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1.
Parasitol Int ; 86: 102469, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34534656

RESUMO

The metacercarial infections of door snails (Gastropoda: Clausiliidae) with unknown species of the genus Brachylaima (Trematoda: Brachylaimidae) have recently been reported in eastern Honshu and Kyushu, Japan. A large scale snail survey was carried out to clarify their taxonomic status. From the period of 2015 to 2020, a total of 1239 land snails (768 door snails and 471 others) were collected from 32 localities in Honshu, Shikoku, and Kyushu. The resulting trematode isolates were identified as Brachylaima sp. by mitochondrial DNA barcoding. The sporocysts were found only a few from Megalophaedusa sublunellata (Clausiliidae), Tauphaedusa subaculus (Clausiliidae), and Aegista trochula (Camaenidae), while the metacercariae were frequently detected from 14 species of Clausiliidae and 2 species of other families. Although Brachylaima sp. showed a broad range of intermediate hosts, door snails seem to be very important to drive the life cycle. The gravid adults of Brachylaima sp. was experimentally raised from metacercariae using immunosuppressed mice. Morphological, phylogenetical, and ecological considerations prompted us to propose Brachylaima phaedusae n. sp. for this unknown species. The definitive hosts of the new species are completely unknown. The wide geographic distribution and high genetic diversity of the new species suggest a possibility that the definitive host is ground-foraging birds, which prefer door snails.


Assuntos
Caramujos/parasitologia , Trematódeos/classificação , Animais , Código de Barras de DNA Taxonômico , DNA Mitocondrial/análise , Feminino , Japão , Camundongos Endogâmicos ICR , Trematódeos/anatomia & histologia , Trematódeos/genética
2.
Infect Dis Poverty ; 10(1): 74, 2021 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-34011383

RESUMO

BACKGROUND: Oncomelania hupensis is only intermediate snail host of Schistosoma japonicum, and distribution of O. hupensis is an important indicator for the surveillance of schistosomiasis. This study explored the feasibility of a random forest algorithm weighted by spatial distance for risk prediction of schistosomiasis distribution in the Yangtze River Basin in China, with the aim to produce an improved precision reference for the national schistosomiasis control programme by reducing the number of snail survey sites without losing predictive accuracy. METHODS: The snail presence and absence records were collected from Anhui, Hunan, Hubei, Jiangxi and Jiangsu provinces in 2018. A machine learning of random forest algorithm based on a set of environmental and climatic variables was developed to predict the breeding sites of the O. hupensis intermediated snail host of S. japonicum. Different spatial sizes of a hexagonal grid system were compared to estimate the need for required snail sampling sites. The predictive accuracy related to geographic distances between snail sampling sites was estimated by calculating Kappa and the area under the curve (AUC). RESULTS: The highest accuracy (AUC = 0.889 and Kappa = 0.618) was achieved at the 5 km distance weight. The five factors with the strongest correlation to O. hupensis infestation probability were: (1) distance to lake (48.9%), (2) distance to river (36.6%), (3) isothermality (29.5%), (4) mean daily difference in temperature (28.1%), and (5) altitude (26.0%). The risk map showed that areas characterized by snail infestation were mainly located along the Yangtze River, with the highest probability in the dividing, slow-flowing river arms in the middle and lower reaches of the Yangtze River in Anhui, followed by areas near the shores of China's two main lakes, the Dongting Lake in Hunan and Hubei and the Poyang Lake in Jiangxi. CONCLUSIONS: Applying the machine learning of random forest algorithm made it feasible to precisely predict snail infestation probability, an approach that could improve the sensitivity of the Chinese schistosome surveillance system. Redesign of the snail surveillance system by spatial bias correction of O. hupensis infestation in the Yangtze River Basin to reduce the number of sites required to investigate from 2369 to 1747.


Assuntos
Rios/parasitologia , Schistosoma japonicum/isolamento & purificação , Caramujos/fisiologia , Animais , Cruzamento , China , Monitoramento Ambiental , Estudos de Viabilidade , Aprendizado de Máquina , Modelos Teóricos , Vigilância da População , Caramujos/parasitologia , Análise Espacial
3.
Parasitol Res ; 120(7): 2595-2616, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33851248

RESUMO

The presence of parasitic ciliates of the hymenostome genus Tetrahymena was examined in 150 mollusks belonging to six bivalve and 13 gastropod species in Slovakia, Central Europe. Tetrahymenids were detected only in two species, viz., in the invasive Lusitanian slug (Arion vulgaris) and in the native swollen river mussel (Unio tumidus). Although only 10.52% of the examined mollusk taxa were positive, their Tetrahymena infections were very intensive accounting for several hundreds of ciliates per host. Phylogenetic analyses of the 16S and 18S rRNA genes as well as of the barcoding region of the gene encoding for cytochrome c oxidase subunit I revealed that both isolates represent new taxa, T. foissneri sp. n. and T. unionis sp. n. The former species belongs to the 'borealis' clade and its nearest relative is T. limacis, a well-known parasite of slugs and snails. Besides molecular data, T. foissneri can be distinguished from T. limacis also morphologically by the body shape of the parasitic-phase form, dimensions of micronuclei, and the silverline system. On the other hand, T. unionis was classified within the 'paravorax' clade along with T. pennsylvaniensis, T. glochidiophila, and T. nigricans. Although these four species are genetically distinct, T. unionis could be morphologically separated only from T. nigricans by body shape and size. The present study suggests that both aquatic and terrestrial mollusks represent interesting hosts for the discovery of novel Tetrahymena lineages.


