Efeito moluscicida do óleo essencial de Cymbopogon winterianus Jowitt (Poaceae) sobre Lymnaea columella (Say, 1817) e Biomphalaria tenagophila (D'Orbigny, 1835) / Molluscicidal effect of essential oil of Cymbopogon winterianus Jowitt (Poaceae) on Lymnaea columella (Say, 1817) and Biomphalaria tenagophila (D'Orbigny, 1835)

RESUMO O uso das substâncias moluscicidas convencionais no controle de planorbídeos vetores constitui-se uma importante ferramenta no combate da fasciolose hepática e esquistossomose. Sendo, portanto, de extrema relevância para a pecuária e para os serviços de Vigilância Epidemiológica. Por outro lado, a seleção de caramujos resistentes a tais substâncias e sua baixa seletividade estimulam a busca por novas substâncias. Neste sentido, o presente trabalho foi desenvolvido para avaliar o efeito do óleo essencial de Cymbopogon winterianusJowitt sobre Lymnaea columella e Biomphalaria tenagophila, hospedeiros intermediários de Fasciola hepatica e esquistossomose mansônica, respectivamente. O óleo essencial foi extraído a partir de folhas frescas utilizando o sistema Clevenger. A análise qualitativa foi realizada por meio de cromatografia gasosa acoplada a espectrometria de massas (CG/EM) e a quantificação dos constituintes presentes no óleo foi determinada por cromatografia gasosa acoplada ao detector de ionização de chama (CG/DIC). O efeito moluscicida foi avaliado utilizando seis moluscos de cada espécie e o óleo essencial de C. winterianus nas concentrações finais de 10, 20, 30, 40, 60, 80 e 100 ppm. A análise por cromatografia gasosa do óleo essencial possibilitou a identificação dos componentes majoritários geraniol (28,62%), citronelal (23,62%) e citronelol (17,10%). Os valores de DL100 e DL50para os moluscos das espécies L. columella e B. tenagophila foram, respectivamente, 60 e 40 ppm; 80 ppm e 60 ppm. O óleo de Cymbopogon winterianus demonstrou-se uma alternativa promissora para o controle dos moluscos, sendo a espécie L. columella mais sensível ao mesmo.

ABSTRACT Conventional molluscicides have been employed to control of planorbids vectors and are an important tool in order to control the hepatic fascioliasis and schistosomiasis. Thus, these substances have been showinggreat relevance for both Veterinary and Livestock Services as well as for Epidemiology and Disease Surveillance. On the other hand, the process of drug pressure for the selection of resistant snails to such components and their low selectivity have stimulated the search for new substances. Since researches on new drugs are the starting point to assist on themolluscs control, this work was developed in order to evaluate the effect of Cymbopogon winterianus Jowitt essential oil on L. columella and B. tenagophila, intermediate hosts of Fasciola hepatica and Schistosoma mansoni, respectively. The essential oil was obtained from fresh leaves by hydrodistillation using a Clevenger apparatus. A qualitative analysis was performed by gas chromatography together with a mass spectrometry one (GC/MS) and the chemical constituent content was determined by gas chromatography with a flame ionization detector (GC/FID). The molluscicidal effect was evaluated through the use of six snails of each species and C. winterianus essential oil at 10, 20, 30, 40, 60, 80 and 100 ppm. The result of the gas chromatographic analysis for the essential oil showed geraniol (28.62%), citronellal (23.62%) and citronellol (17.10%) as the major chemical components . The DL100 and DL50 values for L. columella and B. tenagophila species were, respectively, 60 and 40 ppm; 80 ppm and 60 ppm. L. columella had demonstrated more sensitivity to this essential oil than theB. tenagophila species. The C. winterianus essential oil proved to be a promising alternative for the control of these molluscs being the L. columella species the most sensitive of them.

