Molecular tracing of Biomphalaria straminea in China / 中国血吸虫病防治杂志

Objective To investigate the origin of Biomphalaria straminea in China, so as to provide insights into assessment of schistosomiasis mansoni transmission risk and B. straminea control. Methods Guanlan River, Dasha River, Shenzhen Reservoir, upper and lower reaches of Kuiyong River, and Xinzhen River in Shenzhen, China, were selected as sampling sites. Ten Biomphalaria samples were collected from each site, and genomic DNA was extracted from Biomphalaria samples. DNA samples were obtained from 15 B. straminea sampled from 5 sampling sites in Minas Gerais State, Pará State, Federal District, Pernambuco State, and Sao Paulo State in Brazil, South America. Cytochrome c oxidase I (COI) and mitochondrial 16S ribosomal RNA (16S rRNA) genes were sampled using the above DNA templates, and the amplified products were sequenced. The COI and 16S rRNA gene sequences were downloaded from GenBank, and the sampling sites were acquired. All COI and 16S rRNA gene sequences were aligned and evolutionary trees of B. straminea were created based on COI and 16S rRNA gene sequences to identify the genetic similarity and evolutionary relationship between B. straminea samples from China and South America. Results A total of 60 COI gene sequences with a length of 529 bp and 3 haplotypes were obtained from B. straminea sampled from China. There were 165 COI gene sequences of B. straminea retrieved from GenBank, and following alignment with the above 60 gene sequences, a total of 33 haplotypes were obtained. Phylogenetic analysis showed that the three haplotypes of B. straminea from China were clustered into one clade, among which the haplotype China11 and three B. straminea samples from Brazil retrieved from GenBank belonged to the same haplotype. Geographical evolution analysis showed that the B. straminea samples from three sampling sites along eastern coasts of Brazil had the same haplotype with China11, and B. straminea samples from other two sampling sites were closely, genetically related to China11. A total of 60 16S rDNA gene sequences with approximately 322 bp in length were amplified from B. straminea in China, with 2 haplotypes identified. A total of 70 16S rDNA gene sequences of B. straminea were captured from GenBank. Phylogenetic analysis showed that Biomphalaria snails collected from China were clustered into a clade, and the haplotype China64 and the haplotype 229BS from Brazil shared the same haplotype. The 49 16S rDNA gene sequences of B. straminea from 25 sampling sites in southern Brazil, which were captured from GenBank, were included in the present analysis, and the B. straminea from 3 sampling sites shared the same haplotype with China64 in China. Geographical evolution analysis based on COI and 16S rRNA gene sequences showed that B. straminea sampled from eastern coastal areas of Brazil shared the same haplotypes in two gene fragment sequences with Biomphalaria snails collected from China. Conclusions The Biomphalaria snails in China are characterized as B. straminea, which have a low genetic diversity. The Biomphalaria snails in China have a high genetic similarity with B. straminea sampled from eastern coastal areas of Brazil, which may have originated from the eastern coastal areas of Brazil.

Modelagem GAMLSS espaçotemporal da incidência de esquistossomose na região central do Estado de Minas Gerais, Brasil / Modelado espaciotemporal GAMLSS para la incidencia de esquistosomiasis en la región central del estado de Minas Gerais, Brasil / Spatio-temporal GAMLSS modeling of the incidence of schistosomiasis in the central region of the State of Minas Gerais, Brazil

Resumo: No Brasil, milhões de pessoas vivem em áreas de risco para a esquistossomose, uma doença negligenciada, de caráter crônico e com elevada morbidade. O helminto Schistosoma mansoni está presente em todas as macrorregiões, incluindo o Estado de Minas Gerais, um dos mais endêmicos. Por essa razão, a identificação de potenciais focos é fundamental para subsidiar políticas públicas de cunho educativo e profilático no controle desse desfecho. Nesse contexto, o objetivo do trabalho consiste em modelar dados de esquistossomose em relação aos aspectos espaciais e temporais, além de avaliar a importância de algumas variáveis exógenas socioeconômicas e a presença das principais espécies de Biomphalaria. Como trabalhar com casos incidentes, uma variável discreta de contagem, exige uma modelagem apropriada, foi escolhida a modelagem GAMLSS por considerar conjuntamente uma distribuição mais adequada à variável resposta devido à inflação de zeros e à heterocedasticidade espacial. Verificaram-se valores elevados de incidência em diversos municípios de 2010 a 2012 e uma tendência de queda até 2020. Também foi identificado que a distribuição da incidência se comporta de maneira diferente no espaço e no tempo. Municípios com barragem apresentaram risco 2,25 vezes maior do que os que não a continham. A presença de B. glabrata foi relacionada ao risco de ocorrência da doença. Por outro lado, a presença de B. straminea refletiu em menor risco de ocorrência da esquistossomose. Conclui-se que o controle e o acompanhamento dos caramujos da B. glabrata podem ser fundamentais para a contenção e a eliminação da esquistossomose e o modelo GAMLSS foi eficaz para tratamento e modelagem de dados espaçotemporais.