Assuntos
Bivalves/parasitologia , Caramujos/parasitologia , Tetrahymena/classificação , Animais , Cilióforos/classificação , Ciclo-Oxigenase 1/genética , Europa (Continente) , Filogenia , RNA Ribossômico 16S/genética , RNA Ribossômico 18S/genética , Alimentos Marinhos , Eslováquia , Tetrahymena/genética , Tetrahymena/crescimento & desenvolvimento
4.
J Helminthol ; 95: e22, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33875029

RESUMO

Due to the increased prevalence of human infections with bird schistosome larvae (cercarial dermatitis) associated with bathing in Danish lakes, a nationwide survey of infected intermediate host snails was conducted in 2018-2020. Pulmonate snails (10,225 specimens) were collected from 39 freshwater lakes (in the four major geographic regions in Denmark) and subjected to shedding. Released schistosome cercariae were isolated and identified by polymerase chain reaction and sequencing whereby Trichobilharzia regenti, Trichobilharzia franki, Trichobilharzia szidati and Trichobilharzia anseri were recorded. Infections were primarily determined by biotic factors such as the presence of final host birds and intermediate host snails and water temperature was noted as an important abiotic parameter associated with the infection. No clear connection with other abiotic factors (conductivity, alkalinity, pH, nitrogen, phosphorous) was seen. The widespread occurrence of infected snails, when compared to previous investigations, suggests that climate changes at northern latitudes could be responsible for the increased risk of contracting cercarial dermatitis.


Assuntos
Aves/parasitologia , Schistosomatidae , Esquistossomose , Animais , Doenças das Aves/parasitologia , Dinamarca , Lagos , Schistosomatidae/isolamento & purificação , Esquistossomose/veterinária , Caramujos/parasitologia
5.
J Comp Pathol ; 184: 31-36, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33894875

RESUMO

Calicophoron daubneyi is the primary rumen fluke (RF) found in Europe in ruminants and infection is more common in cattle than in sheep. The incidence of RF has appeared to increase greatly throughout Europe in the last 10-15 years, with outbreaks of clinical paramphistomosis confirmed in ruminants in many countries, including Great Britain and Ireland. Clinical disease, due to immature stages developing in the small intestine, appears infrequently but can occur, usually in the autumn or winter within weeks of beginning to graze wet pasture. Although disease due to adult RF has not been proven, subclinical production losses have been attributed to adult RF infection by some researchers. As the intermediate host for RF and the liver fluke (Fasciola hepatica) is the mud snail (Galba truncatula), similar habitats and environmental conditions favour both parasites. There may, however, be differences in parasite development and interactions within both the final and intermediate hosts. No anthelminthic product is licensed for treatment of ruminants for RF in the UK. However, oxyclozanide, licensed for the treatment of adult F. hepatica infection, has been shown to have activity, but it may be more effective against the adult than the immature stages. The future prevalence of RF due to climate change and limited treatment options is unpredictable. Infection and clinical disease could become more common and RF is worthy of further research.


Assuntos
Doenças dos Bovinos , Fasciolíase , Rúmen/parasitologia , Doenças dos Ovinos , Infecções por Trematódeos , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Fasciola hepatica , Fasciolíase/epidemiologia , Fasciolíase/veterinária , Paramphistomatidae , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/parasitologia , Caramujos/parasitologia , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/veterinária , Reino Unido/epidemiologia
6.
J Invertebr Pathol ; 181: 107590, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33872572

RESUMO

Oncomelania hupensis is the only obligatory intermediate host of Schistosoma japonicum, the pathogen of zoonosis schistosomiasis. Haemocytes play a critical role in the cellular immune defence of O. hupensis against S. japonicum challenge. Here, the morphology and classification of haemocytes of O. hupensis were investigated by Giemsa staining and light microscopy, combining with the scanning and transmission electron microscopy and flow cytometry. Granulocytes and hyalinocytes were confirmed as two main types of haemocytes, account for ~ 10% and ~ 90% of all haemocytes, with size varying in 4.3-10.9 µm and 0.4-30.8 µm, respectively. Subpopulations can be identified further by granule feature, shape, size, and surface and inner structure of cells. The heterogeneity in morphology implied varied developmental process and function of haemocyte subpopulations. After the S. japonicum challenge, haemocytes of O. hupensis respond to S. japonicum invasion immediately. The dynamic change of haemocyte subpopulations indicates that the small hyalinocyte could differentiate into a larger one or granulocyte after S. japonicum challenge, and the granulocytes and larger hyalinocytes play leading roles in early defence reaction, but in different ways. Phagocytosis and apoptosis of haemocytes in O. hupensis were proved to be related to immune defence against S. japonicum, with the combined effect of granulocytes and larger hyalinocytes. However, the main pathway of each subpopulation to take effect in different periods need further investigation.