Biology of Kalipharynx sp. (Trematoda: Digenea) metacercariae in Biomphalaria (Gasteropoda: Planorbidae) from Northeastern Argentina / Biología de metacercarias Kalipharynx sp. (Trematoda: Digenea) en Biomphalaria (Gasteropoda: Planorbidae) del noreste argentino

In Argentina, no ecological studies have been reported on the infection parameters of Kalipharynx sp. metacercariae in planorbid snails. To this end, the aims of this study were: (i) to provide information on the population biology of Kalipharynx sp. metacercariae in the planorbid snails Biomphalaria tenagophila and B. occidentalis through the study of prevalence and intensity of larval infection during a seasonal cycle; (ii) to evaluate the effects of host shell size on prevalence and infection intensity, (iii) to evaluate the effect of infection intensity on cyst size. Samples were taken between June 2010 and April 2011 (encompassing all seasons) from a subtropical permanent pond in Corrientes City, Corrientes, Argentina. A total of 362 metacercariae (n=262 and n=100; from B. tenagophila and B. occidentalis respectively) were collected from 616 snails (n=466 and n=150 from B. tenagophila and B. occidentalis respectively). The metacercarial cysts were found in the digestive gland, mantle cavity, intestine and ovotestis. B. tenagophila showed a range of infection from 1 to 60 cysts per snail (mean=4.5±SD=9.9), and cyst diameter ranging between 255 and 705μm (466.4±119); while, B. occidentalis showed a range of infection from 1 to 23 (5.5±5.6), and cyst diameter ranging between 310 to 900μm (554.5±150). Results obtained indicated that, although absent in autumn, metacercariae of Kalipharynx sp. were present most of the year in both species of Biomphalaria, showing high values in both warm-season. Furthermore, both the infection intensity and host shell size varied significantly between seasons, although no seasonal variation was observed with respect to metacercarial cyst size, suggesting the possibility of more than one peak of cercariae emergence during the year. The prevalence of infection was significantly and positively correlated with snail size in both host species (p<0.05). The smallest host size class harbouring a metacercarial infection was 7.1-8.0mm and 11.1-12.0mm in B. tenagophila and B. occidentalis, respectively. The mean intensity of infection was positively correlated with snail size, but this relation was significant only in B. tenagophila (p<0.05). However, non-significant negative correlations were observed for intensity of infection vs cyst size in both host species (p>0.05). The results of this study show a significant influence of host size on prevalence and infection intensity, and a tendency towards density-dependent reductions in the growth of cysts. This is the first study in Argentina analyzing the population biology of Kalipharynx sp. metacercariae.Rev. Biol. Trop. 61 (4): 1647-1656. Epub 2013 December 01.

En Argentina, no hay estudios ecológicos que hayan reportado los parámetros de infección de metacercarias Kalipharynx sp. en caracoles planorbídeos. Por lo que los objetivos de este estudio fueron: (i) proporcionar información sobre la biología de la población de metacercarias Kalipharynx sp. en los planorbídeos Biomphalaria tenagophila y B. occidentalis, a través del estudio de la prevalencia e intensidad de la infección por larvas durante un ciclo estacional, (ii) evaluar los efectos del tamaño del hospedador sobre la prevalencia y la intensidad de la infección (iii) evaluar el efecto de la intensidad de infección sobre el tamaño del quiste. Entre junio 2010 y abril 2011 se recolectaron en una laguna semipermanente de Corrientes, Argentina, un total de 616 caracoles (n=466 y n=150 de B. tenagophila y B. occidentalis, respectivamente) de los cuales se extrajeron 362 metacercarias (n=262 y n=100; de B. tenagophila y B. occidentalis, respectivamente). Se encontraron quistes en glándula digestiva, cavidad del manto, intestino y ovotestis. B. tenagophila y B. occidentalis estuvieron infectados con metacercarias la mayor parte del año, excepto en otoño, con valores altos en las estaciones cálidas (primavera-verano). La intensidad de infección y el tamaño del hospedador mostraron diferencias significativas entre las tres estaciones analizadas (invierno-verano), aunque no se observaron variaciones estacionales con respecto al tamaño de los quistes, sugiriendo la posibilidad de más de un pico de emergencia de las cercarias durante el año. La prevalencia se correlacionó positiva y significativamente con el tamaño del hospedador en ambas especies (p<0.05). La intensidad media de infección se correlacionó positivamente con el tamaño del hospedador, pero esta relación fue significativa sólo en B. tenagophila (p<0.05). Sin embargo, se observaron correlaciones negativas no significativas entre la intensidad de infección y el tamaño de los quistes en ambas especies (p>0.05). Los resultados obtenidos muestran una influencia significativa del tamaño del hospedador sobre la prevalencia y la intensidad de infección y una tendencia hacia reducciones denso-dependientes en el crecimiento de los quistes. Es el primer estudio que analiza la biología poblacional de metacercarias Kalipharynx sp. en caracoles planorbídeos de Argentina.