Resumen: En Brasil, millones de personas viven en áreas de riesgo de esquistosomiasis, una enfermedad crónica desatendida y con alta morbilidad. El helminto Schistosoma mansoni está presente en todas las macrorregiones, incluido el Estado de Minas Gerais, uno de los más endémicos del país. Por ello, la identificación de potenciales brotes es fundamental para promover políticas públicas de carácter educativo y profiláctico en el control de este desenlace. En este contexto, el objetivo de este trabajo es modelar datos sobre esquistosomiasis con respecto a aspectos espaciotemporales, además de evaluar la importancia de algunas variables socioeconómicas exógenas y la presencia de las principales especies de Biomphalaria. Dado que en el trabajo con casos incidentes una variable de conteo discreta requiere un adecuado modelado, se eligió el modelo GAMLSS, ya que en conjunto considera una distribución más adecuada para la variable de respuesta debido a la inflación de ceros y la heterocedasticidad espacial. Se encontraron valores de alta incidencia en varios municipios en el periodo evaluado de 2010 a 2012 y una tendencia a descenso hasta 2020. También se verificó que existe una distribución de incidencia de manera diferente en el espacio y el tiempo. Los municipios con represas presentaban 2,25 veces más riesgo que los que no las tenían. La presencia de B. glabrata estuvo relacionada con el riesgo de la enfermedad. Por otro lado, la presencia de B. straminea ocasionaba un menor riesgo de padecer la enfermedad. Se concluye que el control y seguimiento de caracoles B. glabrata puede ser fundamental para el control y eliminación de la esquistosomiasis y que el modelo GAMLSS resultó ser efectivo para el tratamiento y modelado de datos espaciotemporales.

Abstract: In Brazil, millions of people live in areas with risk of schistosomiasis, a neglected chronic disease with high morbidity. The Schistosoma mansoni helminth is present in all macroregions of Brazil, including the State of Minas Gerais, one of the most endemic states. For this reason, the identification of potential foci is essential to support educational and prophylactic public policies to control this disease. This study aims to model schistosomiasis data based on spatial and temporal aspects and assess the importance of some exogenous socioeconomic variables and the presence of the main Biomphalaria species. Considering that, when working with incident cases, a discrete count variable requires an appropriate modeling, the GAMLSS modeling was chosen since it jointly considers a more appropriate distribution for the response variable due to zero inflation and spatial heteroscedasticity. Several municipalities presented high incidence values from 2010 to 2012, and a downward trend was observed until 2020. We also noticed that the distribution of incidence behaves differently in space and time. Municipalities with dams presented risk 2.25 times higher than municipalities without dams. The presence of B. glabrata was associated with the risk of schistosomiasis. On the other hand, the presence of B. straminea represented a lower risk of the disease. Thus, the control and monitoring of B. glabrata snails is essential to control and eliminate schistosomiasis; and the GAMLSS model was effective in the treatment and modeling of spatio-temporal data.

Study on the relationship between habitat factors and the distribution / 公共卫生与预防医学

Objective To explore the relationship between the distribution characteristics and the habitat factors of the invasive B. straminea in South China. Methods From October 2016 to August 2017, the breeding condition and habitat factors of B. straminea were investigated in the rivers of Shenzhen and its adjacent areas in the dry season, normal season and wet reason. The generalized additive model (GAM) was used to study the main habitat factors affecting the distribution density of B. straminea. Results The distribution characteristics of B. straminea showed obvious aggregation and unevenness in space. In terms of time, the density of snails was the highest in the dry season, followed by the normal water season and the least in the wet season. The GAM model analysis showed that the main habitat factors affecting the distribution density of B. straminea were water depth, water temperature, flow velocity, dissolved oxygen, and total phosphorus. When the flow velocity and water temperature were 0.25 m / s and 26 °C, respectively, the largest distribution density of snails might appear. The distribution density of B. straminea was positively correlated with dissolved oxygen and total phosphorus. Conclusion B. straminea is suitable to live in the water environment with poor water quality. In the future, the monitoring should be strengthened to provide reference for the prevention and control of the spread of the snails.

Geographic Information System-based association between the sewage network, geographical location of intermediate hosts, and autochthonous cases for the estimation of risk areas of schistosomiasis infection in Ourinhos, São Paulo, Brazil

Abstract INTRODUCTION: Ourinhos is a municipality located between the Pardo and Paranapanema rivers, and it has been characterized by the endemic transmission of schistosomiasis since 1952. We used geospatial analysis to identify areas prone to human schistosomiasis infections in Ourinhos. We studied the association between the sewage network, co-occurrence of Biomphalaria snails (identified as intermediate hosts [IHs] of Schistosoma mansoni), and autochthonous cases. METHODS: Gi spatial statistics, Ripley's K12-function, and kernel density estimation were used to evaluate the association between schistosomiasis data reported during 2007-2016 and the occurrence of IHs during 2015-2017. These data were superimposed on the municipality sewage network data. RESULTS: We used 20 points with reported IH; they were colonized predominantly by Biomphalaria glabrata, followed by B. tenagophila and B. straminea. Based on Gi statistics, a significant cluster of autochthonous cases was superimposed on the Christoni and Água da Veada water bodies, with distances of approximately 300 m and 2200 m from the points where B. glabrata and B. straminea were present, respectively. CONCLUSIONS: The residence geographical location of autochthonous cases allied with the spatial analysis of IHs and the coverage of the sewage network provide important information for the detection of human-infection areas. Our results demonstrated that the tools used for direct surveillance, control, and elimination of schistosomiasis are appropriate.