Assuntos
Hemócitos/parasitologia , Schistosoma japonicum/fisiologia , Caramujos/parasitologia , Animais , Hemócitos/citologia , Hemócitos/fisiologia , Hemócitos/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Caramujos/citologia , Caramujos/fisiologia , Caramujos/ultraestrutura
7.
PLoS One ; 16(3): e0247551, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33651807

RESUMO

Host preference of symbionts evolves from fitness trade-offs. However, it is often unclear how interspecific variations in host response traits influence this evolutionary process. Using the association between the polyclad flatworm Paraprostatum echinolittorinae and its intertidal snail hosts on the Pacific Coast of Panama, we assessed how a symbiont's host preference is associated with varying host defenses and post-infestation performances. We first characterized the prevalence and intensity of worm infestation in five snail hosts (Tegula pellisserpentis, Nerita scabricosta, N. funiculata, Planaxis planicostatus, and Cerithium stercusmuscarum). We then used manipulative experiments to test flatworm's host choice, hosts' behavioral rejection of flatworms, and hosts' growth and survival following the infestation. In the field, flatworms were orders of magnitude more prevalent and dense in T. pellisserpentis, N. scabricosta, N. funiculata than P. planicostatus and C. stercusmuscarum, although the three former hosts were not necessarily more abundant. The results from our laboratory host selection trials mirrored these patterns; flatworms were 3 to 14 times more likely to choose T. pellisserpentis, N. scabricosta, N. funiculata over P. planicostatus and C. stercusmuscarum. The less preferred hosts frequently rejected flatworms via mantle contractions and foot withdrawals, which reduced the infestation rate by 39%-67%. These behaviors were less frequent or absent in the preferred hosts. Flatworm infestation variably influenced host performances in the field, negligibly affecting the growth and survival of T. pellisserpentis and N. funiculata but reducing the growth of P. planicostatus. Flatworms thus preferred less defended hosts that can also support higher worm densities without being harmed. Stable isotope analysis further revealed that flatworms are unlikely to feed on snail tissues and may live as a commensal in their preferred hosts. Our study demonstrates that host response traits can modulate a symbiont's host choice and calls for more explicit considerations of host response variability in host preference research.


Assuntos
Organismos Aquáticos/fisiologia , Infecções por Cestoides/epidemiologia , Interações Hospedeiro-Parasita/fisiologia , Platelmintos/fisiologia , Caramujos/crescimento & desenvolvimento , Caramujos/parasitologia , Simbiose/fisiologia , Animais , Evolução Biológica , Infecções por Cestoides/parasitologia , Ecossistema , Oceanos e Mares , Panamá , Fenótipo , Prevalência
8.
PLoS Negl Trop Dis ; 15(3): e0009175, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33760814

RESUMO

BACKGROUND: We were tasked by the World Health Organization (WHO) to address the following question: What techniques should be used to diagnose Schistosoma infections in snails and in the water in potential transmission sites? Our goal was to review and evaluate the available literature and provide recommendations and insights for the development of WHO's Guidelines Development Group for schistosomiasis control and elimination. METHODOLOGY: We searched several databases using strings of search terms, searched bibliographies of pertinent papers, and contacted investigators who have made contributions to this field. Our search covered from 1970 to Sept 2020. All papers were considered in a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, and retained papers were grouped by technique and subjected to our GRADE (Grading of Recommendations, Assessment, Development and Evaluations) evidence assessment profile determined in consultation with WHO. We also considered issues of sensitivity, specificity, coverage, cost, robustness, support needs, schistosome species discrimination, and relevant detection limits. PRINCIPAL FINDINGS: Our PRISMA process began with the perusal of 949 articles, of which 158 were retained for data extraction and evaluation. We identified 25 different techniques and for each applied a GRADE assessment considering limitations, inconsistency, imprecision, indirectness, and publication bias. We also provide advantages and disadvantages for each category of techniques. CONCLUSIONS: Our GRADE analysis returned an assessment of moderate quality of evidence for environmental DNA (eDNA), qPCR and LAMP (Loop-mediated isothermal amplification). No single ideal diagnostic approach has yet been developed, but considerable recent progress has been made. We note a growing trend to use eDNA techniques to permit more efficient and replicable sampling. qPCR-based protocols for follow-up detection offer a versatile, mature, sensitive, and specific platform for diagnosis though centralized facilities will be required to favor standardization. Droplet digital PCR (ddPCR) can play a complementary role if inhibitors are a concern, or more sensitivity or quantification is needed. Snail collection, followed by shedding, is encouraged to provide specimens for sequence verifications of snails or schistosomes. LAMP or other isothermal detection techniques offer the prospect of less expensive and more distributed network of analysis but may face standardization and verification challenges related to actual sequences amplified. Ability to detect schistosome infections in snails or in the water is needed if control and elimination programs hope to succeed. Any diagnostic techniques used need to be regularly verified by the acquisition of DNA sequences to confirm that the detected targets are of the expected species. Further improvements may be necessary to identify the ideal schistosome or snail sequences to target for amplification. More field testing and standardization will be essential for long-term success.


