gene sequencing to analyze microbial composition,rather than employing metagenomic,metatranscriptomic,or metabolomic approaches.This comprehensive review provided an overview of the parasites carried by snail species in the context of gut microbiota studies.We presented the gut microbial trends,a comprehensive summary of the diversity and composition,influencing factors,and potential functions of gastropod gut microbiota.Additionally,we discussed the potential applications,research gaps and future perspectives of gut microbiomes in parasite-transmitting gastropods.Furthermore,several strategies for enhancing our comprehension of gut microbiomes in snails were also discussed.Conclusions This review comprehensively summarizes the current knowledge on the composition,potential function,influencing factors,potential applications,limitations,and challenges of gut microbiomes in gastropods,with a specific emphasis on parasite-transmitting gastropods.These findings provide important insights for future studies aiming to understand the potential role of gastropod gut microbiota in controlling snail populations and snail-borne diseases.
基金Guangxi Traditional Chinese Medical University Scientific Research Project(XP021059)National Parasitic Resources Center(NPRC-2019-194-30)Key Technology Project of Inner Mongolia Science and Technology Department(2021GG0171)。
文摘Background:Food-borne parasitic diseases decrease food safety and threaten public health.The snail species is an intermediate host for numerous human parasitic trematodes.Orientogalba ollula has been reported as intermediate hosts of many zoonotic trematodes.Here,we investigated the prevalence of zoonotic trematodes withinO.ollula in Guangxi,China,and assessed their zoonotic potential.Methods:Snails were collected from 54 sites in 9 cities throughout Guangxi.The snail and trematode larvae species were determined by combining morphological characteristics and molecular markers.The trematodes prevalence and constituent ratio were calculated and compared among different habitat environments.Phylogenetic trees of the trematode species were constructed using the neighbor-joining method with nuclear internal transcribed spacer 2(ITS2)sequences.The developmental cycles of the isolated trematodes were examined by experimental infection in ducks.The developmental characteristics ofEchinostoma revolutum was recorded by dissecting infected ducklings from 1-day post infection(dpi)to 10 dpi.Results:The overall prevalence of trematode larvae was 22.1%(1818/8238)inO.ollula from 11 sample sites.Morphological together with molecular identification,showed thatE.revolutum,Australapatemon sp.,Hypoderaeum conoideum,Pharyngostomum cordatum,andEchinostoma sp.parasitizedO.ollula,with the highest infection rate ofE.revolutum(13.0%).However,noFasciola larvae were detected.The trematodes prevalence and constituent ratio varied in two sub-biotypes(P<0.01).A neighbor-joining tree analysis of ITS2 sequences resulted in distinct monophyletic clades supported by sequences from isolated larvae with high bootstrap values.Ducklings exposed toO.ollula infected withEchinostoma sp.,E.revolutum,andH.conoideum larvae were successfully infected.The animal model forEchinostoma revolutum was successfully established.E.revolutum matured from larvae to adult at 10 dpi in the intestine of the duck,and the developmental characteristics ofE.revolutum were characterized by the maturation of the reproductive and digestive organs at 6-8 dpi.Conclusions:This study revealed a high prevalence of zoonotic trematodes inO.ollula from Guangxi,China.Existing trematodes infection in animals and human clinical cases,coupled with the wide geographical distribution ofO.ollula,necessitate further evaluations of the potential risk of spillover of zoonotic infection from animal to human and vice versa.
基金This study was financially supported by the Swiss-based non-governmental organization FAIRMED(Bern,Switzerland).
文摘Background:The construction and operation of small multipurpose dams in Africa have a history of altering the transmission of water-based diseases,including schistosomiasis.The current study was designed to investigate the abundance and dynamics of schistosomiasis intermediate host snails and Schistosoma infections in humans during the construction and the first years of operation of a small multipurpose dam in Côte d’Ivoire.Methods:The study was carried out in Raffierkro and four neighbouring villages in central Côte d’Ivoire between 2007 and 2012.Snails were collected by two experienced investigators using scoops and forceps for 15 min at each site.Snails were identified at genera and,whenever possible,species level,and subjected to testing for cercarial shedding.Schoolchildren aged 6-15 years were examined once every year for Schistosoma haematobium and S.mansoni infection,using urine filtration and duplication Kato-Katz thick smears,respectively.Additionally,551 adults were examined for Schistosoma infection before(June 2007)and 359 individuals 2 years after dam construction(June 2009).Results:Overall,1700 snails belonging to nine different genera were collected from 19 sampling sites.Bulinus(potential intermediate host snails of S.haematobium)and Pila were the most common genera,whereas Biomphalaria(potential intermediate host snail of S.mansoni),Lymnaea,Physa and Melanoides were found in two villages.During the first-year sampling period,65 snails were collected,of which 13(20%)were schistosomiasis intermediate hosts.In subsequent years,out of 1635 snails collected,1079(66%)were identified as potential intermediate host for schistosomiasis,but none were shedding cercariae.The prevalence of S.mansoni among adults in the study area was low(0.4%in 2007 and 0.3%in 2009),whereas the prevalence of S.haematobium declined from 13.9%to 2.9%in this two-year period.Conclusions:The low prevalence of schistosomiasis in humans and the absence of infected intermediate host snails during the construction and early phase of operation of a small multipurpose dam suggest that there was no or only very little local transmission.However,the considerable increase in the number of intermediate host snails and their dispersion in irrigation canals call for rigorous surveillance,so that adequate public health measures can be taken in case of early signs of an outbreak.