Efficiency of Three Extracts of Carica papaya as Molluscicidal and Anti-schistosomal Agents against Biomphalaria alexandrina and Schistosoma mansoni by Flow Cytometry

Schistosomiasis a prevalent parasitic disease in tropical and sub-tropical areas, which comes in the second place in terms of socioeconomic and public health burden. Around 600 million people in 74 countries are infected yearly, predominantly in the developing world. The aim of this work was to assess the efficiency of three extracts from Carica papaya (methanol, ethanol and butanol extracts) for their molluscicidal and anti-schistosomal activities. The LC50of methanol, ethanol and butanol extracts of Carica papaya against B. alexandrinea were 180, 499.3 and 509.1 mg/L while the respective LC90values were 220.3, 700.6, 769.6 mg/L respectively. The effect of these extracts on Biomphalaria alexandrina snails and larval stages of Schistosma mansoni, for miracidia the LC50of methanol, ethanol and butanol extracts ofCaricapapaya against miracidia were 3.4, 15.4and 8.1 mg/L, respectively, while the respective LC90values were 8.4, 38.2, 11.2 mg/L, and for cercariae the LC50of methanol, ethanol and butanol extracts ofCaricapapaya were 2, 20and 4mg/L, while the respective LC90values were 13.5, 80.5, 18.5mg/L respectively was evaluated, in addition to flowcytometric analysis of CD4, CD25, FOXP3 and TGF-βlevels during S. mansoniinfection in mice. The in-vivo results showed that the three extracts have variable potential against snails and miracidia and cercariae ofS. mansoni. The mortality rate in B. alexandrinasnails for methanol, ethanol and butanol extracts ofCarcia papaywere 86%, 45% and 64%, respectively. While it was 83%, 35% and 66%, respectively in miracidia and 92%, 40% and 70%, respectively in cercariae. The results indicated that methanol extract from Carica papaya recorded higher activity against snails, miracidia and cercariae. The levels of CD4, CD25, FOXP3 regulatory T (Treg) cells were decreased significantly (p<0.001) in infected mice compared to healthy controls. However, there was a significant (p<0.001) increase in levels of TGF-β. A significant increase in the levels of CD4, CD25, and FOXP3 Treg in Carica papaya treated group compared to infected control group, with a significant (p<0.001) decrease in TGF-βlevel than infected group. In conclusion, methanol extract was more effective at concentration of LC50 180 and LC90 220.3than ethanol and butanol extracts ofCaricapapaya therefore controlling B. alexandrinasnails by methanol extract is a promising way as it is an eco-friendly strategy in rural areas of developing countries, where schistosomiasis is endemic. Moreover, the increased immune defense mechanism in treated group with the same extracts is a promising target for new immune modulatory strategies against schistosomiasis

Estudo da composição química, toxicidade e atividade moluscicida do óleo essencial Citrus sinensis (L.) Osbeck / Study of the chemical composition, toxicity and molluscicidal activity of the essential oil Citrus sinensis (L.) Osbeck

RESUMO Determinamos a composição química e testamos a toxicidade e a atividade moluscicida do óleo essencial extraído das cascas do Citrus sinensis (L.) Osbeck. Para isso, o óleo essencial foi extraído quantitativamente por hidrodestilação. Em seguida, as quantificações de seus componentes foram realizadas por cromatografía gasosa acoplada à espectrometria de massas (CG-MS) e a toxicidade e atividade moluscicida foram testadas, respectivamente, contra Artemia salina e caramujos Biomphalaria glabrata. Os resultados mostraram que o óleo contém 81,50% de D-limoneno (constituinte principal) e 0,06% de citronelal (componente menor) e este possui atividade moluscicida com concentração letal (CL50) de 100,08 mg.L-1 e atoxicidade, com CL50 de 321,84 mg.L-1 a um nível de confiança de 95%. Portanto, o óleo é ativo contra o caramujo Biomphalariaglabrata e atóxico para outros seres vivos.

SUMMARY In this present study, we determined the chemical composition and we tested the toxicity and the molluscicidal activity of the essential oil extracted from the barks of Citrus sinensis (L.) Osbeck. For this, the essential oil was extracted quantitatively by hydrodistillation. Then, quantifications of its components were performed by gas chromatography coupled to mass spectrometry (CG-MS) and the toxicity and molluscicidal activity were tested, respectively, against Artemia salina and snails Biomphalaria glabrata. The results showed that the oil contains 81.50% of D-limonene (main constituent) and 0.06% of citronellal (minor component) and it has lethal activity (LC50) of 100.08 mg.L-1 and a toxicity, with LC50 of321.84 mg.L -1 at a 95% confidence level. Therefore, the oil is active against the snail Biomphalaria glabrata and non-toxic to other living bein.

Preliminary study on the diffusion dynamics characteristics of Biomphalaria straminea in Southern China / 公共卫生与预防医学