Assuntos
Schistosoma/isolamento & purificação , Caramujos/parasitologia , Água/parasitologia , Animais , DNA de Helmintos/análise , DNA Ambiental/análise , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Schistosoma/genética , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Caramujos/genética
9.
Korean J Parasitol ; 59(1): 47-53, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33684986

RESUMO

Echinostoma mekongi was reported as a new species in 2020 based on specimens collected from humans in Kratie and Takeo Province, Cambodia. In the present study, its metacercarial stage has been discovered in Filopaludina martensi cambodjensis snails purchased from a local market nearby the Tonle Sap Lake, Pursat Province, Cambodia. The metacercariae were fed orally to an experimental hamster, and adult flukes were recovered at day 20 post-infection. They were morphologically examined using light and scanning electron microscopes and molecularly analyzed by sequencing of their mitochondrial cox1 and nad1 genes. A total of 115 metacercariae (1-8 per snail) were detected in 60 (60.0%) out of 100 Filopaludina snails examined. The metacercariae were round, 174 µm in average diameter (163-190 µm in range), having a thin cyst wall, a head collar armed with 37 collar spines, and characteristic excretory granules. The adult flukes were elongated, ventrally curved, 7.3 (6.4-8.2)×1.4 (1.1-1.7) mm in size, and equipped with 37 collar spines on the head collar (dorsal spines in 2 alternating rows), being consistent with E. mekongi. In phylogenetic analyses, the adult flukes showed 99.0-100% homology based on cox1 sequences and 98.9-99.7% homology based on nad1 sequences with E. mekongi. The results evidenced that F. martensi cambodjensis snails act as the second intermediate host of E. mekongi, and hamsters can be used as a suitable experimental definitive host. As local people favor to eat undercooked snails, these snails seem to be an important source of human infection with E. mekongi in Cambodia.


Assuntos
Echinostoma/isolamento & purificação , Metacercárias/isolamento & purificação , Caramujos/parasitologia , Animais , Camboja , Echinostoma/genética , Echinostoma/crescimento & desenvolvimento , Echinostoma/ultraestrutura , Genes de Helmintos/genética , Humanos , Mesocricetus/parasitologia , Metacercárias/genética , Metacercárias/crescimento & desenvolvimento , Metacercárias/ultraestrutura , Microscopia Eletrônica de Varredura , Filogenia
10.
Exp Parasitol ; 224: 108098, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33713659

RESUMO

Molecular diagnostics are powerful tools for disease detection but are typically confined to the laboratory environment due to the cumbersome methods required to extract nucleic acids from biological samples. Accurate diagnosis is essential for early detection of parasitic worm infections and for monitoring control programs, particularly during new transmission outbreaks to limit infection spread. We optimized the recently developed DNA dipstick technology to purify Schistosoma japonicum DNA from different life stages in <60 s. We successfully detected DNA from adult worms, eggs and infected snails. The speed and simplicity of this method enables the point-of-care detection of S. japonicum.


Assuntos
DNA de Helmintos/isolamento & purificação , Schistosoma japonicum/isolamento & purificação , Esquistossomose Japônica/diagnóstico , Animais , Fígado/parasitologia , Camundongos , Técnicas de Diagnóstico Molecular , Técnicas de Amplificação de Ácido Nucleico , Testes Imediatos , Reação em Cadeia da Polimerase em Tempo Real , Schistosoma japonicum/genética , Esquistossomose Japônica/prevenção & controle , Caramujos/parasitologia
11.
Parasitol Int ; 83: 102318, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33689826

RESUMO

An unknown species of the genus Notocotylus (Digenea: Notocotylidae) was found as the larval stage from the lymnaeid snail, Radix auricularia, in a static water area of the Chubetsu River, Hokkaido, the northernmost island of Japan. A DNA barcoding identification system was applied to detect the adult stage. Through the inspection of anatid game birds in Hokkaido, Anas crecca, Anas platyrhynchos, Anas zonorhyncha, and Mareca penelope were demonstrated to serve as the definitive hosts. The detailed morphological features of the species were characterized using adults raised experimentally in immunosuppressed mice and naturally developed larvae in R. auricularia. Although the species is morphologically similar to Notocotylus attenuatus and Notocotylus magniovatus in both adult and larval stages, its taxonomic independence was confirmed by a comprehensive study based on molecular phylogeny, morphology, and ecology. Here we propose Notocotylus ikutai n. sp. for this species. The migratory behavior of the anatid hosts and the North-Eurasian distribution of R. auricularia suggest that the new species is widely distributed in the northern Far East.