Susceptibility of Argentinean Biomphalaria tenagophila and Biomphalaria straminea to infection by Schistosoma mansoni and the possibility of geographic expansion of mansoni schistosomiasis

Introduction Human migration and the presence of natural vectors (mollusks) of Schistosoma mansoni are the primary causes of the expansion of mansoni schistosomiasis into southern areas of South America. Water conditions are favorable for the expansion of this disease because of the extensive hydrographic network, which includes the basins of the Paraná and Uruguay rivers and favors mollusk reproduction. These rivers also aid agriculture and tourism in the area. Despite these favorable conditions, natural infection by S. mansoni has not yet been reported in Argentina, Uruguay, or Paraguay. Methods Two species of planorbid from Argentina, Biomphalaria straminea and B. tenagophila, were exposed to the miracidia of five Brazilian strains of S. mansoni. Results Biomphalaria tenagophila (Atalaya, Buenos Aires province) was infected with the SJS strain (infection rate 3.3%), confirming the experimental susceptibility of this Argentinian species. Biomphalaria straminea (Rio Santa Lucía, Corrientes province) was susceptible to two Brazilian strains: SJS (infection rate 6.7%) and Sergipe (infection rate 6.7%). Conclusions These results demonstrate that species from Argentina have the potential to be natural hosts of S. mansoni and that the appearance of foci of mansoni schistosomiasis in Argentina is possible. .

Schistosomiasis mansoni in urban Northeast Brazil: influence of rainfall regime on the population dynamics of Biomphalaria sp.

Introduction Our objective was to evaluate the influence of rainfall regime on the population dynamics of Biomphalaria in a potential urban focus of schistosomiasis in Aracaju, Brazil, during 2009-2010. Methods Snails were collected monthly and were counted, measured and identified; the level of infection and fecal contamination at the sampling sites was determined; rainfall data were obtained. Results High levels of fecal contamination were observed, and the abundance of Biomphalaria glabrata increased during the rainy and post-rainy seasons. The snails' size was variable, and infected snails were identified independently of rainfall. Conclusions These results provide evidence of anthropogenic and climate interference in an urban focus of schistosomiasis in the Aracaju metropolitan area. .

The Pampulha reservoir remains a potential urban focus of schistosomiasis mansoni in Brazil: changes in the occurrence patterns of Biomphalaria species and a new record of the parasite

Introduction The Pampulha reservoir has long been a focus of schistosomiasis transmission in Belo Horizonte, State of Minas Gerais, Brazil. The last malacological study conducted in this urban reservoir was more than two decades ago, and thus, an update on the distribution of the species of Biomphalaria as well as new data on the presence of Schistosoma mansoni in this water body are required. Methods The current distribution of Biomphalaria spp. in the Pampulha reservoir and their infection with S. mansoni was evaluated during 55 malacological surveys conducted between 2009 and 2012. Results Biomphalaria straminea displayed a high population density and distribution, and 13.7% (2,233/16,235) of the specimens collected were infected with larval trematodes other than Schistosoma mansoni. Biomphalaria tenagophila and Biomphalaria glabrata, species currently presenting a restricted distribution and small populations, displayed trematode infection rates of 15.2% (98/644) and 13% (83/640), respectively. Thirteen (2%) specimens of B. glabrata were found to be infected with S. mansoni. In addition, a historical review based on previous and new data on the occurrence patterns of Biomphalaria species in this reservoir is presented. Conclusions The results indicate that the Pampulha reservoir remains a potential focus of urban schistosomiasis in Brazil, and significant changes in the occurrence patterns of Biomphalaria species were verified. .

ocorrência de moluscos do gênero Biomphalaria em parques da cidade de Belo Horizonte, Minas Gerais, Brasil / Occurrence of mollusks, genus Biomphalaria, in parks of the city of Belo Horizonte, Minas Gerais, Brazil