Objective To study the dynamic diffusion characteristics of Biomphalaria straminea in Shenzhen, Dongguan and Huizhou of Southern China. Methods B. straminea was monitored at 25 investigation points along 10 river channels in Shenzhen, Dongguan and Huizhou by salvaging method. The diffusion characteristics of snails along with water in the Guihua New Village section of the Guanlan River and the Dawei Village section of the Longgang River were analyzed by GPS location drift test. In addition, the influence of flooding on the diffusion of B. straminea in the Kuichong River both before and after Typhoon "Shanzhu" was analyzed by monitoring the hydrology and distribution of snails. Results In March and October from 2016 to 2018, a total of 1 176 kg of floating objects were salvaged in rivers in Shenzhen, Dongguan and Huizhou. Scattered B. straminea were found on water hyacinths. Drift test of floats with GPS showed that the average drift speed of GPS floating objects was close to the river surface velocity. Affected by river current and wind direction, the GPS floats quickly drifted to the river bank and stopped in the stagnant area due to the blockade of water plants, stone and the bending of the shoreline. The drift distance of each time was between 136 - 715m. The test results of salvaged floating objects found that the loss rates of B. straminea were 46.70% - 60.00% and 22.10% - 30.80%, in the Guihua New Village section of the Guanlan River and the Dawei Village section of the Longgang River, respectively, which were significantly affected by the floating weight, river velocity and drifting distance. The analysis of the hydrology and distribution of B. straminea in the Kuichong River both before and after Typhoon "Shanzhu" showed that the density of B. straminea in the river was significantly reduced by the flood. Conclusion B. straminea is mainly transported as suspended matter in water body, and flooding was an important factor in its long-distance diffusion.

Ocotea pulchellaas an alternative against schistosomiasis: chemical analysis, development of nanoemulsion and biological control activity / Ocotea pulchellacomo una alternativa ante esquistosomiasis: análisis químico, desarrollo de una nanoemulsión y actividad en control biológico

The aim of this work was to evaluate the potential of the essential oil (EO) from Ocotea pulchella leaves as an alternative in the control of schistosomiasis. It was tested O. pulchella EO nanoformulation to assess its activity against adult Biomphalaria glabrata, their spawning and Schistossoma mansoni cercariae. Additionally, the EO chemical composition was investigated by gas-chromatography. Nanoemulsion were elaborated by the low energy method. The adult mollusks, their spawning and cercariae were placed in contact with nanoemulsion to calculate lethal concentrations. Myristicin, bicyclogermacrene and α-Pinene were the main substances in the EO. Nanoemulsion caused mortality of adult B. glabrata, its egg embryos and S. mansoni. These results suggest the use of this nanoemulsion as an alternative in the control of the schistosomiasis cycle.

El objetivo de este trabajo fue evaluar el potencial de los aceites esenciales (AE) de las hojas de Ocotea pulchellacomo una alternativa en el control de esquistosomiasis. Se probó una nanoformulación de AE de O. pulchellapara evaluar su actividad ante adultos de Biomphalaria glabrata, sus huevos y cercarías de Schistossoma mansoni. La nanoemulsión fue elaborada por el método de baja energía. Los moluscos adultos, sus huevos y cercarías se colocaron en contacto con la nanoemulsión para calcular concentraciones letales. Los compuestos mayoritarios en el AE fueron miristicina, biciclogermacreno y α-pineno. La nanoemulsión causó mortalidad en adultos de B. glabrata, sus huevos y a S. mansoni. Los resultados sugieren el uso de esta nanoemulsión como una alternativa en el control del ciclo de esquistosomiasis.

Interaction of Biomphalaria cells in primary cultures with Schistosoma mansoni sporocysts

Abstract INTRODUCTION: Biomphalaria snails may display varying levels of susceptibility to Schistosoma mansoni infection. We have been developing an in vitro model to study the interaction between the snail and the parasite, using tissue-derived cell cultures from Biomphalaria. METHODS: The digestive gland- and kidney-derived cells from primary cultures of resistant (B. tenagophila Taim) and susceptible (B. tenagophila HM and B. glabrata BH) strains of Biomphalaria were exposed to S. mansoni sporocysts. RESULTS: S. mansoni sporocysts were surrounded and encapsulated exclusively by cells derived from the digestive gland (DG) of B. tenagophila Taim. The process was followed by a marked decrease in the number of free sporocysts in the culture medium. The morphological characteristics of DG-derived cells in culture have been described. CONCLUSIONS: Cells derived from DG (but not SK) primary cultures of B. tenagophila Taim may participate in S. mansoni sporocyst control.

Avaliação da toxicidade e atividade moluscicida do óleo essencial Cinnamomum zeylanicum Blume contra o caramujo Biomphalaria glabrata (Say, 1818) / Evaluation of toxicity and molluscicidal activity of the essential oil Cinnamomum zeylanicum Blume against the snail Biomphalariaglabrata (Say, 1818)

RESUMO Este trabalho determina a toxicidade e o efeito moluscicida do óleo extraído das folhas de Cinnamomum zeylanicum Blume contra o caramujo Biomphalaria glabrata (Say, 1818). Para isso, o óleo essencial foi extraído quantitativamente por hidro-destilação. Em seguida, quantificações de seus componentes foram realizadas por cromatografia gasosa acoplada a espectrometria de massas (CG-MS) e a toxicidade e atividade moluscicida do óleo foram testadas, respectivamente, contra Artemia salina e caramujos Biomphalaria glabrata (Say, 1818). A concentração letal (CL50) foi calculada a partir dos métodos Reed-Muench & Pizzi, respectivamente, para toxicidade e teste moluscicida. Os resultados das análises cromatográficas mostraram que o óleo possui 83% de eugenol (constituinte majoritário) e 2,5% de humuleno (componente minoritário). Na avaliação de toxicidade, o óleo foi considerado moderadamente tóxico com uma CL50 de 162,1 mg.L-1 ± 2,80, com intervalo de confiança de 95%, enquanto a atividade moluscicida apresentou concentração letal de 50% (CL50) de 18,62 mg.L-1 ± 2,18, com intervalo de confiança de 95%. Portanto, o óleo é ativo contra o caramujo Biom-phalaria glabrata.