Assuntos
Doenças das Aves/epidemiologia , Patos , Caramujos/parasitologia , Trematódeos/classificação , Infecções por Trematódeos/veterinária , Animais , Animais Selvagens , Doenças das Aves/parasitologia , Japão/epidemiologia , Microscopia Eletrônica de Varredura , Filogenia , Prevalência , RNA de Helmintos/análise , RNA Ribossômico 28S/análise , Trematódeos/citologia , Trematódeos/genética , Trematódeos/ultraestrutura , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/parasitologia
12.
Parasitol Int ; 83: 102329, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33753234

RESUMO

The cryptic diversity of trematodes was evaluated in the Nagayama-Shinkawa River, an artificial canal of the Ishikari River System of Hokkaido, Japan. Numerous migratory waterfowls use the canal as a stopover point in every spring season. The lymnaeid snail, Radix auricularia, and the semisulcospirid snail, Semisulcospira libertina, colonize the static and flowing water areas, respectively. The trematode fauna of the two snails was assessed by molecular phylogenetic and population genetic analyses. Each of distinctive clades in mitochondrial DNA trees was arbitrarily set as a species. In total, 14 species of the families Diplostomidae, Echinostomatidae, Notocotylidae, Plagiorchiidae, and Strigeidae occurred in R. auricularia, wherease S. libertina harbored 10 species of the families Echinochasmidae, Heterophyidae, Notocotylidae, and Lecithodendridae and Cercaria creta, an unclassified species whose adult stage is still unknown. The species diversity of the larval trematodes could be recognized as a "hot spot", suggesting that the seasonal visit of waterfowls is very important to spread trematodes and to keep their diversity. A high intraspecific genetic diversity was observed in the echinostomatid, notocotylid, echinochasmid, and heterophyid species, whose definitive hosts include birds. It seems likely that each of the parasite populations is always disturbed by repeated visits of waterfowls.


Assuntos
Interações Hospedeiro-Parasita , Caramujos/parasitologia , Trematódeos/fisiologia , Migração Animal , Animais , Anseriformes/fisiologia , Japão , Filogenia , RNA de Helmintos/análise , RNA Ribossômico 28S/análise , Rios/parasitologia , Estações do Ano
13.
PLoS Negl Trop Dis ; 15(2): e0009120, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33544705

RESUMO

Paragonimiasis is caused by zoonotic trematodes of Paragonimus spp., found in Asia, the Americas and Africa, particularly in tropical regions. These parasites have a complex, multi-host life cycle, with mammalian definitive hosts and larval stages cycling through two intermediate hosts (snails and freshwater decapod crustaceans). In Africa, paragonimiasis is particularly neglected, and remains the only human parasitic disease without a fully characterised life cycle. However paragonimiasis has potentially significant impacts on public health in Africa, and prevalence has likely been underestimated through under-reporting and misdiagnosis as tuberculosis due to a similar clinical presentation. We identified the need to synthesise current knowledge and map endemic foci for African Paragonimus spp. together with Poikilorchis congolensis, a rare, taxonomically distant trematode with a similar distribution and morphology. We present the first systematic review of the literature relating to African paragonimiasis, combined with mapping of all reported occurrences of Paragonimus spp. throughout Africa, from the 1910s to the present. In human surveys, numerous reports of significant recent transmission in Southeast Nigeria were uncovered, with high prevalence and intensity of infection. Overall prevalence was significantly higher for P. uterobilateralis compared to P. africanus across studies. The potential endemicity of P. africanus in Côte d'Ivoire is also reported. In freshwater crab intermediate hosts, differences in prevalence and intensity of either P. uterobilateralis or P. africanus were evident across genera and species, suggesting differences in susceptibility. Mapping showed temporal stability of endemic foci, with the majority of known occurrences of Paragonimus found in the rainforest zone of West and Central Africa, but with several outliers elsewhere on the continent. This suggests substantial under sampling and localised infection where potential host distributions overlap. Our review highlights the urgent need for increased sampling in active disease foci in Africa, particularly using molecular analysis to fully characterise Paragonimus species and their hosts.