Até pouco tempo a esquistossomose era considerada a mais prevalente endemia entre a população rural de baixa renda, especialmente nos estados do Nordeste e Sudeste do Brasil, sendo por issoclassificada como endemia rural. Estudos recentes têm demonstrado que o perfil epidemiológico desta doença está mudando, uma vez que vem sendo transmitida nas periferias e mesmo dentro de grandes centros urbanos. A cidade de Belo Horizonte-MG tem 71 parques, dos quais 55 são abertos àvisitação pública. Em 31 (43,6por cento) deles há uma ou mais coleções hídricas. O objetivo deste trabalhofoi investigar a presença de moluscos de importância médica nas coleções hídricas destes 31 parques da capital mineira. Foram coletados, em 11 parques, 551 exemplares de Biomphalaria, hospedeiraintermediária do Schistosoma mansoni. Foram também coletados exemplares dos gêneros Drepanotrema sp, Pomacea sp, Melanoides sp, Physa sp e Lymnaea sp, este último hospedeirointermediário de outro parasito causador da fasciolose. Todos os exemplares se mostraram negativos para cercárias de S. mansoni. No entanto, considerando a possível contaminação do meio ambiente com fezes humanas infectadas com ovos de S. mansoni e a presença dos hospedeirosintermediários, estes achados servem de alerta para uma possível instalação do ciclo de transmissão da esquistossomose em parques municipais da cidade de Belo Horizonte.

Hybridism between Biomphalaria cousini and Biomphalaria amazonica and its susceptibility to Schistosoma mansoni

Molecular techniques can aid in the classification of Biomphalaria species because morphological differentiation between these species is difficult. Previous studies using phylogeny, morphological and molecular taxonomy showed that some populations studied were Biomphalaria cousini instead of Biomphalaria amazonica. Three different molecular profiles were observed that enabled the separation of B. amazonica from B. cousini. The third profile showed an association between the two and suggested the possibility of hybrids between them. Therefore, the aim of this work was to investigate the hybridism between B. cousini and B. amazonica and to verify if the hybrids are susceptible to Schistosoma mansoni. Crosses using the albinism factor as a genetic marker were performed, with pigmented B. cousini and albino B. amazonica snails identified by polymerase chain reaction-restriction fragment length polymorphism. This procedure was conducted using B. cousini and B. amazonica of the type locality accordingly to Paraense, 1966. In addition, susceptibility studies were performed using snails obtained from the crosses (hybrids) and three S. mansoni strains (LE, SJ, AL). The crosses between B. amazonica and B. cousini confirmed the occurrence of hybrids. Moreover, hybrids can be considered potential hosts of S. mansoni because they are susceptible to LE, SJ and AL strains (4.4 percent, 5.6 percent and 2.2 percent, respectively). These results indicate that there is a risk of introducing schistosomiasis mansoni into new areas.

Malacological survey of Biomphalaria snails in municipalities along the Estrada Real in the southeast of the State of Minas Gerais, Brazil / Pesquisa malacológica de Biomphalaria em municípios da Estrada Real, situados no sudeste do Estado de Minas Gerais

INTRODUCTION: The increasing practice of ecotourism and rural tourism in the State of Minas Gerais, Brazil, highlights the importance of studies concerning the occurrence of potential intermediate hosts of Schistosoma mansoni. This study aimed to identify species of Biomphalaria snails in municipalities along the Estrada Real, an important Brazilian tourism project. METHODS: The specimens were collected in different water collections of 36 municipalities along the Estrada Real in the southeast of the State of Minas Gerais. Biomphalaria species were characterized using both morphological and molecular approaches. The research was conducted between August 2005 and September 2009 and all the sites visited were georeferenced using GPS. RESULTS: Six Biomphalaria species were found in 30 of the 36 municipalities studied: glabrata, tenagophila, straminea, peregrina, occidentalis and schrammi. The first three species of Biomphalaria, recognized as intermediate hosts of S. mansoni, were present in 33.3 percent, 47.2 percent and 8.3 percent of the municipalities studied, respectively. The mollusks were found in different types of water collections and no infection by S. mansoni was detected. The highest occurrence of Biomphalaria concentration was verified in the area covered by the Caminho Novo route (Diamantina/MG to Rio de Janeiro/RJ). CONCLUSIONS: Considering the occurrence of schistosomiasis in the State of Minas Gerais and the socioeconomic repercussions involved in the Estrada Real Project, this work focuses on the vulnerability of water collections due to the presence of Biomphalaria mollusks and emphasizes the need for epidemiological surveillance and sanitary and educational measures integrated with the local community and tourism sectors.