SUMMARY This work determines the toxicity and the molluscicidal effect of the oil extracted from the leaves of Cinnamomum zeylanicum Blume against the snail Biomphalaria glabrata (Say, 1818). For this, the essential oil was extracted quantitatively by hydrodistillation. Then, quantifications of its components were performed by gas chro-matography coupled to mass spectrometry (CG-MS) and the toxicity and mollus-cicidal activity of the oil were tested, respectively, against Artemia salina and snails Biomphalaria glabrata (Say, 1818). The lethal concentration (LC50) was calculated from the Reed-Muench & Pizzi methods, respectively, for toxicity and molluscicide testing. The results of the chromatographic analysis showed that the oil has 83% eugenol (majority constituent) and 2.5% humulene (minority component). In the toxicity evaluation, the oil was considered to be moderately toxic with a LC50 of 162.1 mg.L-1 ± 2.80, with a 95% confidence interval, while the molluscicidal activity presented a lethal concentration of 50% (LC50) of 18.62 mg. L-1 ± 2.18, with a 95% confidence interval. Therefore, the oil is active against the snail Biomphalaria glabrata.

Toxicity and molluscicidal activity of the essential oil Pimenta dioica against the snail Biomphalaria glabrata / Toxicidad y actividad molusccidal del aceite esencial Pimenta dioica contra el caracol Biomphalaria glabrata

This work evaluated the toxicity and molluscicidal effect of the oil extracted from Pimenta dioica leaves against the snail Biomphalaria glabrata (Say, 1818). For this, the essential oil was extracted quantitatively by hydrodistillation. Then quantifications of its components were performed by gas chromatography coupled to mass spectrometry (CG-MS) and the toxicity and molluscicidal activity were tested, respectively, against Artemia salina and snails Biomphalaria glabrata (Say, 1818). The lethal concentration (LC50) was calculated from the Reed-Muench & Pizzi methods, respectively, for toxicity and molluscicide testing. The results of the chromatographic analysis showed that the oil contains 85.67% eugenol (major constituent) and 0.88% linalool (minor component). In the toxicity evaluation, the oil was considered highly toxic with a LC50 of 14.13 mg∙L-1, in a 95% confidence interval, while the molluscicidal activity presented a lethal concentration (LC50) of 18.62. mg∙L-1 at a 95% confidence interval. Therefore, the oil is active against the snail Biomphalaria glabrata.

Este trabajo evaluó la toxicidad y el efecto molusquicida del aceite extraído de las hojas de Pimenta dioica contra el caracol Biomphalaria glabrata (Say, 1818). Para esto, el aceite esencial se extrajo cuantitativamente por hidrodestilación. Luego se realizaron cuantificaciones de sus componentes mediante cromatografía de gases acoplada a espectrometría de masas (CG-MS) y se analizaron la toxicidad y la actividad molusquicida, respectivamente, contra Artemia salina y los caracoles Biomphalaria glabrata (Say, 1818). La concentración letal (CL50) se calculó a partir de los métodos de Reed-Muench y Pizzi, respectivamente, para pruebas de toxicidad y molusquicidas. Los resultados del análisis cromatográfico mostraron que el aceite contiene un 85,67% de eugenol (constituyente principal) y un 0,88% de linalool (componente secundario). En la evaluación de toxicidad, el aceite se consideró altamente tóxico con una CL50 de 14.13 mg∙L-1, en un intervalo de confianza del 95%, mientras que la actividad molusquicida presentó una concentración letal (CL50) de 18.62. mg∙L-1 en un intervalo de confianza del 95%. Por lo tanto, el aceite es activo contra el caracol Biomphalaria glabrata.

Study on biological characteristics: reproduction and viability of Biomphalaria glabrata as an intermediate host of Schistosoma mansoni / 中国血吸虫病防治杂志

Objective To compare the difference of fertility of Biomphalaria glabrata snails between self-fertilization and cross-fertilization and to observe the circadian rhythm of laying eggs, the effect of light on laying eggs and the tolerance of the snail to water and food deficiency, so as to provide the evidence for control and elimination of B. glabrata snails in the field. Methods Under laboratory conditions, a single B. glabrata egg for self-fertilization was separated and hatched individually, and young snails were raised in different plastic boxes individually. The eggs for cross-fertilization were hatched and the young snails were fed in the same plastic box. The ability of spawn, the development of the eggs, and the number of snails growing from young to adult snails were compared between the self-fertilization and cross-fertilization. The snails were in the water under four environments, all day illumination, all day without illumination, daytime lighting and night without illumination, and daytime without illumination but night lighting. The eggs were collected and counted daily. The circadian rhythm of spawn and the effect of illumination on spawn were observed. The adult snails were divided into 6 groups and exposed to the environments with relative humidity of 0, 65%, 87% and 100%, respectively. The survival rates of the adult snails exposed to the different environments after different time were observed. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were observed. Results In the 25 °C water, the average laying egg number for 15 days per snail was (8.77 ± 16.92) eggs/snail in the self-fertilization snail. The average laying egg number for 15 days per snail was (149.71 ± 142.28) eggs/snail in the cross-fertilization snails. There was a significant difference between the self-fertilization snail and cross-fertilization snail (t = 0.999 999, P < 0.01). The hatching rate and reproductive maturation rate of the self-fertilization snails and cross-fertilization snails were 50.1% and 78.9%, and 19.3% and 3.8%, respectively, There was a significant difference (the hatching rate: χ2 = 18.18, P < 0.01, the reproductive maturation rate: χ2 = 11.83, P < 0.01) . In the natural environment of daytime with illumination and nighttime with darkness, the amount of laying 20 eggs of B. glabrata snail was (944.07 ± 392.53) eggs/day during a whole day, among them the amount of laying eggs during daytime account for 10.1% and the amount of laying eggs during nighttime account for 89.9%, and the laying egg was given priority to with the night. The above results suggested that the dark environment was conducive to B. glabrata snails to lay eggs. The above results suggested that light can promote the increase of spawning of B. glabrata. When B. glabrata was exposed to the environments with the relative humidity of 0, 65%, 87% and 100% at 25 °C, respectively, and the longest survival times of snails were 7, 70, 150 d and 100 d, respectively. In the 25 °C water, the snails could survive for 50 days without food. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were 100%, 100%, 100%, 100%, 70%, 30%, 0, 0, 0 and 0, respectively. Conclusions B. glabrata can achieve the reproductive process by cross-fertilization or self-fertilization. There is a significant difference in reproductive ability between the cross-fertilization snail and self-fertilization snail, cross-fertilization is stronger than self-fertilization, but the rate of reproduction in the self-fertilization is higher than that in the cross-fertilization. It is indicated that B. glabrata that survive after the dry season plays an important role in the maintenance of local snail populations and transmission of schistosomiasis mansoni.