Assuntos
Paragonimíase/epidemiologia , Paragonimíase/transmissão , Paragonimus , Animais , Bases de Dados Factuais , Humanos , Estágios do Ciclo de Vida , Pulmão , Prevalência , Saúde Pública , Caramujos/parasitologia
14.
PLoS One ; 16(2): e0247312, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33630891

RESUMO

BACKGROUND: Schistosoma constitutes a major public health problem and developmental challenges in the majority of developing and subtropical regions. The World Health Organization has set guidelines for the control and elimination of schistosomiasis. Ethiopia is providing school-based Mass Drug Administration (MDA) at the study areas of the Abbey and Didessa Valleys of western Ethiopian since 2015. Moreover, mass treatment was already done in the same villages 30 years ago. However, the current Schistosoma mansoni infection status among humans and snails in the study areas is not known. Hence, the present study aims to determine the current status. METHODS: A community-based cross-sectional study was conducted in the three communities; Chessega, Agallu Metti and Shimala in Schistosoma mansoni endemic areas of the Abbey and Didessa valleys in Western Ethiopia. Using the list of households obtained from the Kebele administration, a systematic sampling technique was used to select households in each village. RESULTS: Even though the area is under the Ethiopian national Mass Drug Administration campaign, the present study reports prevalence above 50%. Although the majority of the infections were moderate, we found that 13% had heavy infection, above 400 eggs per gram of stool, which is at the same level as before the treatment campaign 30 years ago. The infection was significantly higher among those below 12 years of age, among non-attending school-age children and daily laborers. CONCLUSION: Schistosoma mansoni infection is still a public health problem in the study areas, despite control efforts already 30 years ago and present mass treatment in the last years. We suggest making the mass treatment campaign just early after the rainy season, when the snails are washed away. This should be supplemented with provisions of clean water, sanitation, and hygiene (WASH) and reduction of water contact and possible snail control efforts' to prevent reinfection.


Assuntos
Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/epidemiologia , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Estudos Transversais , Meio Ambiente , Etiópia/epidemiologia , Fezes/parasitologia , Feminino , Humanos , Higiene , Masculino , Administração Massiva de Medicamentos , Prevalência , População Rural , Saneamento/métodos , Instituições Acadêmicas , Caramujos/parasitologia , Adulto Jovem
15.
PLoS Negl Trop Dis ; 15(2): e0008995, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33630833

RESUMO

BACKGROUND: Schistosomiasis is a parasitic disease caused by trematode worms of the genus Schistosoma and belongs to the neglected tropical diseases. The disease has been reported in 78 countries, with around 290.8 million people in need of treatment in 2018. Schistosomiasis is predominantly considered a rural disease with a subsequent focus of research and control activities in rural settings. Over the past decades, occurrence and even expansion of schistosomiasis foci in peri-urban and urban settings have increasingly been observed. Rural-urban migration in low- and middle-income countries and subsequent rapid and unplanned urbanization are thought to explain these observations. Fifty-five percent (55%) of the world population is already estimated to live in urban areas, with a projected increase to 68% by 2050. In light of rapid urbanization and the efforts to control morbidity and ultimately achieve elimination of schistosomiasis, it is important to deepen our understanding of the occurrence, prevalence, and transmission of schistosomiasis in urban and peri-urban settings. A systematic literature review looking at urban and peri-urban schistosomiasis was therefore carried out as a first step to address the research and mapping gap. METHODOLOGY: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic computer-aided literature review was carried out using PubMed, ScienceDirect, and the World Health Organization Database in November 2019, which was updated in March 2020. Only papers for which at least the abstract was available in English were used. Relevant publications were screened, duplicates were removed, guidelines for eligibility were applied, and eligible studies were reviewed. Studies looking at human Schistosoma infections, prevalence, and intensity of infection in urban and peri-urban settings were included as well as those focusing on the intermediate host snails. PRINCIPAL FINDINGS: A total of 248 publications met the inclusion criteria. The selected studies confirm that schistosomiasis is prevalent in peri-urban and urban areas in the countries assessed. Earlier studies report higher prevalence levels in urban settings compared to data extracted from more recent publications, yet the challenge of migration, rapid uncontrolled urbanization, and resulting poor living conditions highlight the potential for continuous or even newly established transmission to take place. CONCLUSIONS: The review indicates that schistosomiasis has long existed in urban and peri-urban areas and remains a public health problem. There is, however, a challenge of comparability of settings due to the lack of a clear definition of what constitutes urban and peri-urban. There is a pressing need for improved monitoring of schistosomiasis in urban communities and consideration of treatment strategies.