INTRODUÇÃO: O aumento das práticas de ecoturismo e turismo rural, em Minas Gerais, Brasil, evidencia a importância de se realizarem estudos sobre a ocorrência de hospedeiros intermediários do Schistosoma mansoni, no estado. O presente trabalho objetivou a busca e identificação das espécies de caramujos Biomphalaria encontrados em municípios mineiros pertencentes à Estrada Real, um importante projeto de turismo brasileiro. MÉTODOS: Os moluscos foram coletados em 36 municípios da Estrada Real, no sudeste de Minas Gerais. A pesquisa foi realizada de agosto de 2005 a setembro de 2009 e todos os locais visitados foram georreferenciados com o uso de GPS. RESULTADOS: Dos 36 municípios estudados, 30 apresentaram a ocorrência de pelo menos uma entre as seis espécies de Biomphalaria: glabrata, tenagophila, straminea, peregrina, occidentalis e schrammi. As três primeiras espécies citadas, reconhecidas como hospedeiras intermediárias do S. mansoni, estavam presentes em 33,3 por cento, 47,2 por cento e 8,3 por cento dos municípios estudados, respectivamente. Os moluscos foram encontrados em diferentes tipos de coleções hídricas e em nenhum deles foi detectada infecção pelo S. mansoni. Houve maior ocorrência de Biomphalaria na área referente ao Caminho Novo (Diamantina/MG ao Rio de Janeiro/RJ). CONCLUSÕES: Considerando-se a ocorrência da esquistossomose, no Estado de Minas Gerais, e as repercussões socioeconômicas que envolvem o projeto Estrada Real, este trabalho aponta para a vulnerabilidade das coleções hídricas devido à presença de moluscos Biomphalaria e enfatiza a necessidade de vigilância epidemiológica e medidas educativas e sanitárias integradas com a comunidade local e setores de turismo.

Distribution and habitat preferences of the genus Biomphalaria (Gastropoda: Planorbidae) in Cuba

A study was carried out to determine the distribution and habitat preferences of several species of the genus Biomphalaria. Samples were taken at 350 freshwater locations in Cuba. Three species of Biomphalaria (Biomphalaria havanensis, Biomphalaria helophila and Biomphalaria pallida) were recorded based on their distribution. Of the three species, B. havanensis has the weakest distribution because it was identified in only one locality. The other species, B. helophila and B. pallida, are abundant in rivers and dams and have large populations in Cuba. However, the only species that appears to occur in ecosystems shared with thiarids is B. pallida, possibly due to recent introduction of thiarids, but always in fewer numbers. Here we discuss the possibility of these species to act as intermediary hosts of Schistosoma mansoni in Cuba over the basis of occurrence in natural and anthropic habitats.

Biomphalaria molluscs (Gastropoda: Planorbidae) in Rio Grande do Sul, Brazil

The present study was aimed at characterising Biomphalaria species using both morphological and molecular (PCR-RFLP) approaches. The specimens were collected in 15 localities in 12 municipalities of the southern region of the state of Rio Grande do Sul, Brazil. The following species were found and identified: Biomphalaria tenagophila guaibensis, Biomphalaria oligoza and Biomphalaria peregrina. Specimens of the latter species were experimentally challenged with the LE Schistosoma mansoni strain, which showed to be refractory to infection.

Avaliação de medidas de controle da esquistossomose mansoni no Município de Sabará, Minas Gerais, Brasil, 1980-2007 / Evaluation of schistosomiasis mansoni control measures in Sabará, Minas Gerais State, Brazil, 1980-2007

Schistosomiasis control programs in Brazil have helped reduce prevalence and the severe forms of the disease, but have failed to prevent new foci from appearing, especially on the periphery of large cities. The current article aims to assess the prevalence of schistosomiasis and the presence of intermediates hosts for Schistosoma mansoni in the district of Ravena, Municipality of Sabará, Minas Gerais State, Brazil, 27 years after implementing water treatment and specific treatment for infected individuals. Ravena responded positively to schistosomiasis control measures, with a prevalence of 2.5%. However, the district remains a potential risk area, since it displays favorable environmental and ecological factors for maintenance of the disease. For the prevalence rates to continue low, it will be necessary to invest in sanitation and health education, in addition to treatment of infected individuals.

Os programas de controle da esquistossomose no Brasil têm contribuído para a redução da prevalência e das formas graves da doença, mas não têm impedido que novos focos apareçam, especialmente nas áreas periféricas dos grandes centros urbanos do país. O presente artigo tem como objetivo avaliar a prevalência da esquistossomose e a presença de hospedeiros intermediários do Schistosoma mansoni no distrito de Ravena, Município de Sabará, Minas Gerais, Brasil, após 27 anos da implantação do sistema de água tratada e do tratamento específico da população infectada. Ravena apresentou uma resposta positiva às intervenções de controle da esquistossomose, apresentando uma prevalência de 2,5%. Porém, é uma área de risco em potencial, pois apresenta fatores ambientais e ecológicos favoráveis à manutenção da doença. Para que os níveis de prevalência continuem baixos, será necessário investir em saneamento, educação em saúde além de tratamento dos infectados.