Progress of research on biologically invasive medical molluscs in China / 中国血吸虫病防治杂志

Invasion of alien species has increasingly become a major environmental problem that damages human health, economic development and ecological security in China, which has been paid much attention. Until now, there have been 753 invasive species reported in China, and invasive medical molluscs include Pomacea canaliculata, Achatina fulica, and Biomphalaria straminea. This review summarizes the status of biologically invasive species in China, describes the species and distribution of invasive medical molluscs, analyzes the damages of the invasive medical molluscs-transmitted diseases, and proposes the preventive and control measures.

Surveillance and control strategy of imported schistosomiasis mansoni: an expert consensus / 中国血吸虫病防治杂志

In 1980s, Biomphalaria straminea, an intermediate host of Schistosoma mansoni, was found in Shenzhen City, Guangdong Province, China, and currently, this snail has colonized in Shenzhen City and spread to peripheral cities involving of Dongguan and Huizhou. Since imported cases infected with S. mamoni have been reported from time to time in China, Mainland China is facing the potential risk of transmission of schistosomiasis mansoni. With the deepening of the opening-up policy, notably the implementation of the Belt and Road Initiative, there is an increase in the risk of transmission of schistosomiasis mansoni in Mainland China. Increasing the understanding on schistosomiasis mansoni, improving the awareness toward schistosomiasis mansoni prevention and control, and identifying, reporting and managing imported cases with S. mansoni infection or pathogen carriers, are of particular importance to prevent the development of entire life cycle of S. mansoni and the resultant schistosomiasis mansoni transmission in China. To protect public health, a consensus has been reached pertaining to the surveillance and control strategy of imported schistosomiasis mansoni by Chinese infectious disease experts and parasitologists, with aims to improve the awareness and capability for the diagnosis, treatment and control of imported schistosomiasis mansoni among Chinese disease control and prevention institutions and medical institutions, and decrease and even eliminate the risk of schistosomiasis mansoni transmission in China.

Study on biological characteristics: reproduction and viability of Biomphalaria glabrata as an intermediate host of Schistosoma mansoni / 中国血吸虫病防治杂志

Objective To compare the difference of fertility of Biomphalaria glabrata snails between self-fertilization and cross-fertilization and to observe the circadian rhythm of laying eggs, the effect of light on laying eggs and the tolerance of the snail to water and food deficiency, so as to provide the evidence for control and elimination of B. glabrata snails in the field. Methods Under laboratory conditions, a single B. glabrata egg for self-fertilization was separated and hatched individually, and young snails were raised in different plastic boxes individually. The eggs for cross-fertilization were hatched and the young snails were fed in the same plastic box. The ability of spawn, the development of the eggs, and the number of snails growing from young to adult snails were compared between the self-fertilization and cross-fertilization. The snails were in the water under four environments, all day illumination, all day without illumination, daytime lighting and night without illumination, and daytime without illumination but night lighting. The eggs were collected and counted daily. The circadian rhythm of spawn and the effect of illumination on spawn were observed. The adult snails were divided into 6 groups and exposed to the environments with relative humidity of 0, 65%, 87% and 100%, respectively. The survival rates of the adult snails exposed to the different environments after different time were observed. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were observed. Results In the 25 °C water, the average laying egg number for 15 days per snail was (8.77 ± 16.92) eggs/snail in the self-fertilization snail. The average laying egg number for 15 days per snail was (149.71 ± 142.28) eggs/snail in the cross-fertilization snails. There was a significant difference between the self-fertilization snail and cross-fertilization snail (t = 0.999 999, P < 0.01). The hatching rate and reproductive maturation rate of the self-fertilization snails and cross-fertilization snails were 50.1% and 78.9%, and 19.3% and 3.8%, respectively, There was a significant difference (the hatching rate: χ2 = 18.18, P < 0.01, the reproductive maturation rate: χ2 = 11.83, P < 0.01) . In the natural environment of daytime with illumination and nighttime with darkness, the amount of laying 20 eggs of B. glabrata snail was (944.07 ± 392.53) eggs/day during a whole day, among them the amount of laying eggs during daytime account for 10.1% and the amount of laying eggs during nighttime account for 89.9%, and the laying egg was given priority to with the night. The above results suggested that the dark environment was conducive to B. glabrata snails to lay eggs. The above results suggested that light can promote the increase of spawning of B. glabrata. When B. glabrata was exposed to the environments with the relative humidity of 0, 65%, 87% and 100% at 25 °C, respectively, and the longest survival times of snails were 7, 70, 150 d and 100 d, respectively. In the 25 °C water, the snails could survive for 50 days without food. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were 100%, 100%, 100%, 100%, 70%, 30%, 0, 0, 0 and 0, respectively. Conclusions B. glabrata can achieve the reproductive process by cross-fertilization or self-fertilization. There is a significant difference in reproductive ability between the cross-fertilization snail and self-fertilization snail, cross-fertilization is stronger than self-fertilization, but the rate of reproduction in the self-fertilization is higher than that in the cross-fertilization. It is indicated that B. glabrata that survive after the dry season plays an important role in the maintenance of local snail populations and transmission of schistosomiasis mansoni.