Assuntos
Schistosoma/isolamento & purificação , Esquistossomose/epidemiologia , Animais , Humanos , Schistosoma/classificação , Esquistossomose/transmissão , Caramujos/parasitologia , População Suburbana , População Urbana
16.
Vet Parasitol ; 291: 109373, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33578197

RESUMO

Livestock production around the world is impacted by liver fluke (Fasciola spp.) infection resulting in serious economic losses to the beef, dairy and sheep industries with significant losses of about $90 million per annum in Australia. Triclabendazole (TCBZ) is the most effective anthelmintic treatment available to control liver fluke infections; however, the widespread emergence of TCBZ resistance in livestock threatens liver fluke control. Alternative control measures to lower exposure of livestock to liver fluke infection would help to preserve the usefulness of current anthelmintic treatments. Environmental DNA (eDNA) based identification of liver fluke and the intermediate snail host in the water bodies is a robust method to assess the risk of liver fluke infection on farms. In this study, we used a multiplex quantitative PCR assay of water samples to detect and quantify eDNA of Fasciola hepatica (F. hepatica) and Austropeplea tomentosa (A. tomentosa), a crucial intermediate snail host for liver fluke transmission in South-east Australia. Water samples were collected from an irrigation channel for a period of 7 months in 2016 (February, March, May, September, October, November and December) at a dairy farm located at Maffra, Victoria, South-east Australia. Using an effective eDNA extraction method, the multiplex qPCR assay allows for the independent but simultaneous detection of eDNA released from liver fluke life stages and snails using specific primers and a probe targeting the ITS-2 region of the liver fluke and snail, respectively, with minimal inhibition from contaminants in field collected water samples. The sensitivity of this assay to detect eDNA of liver fluke and snails was observed to be 14 fg and 50 fg, respectively, in the presence of field collected water samples. Differential levels of liver fluke and snail specific eDNA in water were observed at the time points analysed in this study. The successful detection of eDNA specific to liver fluke and snails from the field collected water samples provides a precedent for the use of this method as a monitoring tool to determine the prevalence of liver fluke and liver fluke-transmitting snails in irrigation regions. Further, this method has the enormous potential to allow an assessment of the liver fluke transmission zones on farms and to inform the application of effective control strategies.


Assuntos
Doenças dos Bovinos/parasitologia , Doenças dos Bovinos/transmissão , DNA Ambiental/análise , Fasciola hepatica/genética , Fasciolíase/veterinária , Caramujos/parasitologia , Água/parasitologia , Animais , Bovinos , Indústria de Laticínios , DNA Ambiental/genética , Fasciolíase/transmissão
17.
Parasitology ; 148(7): 798-808, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33593464

RESUMO

Amphistome species belonging to the genus Catadiscus are poorly studied intestinal trematodes found primarily in Neotropical anurans. Herein, developmental stages of an amphistome species found during herpetological and malacological surveys in a temporary marsh pond from Brazil were subjected to morphological (light and scanning electron microscopy) and molecular analyses. Adult parasites recovered from anurans were identified as Catadiscus marinholutzi. Amphistome cercariae found in the planorbid snails Drepanotrema depressissimum and Drepanotrema lucidum from the same waterbody were used for experimental and molecular studies. Immature parasites, morphologically compatible with members of Catadiscus, were experimentally obtained in laboratory-reared tadpoles. Sequencing of a partial region of 28S rDNA gene of both adult and cercariae revealed 100% similarity between these developmental stages, confirming their conspecificity. Phylogenetic analyses were attempted for the first time to reveal the position of a species of Catadiscus in the superfamily Paramphistomoidea. Catadiscus marinholutzi falls in a virtual polytomy together with other paramphistomoids, which leaves its phylogenetic relationships within the group unclear. Moreover, the high genetic divergence to Diplodiscus spp. (10.06­10.84%) cast doubts on the placement of Catadiscus within Diplodiscidae. Hence the species composition of the Diplodiscidae should be re-evaluated in further studies using a broader spectrum of related taxa.


Assuntos
Anuros/parasitologia , Caramujos/parasitologia , Trematódeos/anatomia & histologia , Trematódeos/crescimento & desenvolvimento , Animais , Brasil , DNA de Helmintos/análise , DNA Ribossômico/análise , Filogenia , Trematódeos/classificação , Trematódeos/genética
18.
Parasit Vectors ; 14(1): 116, 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33618761

RESUMO

BACKGROUND: Flooding is considered to be one of the most important factors contributing to the rebound of Oncomelania hupensis, a small tropical freshwater snail and the only intermediate host of Schistosoma japonicum, in endemic foci. The aim of this study was to assess the risk of intestinal schistosomiasis transmission impacted by flooding in the region around Poyang Lake using multi-source remote sensing images. METHODS: Normalized Difference Vegetation Index (NDVI) data collected by the Landsat 8 satellite were used as an ecological and geographical suitability indicator of O. hupensis habitats in the Poyang Lake region. The expansion of the water body due to flooding was estimated using dual-polarized threshold calculations based on dual-polarized synthetic aperture radar (SAR). The image data were captured from the Sentinel-1B satellite in May 2020 before the flood and in July 2020 during the flood. A spatial database of the distribution of snail habitats was created using the 2016 snail survey in Jiangxi Province. The potential spread of O. hupensis snails after the flood was predicted by an overlay analysis of the NDVI maps in the flood-affected areas around Poyang Lake. The risk of schistosomiasis transmission was classified based on O. hupensis snail density data and the related NDVI. RESULTS: The surface area of Poyang Lake was approximately 2207 km2 in May 2020 before the flood and 4403 km2 in July 2020 during the period of peak flooding; this was estimated to be a 99.5% expansion of the water body due to flooding. After the flood, potential snail habitats were predicted to be concentrated in areas neighboring existing habitats in the marshlands of Poyang Lake. The areas with high risk of schistosomiasis transmission were predicted to be mainly distributed in Yongxiu, Xinjian, Yugan and Poyang (District) along the shores of Poyang Lake. By comparing the predictive results and actual snail distribution, we estimated the predictive accuracy of the model to be 87%, which meant the 87% of actual snail distribution was correctly identified as snail habitats in the model predictions. CONCLUSIONS: Data on water body expansion due to flooding and environmental factors pertaining to snail breeding may be rapidly extracted from Landsat 8 and Sentinel-1B remote sensing images. Applying multi-source remote sensing data for the timely and effective assessment of potential schistosomiasis transmission risk caused by snail spread during flooding is feasible and will be of great significance for more precision control of schistosomiasis.