Efeitos da implantação da Usina Hidrelétrica de Rosal, Rio Itabapoana, Estados do Espírito Santo e Rio de Janeiro, sobre anofelinos, planorbídeos e flebotomíneos / Effects of the installation of the Rosal hydroelectric power station, Itabapoana River, States of Espírito Santo and Rio de Janeiro, on anophelinae, planorbidae and phlebotominae

A construção de represas geralmente causa modificações na composição da fauna em sua área de influência. Na área de implantação da Usina Hidrelétrica de Rosal, Estados do Espírito Santo e Rio de Janeiro, foram avaliadas modificações na abundância de anofelinos, planorbídeos e flebotomíneos antes (1998-2000) e após (2000-2005) o represamento. Foram definidos nove pontos de coleta, cada qual representado por uma moradia e seus anexos, abrigos de animais domésticos e coleções hídricas num raio de 150m. Coletaram-se 103 anofelinos adultos antes do represamento e 313 depois, 200 imaturos antes e 708 depois, 868 planorbídeos antes e 486 depois, e 2.979 flebotomíneos antes e 912 depois. O registro de vetores dentre anofelinos, planorbídeos e flebotomíneos revela o potencial da área para transmissão de malária, esquistossomose e leishmaniose tegumentar. As transformações ambientais ocorridas, no entanto, não aumentaram o risco para ocorrência dessas doenças.

The construction of dams usually changes the composition of the fauna within their areas of influence. In the area where the Rosal hydroelectric power station has been installed, in the States of Espírito Santo and Rio de Janeiro, changes to the abundance of anophelinae, planorbidae and phlebotominae were evaluated before (1998-2000) and after (2000-2005) the damming. Nine sample collection points were defined, each represented by a home and its outbuildings, shelters for domestic animals and water collection points within a radius of 150m. One hundred and three adult anophelinae were collected before the damming and 313 afterwards; 200 immature anophelinae before and 708 afterwards; 868 planorbidae before and 486 afterwards; and 2,979 phlebotominae before and 912 afterwards. The vector record, consisting of anophelinae, planorbidae and phlebotominae, shows the potential of this area for transmission of malaria, schistosomiasis and American cutaneous leishmaniasis. However, the environmental changes did not increase the risk of the occurrence of these diseases.

Occurrence of Naididae (Annelida: Oligochaeta) from three gastropod species in irrigation fields in southeastern Brazil / Ocorrência de Naididae (Annelida: Oligochaeta) em três espécies de gastrópodes em campos irrigados no sudeste do Brasil

In the present study we report the occurrence of three Naididae species from three gastropod mollusk species. The species Dero (Dero) righii was found from mollusks of the genus Biomphalaria. Nais communis was found from Biomphalaria sp. and Aplexa rivalis. Chaetogaster limnaei was found from Biomphalaria sp., Aplexa rivalis and Lymnaea columella. In Brazil, previous studies have reported the occurrence of Chaetogaster limnaei from Biomphalaria solely, while Nais communis have been found from Pomacea bridgesii and Dero (Dero) righii in the sediment of aquatic habitats in Mato Grosso do Sul. Our results indicate that, due to their locomotion, naidids are capable of colonizing different substrates in aquatic environments.

No presente estudo, relatamos a ocorrência de Dero (Dero) righii associada a moluscos do gênero Biomphalaria. Nais communis foi encontrada associada a Biomphalaria sp. e Aplexa rivalis. A espécie Chaetogaster limnaei esteve associada à Biomphalaria sp., Aplexa rivalis e Lymnaea columella. No Brasil, estudos anteriores registraram Chaetogaster limnaei associada somente à Biomphalaria, Nais communis à Pomacea bridgesii e Dero (Dero) righii ao sedimento de ambientes aquáticos no Mato Grosso do Sul. Os resultados obtidos confirmam que, devido à capacidade de se deslocar na coluna d'água, os oligoquetos naidideos apresentam habilidade de colonizar diferentes substratos presentes nos ambientes aquáticos.