Progress of research on biologically invasive medical molluscs in China / 中国血吸虫病防治杂志

Invasion of alien species has increasingly become a major environmental problem that damages human health, economic development and ecological security in China, which has been paid much attention. Until now, there have been 753 invasive species reported in China, and invasive medical molluscs include Pomacea canaliculata, Achatina fulica, and Biomphalaria straminea. This review summarizes the status of biologically invasive species in China, describes the species and distribution of invasive medical molluscs, analyzes the damages of the invasive medical molluscs-transmitted diseases, and proposes the preventive and control measures.

Surveillance and control strategy of imported schistosomiasis mansoni: an expert consensus / 中国血吸虫病防治杂志

In 1980s, Biomphalaria straminea, an intermediate host of Schistosoma mansoni, was found in Shenzhen City, Guangdong Province, China, and currently, this snail has colonized in Shenzhen City and spread to peripheral cities involving of Dongguan and Huizhou. Since imported cases infected with S. mamoni have been reported from time to time in China, Mainland China is facing the potential risk of transmission of schistosomiasis mansoni. With the deepening of the opening-up policy, notably the implementation of the Belt and Road Initiative, there is an increase in the risk of transmission of schistosomiasis mansoni in Mainland China. Increasing the understanding on schistosomiasis mansoni, improving the awareness toward schistosomiasis mansoni prevention and control, and identifying, reporting and managing imported cases with S. mansoni infection or pathogen carriers, are of particular importance to prevent the development of entire life cycle of S. mansoni and the resultant schistosomiasis mansoni transmission in China. To protect public health, a consensus has been reached pertaining to the surveillance and control strategy of imported schistosomiasis mansoni by Chinese infectious disease experts and parasitologists, with aims to improve the awareness and capability for the diagnosis, treatment and control of imported schistosomiasis mansoni among Chinese disease control and prevention institutions and medical institutions, and decrease and even eliminate the risk of schistosomiasis mansoni transmission in China.

Nanoemulsion containing essential oil from Xylopia ochrantha Mart. produces molluscicidal effects against different species of Biomphalaria (Schistosoma hosts)

BACKGROUND This work describes a chemical study of the essential oil from leaves of Xylopia ochrantha, an endemic Annonaceae species from Brazil, and its activity against Biomphalaria species. Considering its poor solubility in aqueous medium, the essential oil was nanoemulsified to evaluate its action on controlling some mollusc species of genus Biomphalaria, snail hosts of Schistosoma mansoni that causes schistosomiasis, which mainly affects tropical and subtropical countries. OBJECTIVES The main aims of this work were to analyse the chemical composition of essential oil from X. ochrantha, and to evaluate the effect of its nanoemulsion on molluscs of genus Biomphalaria and their oviposition. METHODS Chemical analysis was performed by gas chromatography coupled to mass spectrometry. Nanoemulsions were prepared by a low energy method and characterised by particle size and polydispersity index. Biological assays evaluating the mortality of adult species of B. glabrata, B. straminea and B. tenagophila and their ovipositions upon contact with the most stable nanoemulsion during 24 and 48 h were performed. FINDINGS Chemical analysis by mass spectrometry revealed the majority presence of bicyclogermacrene and germacrene D in the essential oil. The formulation with a hydrophilic-lipophilic balance (HLB) of 9.26 was the most suitable for the oil delivery system. This nanoemulsion caused the mortality in B. tenagophila, B. straminea and B. glabarata of different sizes at levels ranging from 50 to 100% in 48 h. Additionally, the formulation could inhibit the development of deposited eggs. CONCLUSION Thus, these results suggest the use of nanoemulsified essential oil from X. ochrantha as a possible alternative in controlling some Biomphalaria species involved in the schistosomiasis cycle.