Assuntos
Lagos/química , Tecnologia de Sensoriamento Remoto/métodos , Esquistossomose/transmissão , Caramujos/crescimento & desenvolvimento , Distribuição Animal , Animais , China/epidemiologia , Ecossistema , Inundações , Humanos , Lagos/parasitologia , Dinâmica Populacional , Imagens de Satélites , Schistosoma japonicum/fisiologia , Esquistossomose/epidemiologia , Esquistossomose/parasitologia , Caramujos/parasitologia , Caramujos/fisiologia
19.
Parasit Vectors ; 14(1): 7, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407789

RESUMO

BACKGROUND: Constant emerging sites infested with Oncomelania hupensis (O. hupensis) impede the goal realization of eliminating schistosomiasis. The study assessed the spatial and temporal distributions of new Oncomelania snail habitats in Hunan Province from 1949 to 2016. METHODS: We used the data from annual snail surveys throughout Hunan Province for the period from 1949 to 2016. Global Moran's I, Anselin local Moran's I statistics (LISA) and a retrospective space-time permutation model were applied to determine the spatial and temporal distributions of emerging snail-infested sites. RESULTS: There were newly discovered snail-infested sites almost every year in 1949-2016, except for the years of 1993, 2009 and 2012. The number of emerging sites varied significantly in the five time periods (1949-1954, 1955-1976, 1977-1986, 1986-2003 and 2004-2016) (H = 25.35, p < 0.05). The emerging sites lasted 37.52 years in marshlands, 30.04 years in hills and 24.63 at inner embankments on average, with the values of Global Moran's I being 0.52, 0.49 and 0.44, respectively. High-value spatial clusters (HH) were mainly concentrated along the Lishui River and in Xiangyin County. There were four marshland clusters, two hill clusters and three inner embankment clusters after 1976. CONCLUSIONS: Lower reaches of the Lishui River and the Dongting Lake estuary were the high-risk regions for new Oncomelania snail habitats with long durations. Snail surveillance should be strengthened at stubborn snail-infested sites at the inner embankments. Grazing prohibition in snail-infested grasslands should be a focus in marshlands. The management of bovines in Xiangyin County is of great importance.


Assuntos
Esquistossomose/transmissão , Caramujos , Distribuição Animal , Animais , Bovinos , China/epidemiologia , Reservatórios de Doenças/parasitologia , Vetores de Doenças , Ecossistema , Estuários , Humanos , Lagos , Estudos Retrospectivos , Rios , Schistosoma , Caramujos/parasitologia , Caramujos/fisiologia , Análise Espaço-Temporal , Zoonoses/parasitologia , Zoonoses/transmissão
20.
Parasitol Int ; 82: 102284, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33450355

RESUMO

Xiphidiocercariae were found in the invasive snail Melanoides tuberculata collected during a malacological survey in Ceará-Mirim, State of Rio Grande do Norte, Northeastern Brazil in November 2018 and submitted to morphological and molecular analyses. The morphology revealed similarities between the larvae here reported for the first time in M. tuberculata from Brazil and other xiphidiocercariae described in thiarid snails from Asia and Africa. Phylogenetic analyses based on 28S and ITS-2 sequences revealed that the larvae correspond to an unidentified species of the family Lecithodendriidae. Aspects related to the morphology and taxonomy of xiphidiocercariae found in M. tuberculata are briefly discussed. It is possible that the parasite here reported is a newly introduced species transmitted by M. tuberculata in the American continent.


Assuntos
Distribuição Animal , Interações Hospedeiro-Parasita , Espécies Introduzidas , Caramujos/parasitologia , Trematódeos/classificação , Animais , Brasil , Cercárias/classificação , Cercárias/crescimento & desenvolvimento , Filogenia , RNA de Helmintos/análise , RNA Ribossômico 28S/análise , Trematódeos/crescimento & desenvolvimento
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