Biomphalaria tenagophila potencial vector of Schistosoma mansoni in the Paraná River basin (Argentina and Paraguay)

Susceptibility and compatibility experiments were carried out with 700 Biomphalaria tenagophila from the Paraná River basin exposed to infection with Schistosoma mansoni. Individual infection was performed with 10 miracidia of SJ2 strain from the Paraiba valley (Brazil) originally infective to B. tenagophila. These snails were laboratory-breed progeny of B. tenagophila collected from six localities of Argentina and one from Paraguay. From Argentina: Rincón de Vences (7 percent) and Posadas (11 percent) became infected with S. mansoni and the calculation of Frandsen's index (TCP/100) shows that they were Class II poorly compatible. Those snails from Goya (22 percent), Maloyas (5 percent), and Berón de Astrada (3 percent) were Class III compatible to the S. mansoni. None of the 100 snails exposed from Caá-Catí became infected (Class 0 incompatible). Tested samples from Paraguay (Encarnación) were infected (20 percent) and compatible (Class III). It was also studied the persistence of the infection in 244 snails of the first generation (F1) of those that were susceptible from three places. It was demonstrated an increment of the susceptibility in the F1 from Maloyas (chi2 = 27.22; p = 0.0001) and Posadas (chi2 = 4.24; p = 0.04). The results point out the possibility that schistosomiasis might be able to spread into the Paraná River basin where B. tenagophila exists.

The Afro-American Biomphalariae

The reports on the occurrence of African planorbids in South America and of South American species in Africa and Asia are reviewed.

A bacterial artificial chromosome library for Biomphalaria glabrata, intermediate snail host of Schistosoma mansoni

To provide a novel resource for analysis of the genome of Biomphalaria glabrata, members of the international Biomphalaria glabrata Genome Initiative (biology.unm.edu/biomphalaria-genome.html), working with the Arizona Genomics Institute (AGI) and supported by the National Human Genome Research Institute (NHGRI), produced a high quality bacterial artificial chromosome (BAC) library. The BB02 strain B. glabrata, a field isolate (Belo Horizonte, Minas Gerais, Brasil) that is susceptible to several strains of Schistosoma mansoni, was selfed for two generations to reduce haplotype diversity in the offspring. High molecular weight DNA was isolated from ovotestes of 40 snails, partially digested with HindIII, and ligated into pAGIBAC1 vector. The resulting B. glabrata BAC library (BG_BBa) consists of 61824 clones (136.3 kb average insert size) and provides 9.05 × coverage of the 931 Mb genome. Probing with single/low copy number genes from B. glabrata and fingerprinting of selected BAC clones indicated that the BAC library sufficiently represents the gene complement. BAC end sequence data (514 reads, 299860 nt) indicated that the genome of B. glabrata contains ~ 63 percent AT, and disclosed several novel genes, transposable elements, and groups of high frequency sequence elements. This BG_BBa BAC library, available from AGI at cost to the research community, gains in relevance because BB02 strain B. glabrata is targeted whole genome sequencing by NHGRI.

Biomphalaria spp. (Preston, 1910) snails in the municipality of Juiz de Fora, Zona da Mata Mineira mesoregion, ate of Minas Gerais, Brazil

This study focuses on the geographic distribution of the snail of the genus Biomphalaria and evaluates its infectivity by Schistosoma mansoni in 5264 specimens collected in the municipality of Juiz de Fora, Minas Gerais, Brazil. Of the 31 locations studied, 6 were reservoirs, 11 rudimentary holding ponds, 7 irrigation ditches, 5 lakes, 1 ornamental pond, and 1 waterfall. Intermediate hosts were found only in the rudimentary ponds and ditches, which were 100 percent positive. Using morphological and molecular analysis techniques, B. tenagophila, B. peregrina, and B. straminea were identified. This is the first report of B. stramínea in the municipality, and evaluation of its infective potential revealed susceptibility of 25.4 percent. Although we did not find specimens of Biomphalaria infected by S. mansoni, the data obtained indicate the presence of intermediate hosts, especially in the irrigation ditches in Juiz de Fora, and their proximity to contaminated areas.