Prevalence of infection of biomphalaria glabrata by schistosoma mansoni and the risk of urban schistosomiasis mansoni in Salvador, Bahia, Brazil

Abstract INTRODUCTION: Biomphalaria glabrata is considered to be responsible for the incidence of schistosomiasis in Brazil. Therefore, surveillance of areas where schistosomiasis is prevalent is fundamental for public health planning. This study was aimed to evaluate B. glabrata populations in water bodies of the city of Salvador, determine their distribution, estimate the prevalence of Schistosoma mansoni infections, characterize shed cercariae, and identify transmission foci. METHODS: Malacological surveys were carried out in 17 water collections from Salvador. Snail species were identified based on shell and mantle characteristics. Snails were evaluated for S. mansoni infection by exposure to light and via real time polymerase chain reaction (qPCR) using S. mansoni-18S rRNA subunit specific primers. RESULTS: 1,403 B. glabrata were collected. Classical cercarial shedding indicated that 5 snails (0.4%) were positive for S. mansoni. A higher prevalence of infections was found in Horta de Saramandaia (5.5%) and Lagoa do IAT (1.9%). Non-Schistosoma larvae, such as Xiphidiocercaria, Strigeidae, Spirorchiidae and Clinostomidae, were observed in 3.2% of the snails. S. mansoni DNA was detected in 6.2% snails via qPCR. CONCLUSIONS: B. glabrata is widely distributed in Salvador, as indicated by 7 water collections associated with a risk of schistosomiasis transmission. To our knowledge, this is the first study to identify B. glabrata eliminating cercariae of Clinostomidae, Strigeidae, and Spirorchiidae in Salvador. We propose that qPCR may be employed in combination with classical cercarial shedding. Estimating S. mansoni prevalence in snails by only considering the results of light exposure method classical into account may underestimate the problem.

Diversity of Biomphalaria spp. freshwater snails and associated mollusks in areas with schistosomiasis risk, using molecular and spatial analysis tools / Diversidade de caramujos de água doce Biomphalaria spp. e outros moluscos associados, em áreas de risco da esquistossomose, empregando ferramentas moleculares e espaciais

Abstract: The Middle Paranapanema River region of São Paulo, Brazil is home to significant diversity of Biomphalaria species and is very vulnerable to health and environmental impacts such as schistosomiasis. This study updates freshwater malacological surveys for ecosystems in one portion of the Middle Paranapanema River Basin, with emphasis on the genus Biomphalaria. Snails were collected from 114 distinct bodies of water between 2015 and 2018. Biomphalaria specimens were identified according to morphological and molecular characteristics, while animals in other genera (Drepanotrema, Lymnaea, Melanoides, Physa and Pomacea) were identified solely according to shell characteristics. A geographic information system was used to update intermediate host colonization sites and consequently assist in identifying probable hotspots for intermediate hosts of schistosomiasis. The sequences of the COI gene relating to the DNA barcode stretch were tested for similarity against sequences found in GenBank, for monophyly through Maximum Likelihood phylogenetic inference, and analyzed in ABDG, bPTP and GMYC for the delimitation of putative species. Of the 10,722 snails collected, 86.7% were in the Planorbidae family (75.5% Biomphalaria and 11.2% Drepanotrema) and 13.3% were other non-Planorbidae species (Lymnaea, Melanoides, Physa and Pomacea). The taxonomic COI reference sequences in the NCBI nucleotide database used for DNA sequence comparison, and phylogenetic analysis used to test the monophyly of the groups, resulted in more reliable taxonomic units than delimitation of the COI sequences in MOTUs using statistical taxonomic models. Analysis of the species distribution shows that B. glabrata and B. tenagophila are heterogeneously distributed in the study area. B. glabrata colonizes only five water bodies, in the study area, most of them in Ourinhos, while B. tenagophila predominates in water bodies in Ipaussu. Contrasting with this, B. straminea, B. occidentalis and B. peregrina are evenly distributed throughout the study area.

Resumo: A região do Médio Rio Paranapanema, em São Paulo, Brasil abriga uma diversidade significativa das espécies de Biomphalaria. É também uma região vulnerável a impactos ambientais e de saúde, como a esquistossomose. Este estudo atualiza dados sobre a distribuição de caramujos de água doce em ecossistemas de uma porção da Bacia do Médio Rio Paranapanema, com ênfase no gênero Biomphalaria. Os caramujos foram coletados de 114 corpos distintos de água doce, entre 2015 e 2018. Exemplares pertencentes ao gênero Biomphalaria foram identificados de acordo com características morfológicas e moleculares, enquanto animais de outros gêneros (Drepanotrema, Lymnaea, Melanoides, Physa e Pomacea) foram identificados somente de acordo com características da concha. Ferramentas de análise geoespaciais foram utilizadas para atualizar os sítios de colonização dos caramujos e, consequentemente, auxiliar na identificação de possíveis pontos críticos para hospedeiros intermediários da esquistossomose. As sequências do gene COI relacionadas ao DNA barcode foram testadas quanto à similaridade com sequências encontradas no GenBank, por análise filogenética sob maxima verossimilhança, e analisadas em ABDG, bPTP e GMYC para a delimitação de espécies putativas. Dos 10.722 moluscos coletados, 86,7% pertenciam a família Planorbidae (75,5% Biomphalaria e 11,2% Drepanotrema) e 13,3% a Lymnaea spp., Melanoides spp., Physa spp. e Pomacea spp. A comparação das sequências taxonômicas de COI com o banco de dados de nucleotídeos do NCBI, e a análise filogenética usada para testar a monofilia dos grupos, resultaram em delimitações taxonômicas comparáveis à delimitação morfológica. As espécies B. glabrata e B. tenagophila estão heterogeneamente distribuídas ao longo da área de estudo. B. glabrata foi identificada em apenas cinco coleções de água doce, quatro delas em Ourinhos, enquanto B. tenagophila predominou em Ipaussu. Por outro lado, B. straminea, B. occidentalis e B. peregrina estão distribuídas uniformemente na área de estudo.