Differential lectin labelling of circulating hemocytes from Biomphalaria glabrata and Biomphalaria tenagophila resistant or susceptible to Schistosoma mansoni infection

Lectins/carbohydrate binding can be involved in the Schistosoma mansoni recognition and activation of the Biomphalaria hemocytes. Therefore, expression of lectin ligands on Biomphalaria hemocytes would be associated with snail resistance against S. mansoni infection. To test this hypothesis, circulating hemocytes were isolated from B. glabrata BH (snail strain highy susceptible to S. mansoni), B. tenagophila Cabo Frio (moderate susceptibility), and B. tenagophila Taim (completely resistant strains), labelled with FITC conjugated lectins (ConA, PNA, SBA, and WGA) and analyzed under fluorescence microscopy. The results demonstrated that although lectin-labelled hemocytes were detected in hemolymph of all snail species tested, circulating hemocytes from both strains of B. tenagophila showed a larger number of lectin-labelled cells than B. glabrata. Moreover, most of circulating hemocytes of B. tenagophila were intensively labelled by lectins PNA-FITC and WGA-FITC, while in B. glabrata small hemocytes were labeled mainly by ConA. Upon S. mansoni infection, lectin-labelled hemocytes almost disappeared from the hemolymph of Taim and accumulated in B. glabrata BH. The role of lectins/carbohydrate binding in resistance of B. tengophila infection to S. mansoni is still not fully understood, but the data suggest that there may be a correlation to its presence with susceptibility or resistance to the parasite.

Susceptibility of Biomphalaria amazonica and Biomphalaria occidentalis from Manso Dam, Mato Grosso, Brazil to infection with three strains of Schistosoma mansoni

As well as malaria and yellow fever, schistosomiasis is one of the main endemic diseases associated to environments which suffered some impact related to the development of great economic projects, as for example the construction of hydroelectric power stations. Aiming to investigate the occurrence and distribution of freshwater snails of medical and veterinary importance in the area which suffered impact from the Manso hydroelectric power station a survey was performed during the period of 2002 to 2003 and revealed the occurrence of populations of Biomphalaria amazonica and Biomphalaria occidentalis. Studies on parasite-mollusc compatibility were undertaken using five B. amazonica colonies (Barão de Melgaço, Poconé, Santo Antônio do Leverger, and Chapada dos Guimarães, in the Manso and Casca rivers), and four B. occidentalis colonies (Cuiabá, Santo Antônio do Leverger, and Chapada dos Guimarães, in the Agua Fria district and Casca river) were exposed to miracidia of Schistosoma mansoni. Of 257 snails of B. amazonica used, 17 became infected (infection index of 6.61 percent) and all specimens of B. occidentalis proved unsusceptible. According to the strains used, of the 158 snails exposed to BH miracidia, 6 became infected (3.79 percent); of the 44 exposed to SJ miracidia, 6 became infected (13.63 percent); and of the 55 snails of B. amazonica exposed to EC miracidia, 5 became infected (9.09 percent). These results point out the low possibility of introduction of schistosomiasis in those areas, but we believe it can not be discarded as due the presence of B. amazonica.

Distribuição geográfica das espécies dos caramujos transmissores de Schistosoma mansoni no Estado de São Paulo / Geographic distribution of Schistosoma mansoni transmitter snail species in State of São Paulo

Os conhecimentos sobre a distribuição geográfica das espécies dos caramujos transmissores de Schistosoma mansoni são importantes para o controle e vigilância epidemiológica da esquistossomose mansônica. O estudo da situação no Estado de São Paulo, Brasil, demandou o exame dos caramujos de 8.771 lotes com amostras do gênero Biomphalaria, preservados em coleção de moluscos da Superintendência de Controle de Endemias. Os exames revelaram espécies dos caramujos transmissores da endemia em 3.712 lotes com 108.244 exemplares. As proporções foram de 225 (6 por cento) lotes de Biomphalaria glabrata (Say, 1818), 3.402 (91,7 por cento) de Biomphalaria tenagophila (d'Orbigny, 1835) e 85 (2,3 por cento) de Biomphalaria straminea (Dunker, 1848), cada espécie respectivamente com 8.002 (7,4 por cento), 88.068 (81,4 por cento) e 12.174 (11,2 por cento) exemplares. A distribuição geográfica de B. glabrata e B. tenagophila apresenta criadouros muito agregados. No caso de B. tenagophila, a maior compactação de criadouros coincide em regiões com elevados níveis de urbanização, muito conurbadas e poluídas. Já B. straminea, encontrada em criadouros das áreas de drenagem de todas as bacias hidrográficas, mostra uma disseminação mais rarefeita. Presume-se que devido às maiores facilidades do contato parasita/hospedeiros, os agregados de criadouros de B. glabrata e B. tenagophila sejam propícios à preservação das áreas endêmicas de S. mansoni em São Paulo.