Experimental infection with Schistosoma mansoni from Belém, Pará, Brazil: Strains newly isolated vs. laboratory maintained.

BACKGROUND: Schistosomiasis is a neglected tropical disease that occurs in locations with inadequate sanitation conditions. The geographic distribution of Schistosoma mansoni trematode depends directly on the presence of its intermediate host, Biomphalaria mollusks. Studies involving recently isolated and laboratory strains are not common due to the difficulty in cycle maintenance. This study evaluated the susceptibility and infectivity responses in intermediate and definitive hosts with strains of S. mansoni, one isolated and kept in laboratory environment for 34 years (BE) and the other recently collected (BE-I) METHODS: For experimental infection, a total of 400 B. glabrata mollusks were divided in four infection groups. Thirty mice were divided in two groups for infection with the two strains. RESULTS: It was possible to notice differences about S. mansoni infection in both strains. The laboratory strain was more harmful to freshly collected mollusks. Differences in the patterns of infection in mice could be observed. CONCLUSION: Particularities occurred in each group of infection by S. mansoni strains, despite having the same geographic origin. Effects from the parasite-host interaction are visible in terms of infection in definitive and intermediate hosts.

First report of Biomphalaria tenagophila (d'Orbigny, 1835) (Gastropoda/Planorbidae) in Pará State, Amazon region of Brazil.

INTRODUCTION: Mollusks belonging to Biomphalaria genus are intermediate hosts of Schistosoma mansoni. In the Pará State, Northern Region of Brazil, there are reports of B. glabrata, B. straminea, B. schrammi, B. occidentalis, and B. kuhniana occurrence. Here, we report for the first time the presence of B. tenagophila in Belém, capital of Pará state. METHODS: A total of 79 mollusks were collected and examined to search for possible S. mansoni infection. The specific identification was made by morphological and molecular assays. RESULTS: No specimens parasitized by trematode larvae were detected. For the first time the presence of B. tenagophila in Belém, capital of Pará state, was reported. CONCLUSION: The result increases the knowledge about Biomphalaria mollusks occurrence in the Amazon Region and specifically alerts on the possible role of B. tenagophila in schistosomiasis transmission in Belém.

A preliminary study on the distribution of breeding sites of BIOMPHALARIA GLABRATA in the municipality of peri mirim, a low endemicity area for schistosomiasis in northeast Brazil

Information on areas colonized by snails that transmit Schistosoma mansoni is essential for planning schistosomiasis control measures. Therefore, the purpose of this study was to map the natural breeding sites of Biomphalaria spp. in the municipality of Peri Mirim, Maranhão, Brazil. The snails were manually collected and the breeding sites were geo-referenced (seven in the urban area and five in flooded fields), from November 2017 to March 2018. In the laboratory, the snails were examined for the presence of larval stages of S. mansoni identified by morphology and internal anatomy analysis. While no snails were found in the urban area, sixteen B. glabrata were collected in the flooded fields. No S. mansoni or other trematode infections were detected. Wild rodents, most likely Holochilus sciureus that could act as S. mansoni reservoirs, were also found in the flooded fields. These data indicate possible risk areas for further outbreaks of schistosomiasis transmission in the municipality of Peri Mirim.

Freshwater mollusks from three reservoirs of Piauí, northeastern Brazil / Moluscos límnicos de três reservatórios do Piauí, nordeste do Brasil

Abstract: The pronounced dry season determines the characteristics of the semiarid region of Brazil. Numerous small reservoirs are built to overcome this condition, accumulating multiple uses and causing important changes in the landscape and the local biota. Considering the limited amount of information about the malacofauna of reservoirs, mainly in the Northeast region of the country, this inventory provides a list of mollusks from three important reservoirs located in the city of São Julião, state of Piauí. The collections were carried out monthly between May/2017 and April/2018, sampling a total of 11,149 mollusks, corresponding to the species Melanoides tuberculata (Müller, 1774) (n = 9,724), Biomphalaria straminea (Dunker, 1848) (n = 1,361) and Pomacea lineata (Spix, 1827) (n = 64). The richness of mollusks from the three reservoirs was low, similar to those described in studies conducted in other regions of Northeast Brazil. There was a significant difference in the abundance of M. tuberculata and B. straminea among the studied reservoirs. These environments are not connected and are installed in urban and rural areas, presenting different ecological conditions. The relationship between the human population and the reservoirs, associated with the lack of sanitation, increases the risks of spreading waterborne diseases besides the development of environmental imbalance by the introduction of exotic species.

Resumo: O período de seca pronunciado marca a região semiárida brasileira. Para superação dessa condição inúmeros reservatórios de pequeno porte são construídos, acumulando múltiplos usos e causando alterações importantes na paisagem e na biota local. Considerando as poucas informações sobre a malacofauna de reservatórios, principalmente na região nordeste do país, este trabalho apresenta o inventário das espécies de moluscos provenientes de três importantes reservatórios localizados no município de São Julião, estado do Piauí. As coletas foram realizadas mensalmente entre os meses de maio/2017 e abril/2018. Foi amostrado um total de 11.149 moluscos, correspondentes as espécies Melanoides tuberculata (Müller, 1774) (n=9,724), Biomphalaria straminea (Dunker, 1848) (n=1,361) e Pomacea lineata (Spix, 1827) (n=64). A riqueza de moluscos amostrados nos três reservatórios foi baixa, não diferindo daquelas descritas em estudos realizados em outras regiões do Nordeste do Brasil. Houve diferença significativa na abundância de M. tuberculata e B. straminea entre os reservatórios estudados os quais não são conectados e encontram-se instalados em áreas urbana e rurais, com condições ambientais distintas. A relação entre a população humana da região e os reservatórios, juntamente com a falta de saneamento representam riscos à propagação de doenças transmitidas pela água e desequilíbrio ambiental pela introdução de espécies exóticas.

Radula and mandible of Biomphalaria (Planorbidae) of São Paulo, Brazil

The radular apparatus of Biomphalaria occidentalis Paraense, 1981, Biomphalaria oligoza Paraense, 1971, Biomphalaria peregrina (d’Orbigny, 1835), Biomphalaria schrammi (Crosse, 1864) and Biomphalaria tenagophila (d’Orbigny, 1835) from the Metropolitan Region of São Paulo, Brazil were analyzed from Scanning Electron Microscope (SEM) micrographs. The data support the usage of characters of central, lateral and intermediate teeth in the species identification of Biomphalaria. The use of SEM provided additional quantitative and structural details to radula descriptions, which are extremely important for elucidating the taxonomy of Biomphalaria species...

Putative new genera and species of avian schistosomes potentially involved in human cercarial dermatitis in the Americas, Europe and Africa.

New larval avian schistosomes found in planorbid snails from Brazil and USA were used for morphological and molecular studies. Eggs with a distinctive long polar filament were found in ducks infected experimentally with Brazilian cercariae. Similar eggs were reported previously in wild or experimentally infected anatids from Brazil, South Africa, and the Czech Republic. Molecular phylogenetic analyses showed that the North American and European schistosomes are sister taxa, which are both sister to the Brazilian species. However, these clades do not group with any named genus. Molecular data plus egg morphology suggest that these are new putative genera and species of avian schistosomes that can cause human cercarial dermatitis in the Americas, Africa and Europe.

The South-American distribution and southernmost record of Biomphalaria peregrina-a potential intermediate host of schistosomiasis.

Schistosomiasis remains a major parasitic disease, endemic in large parts of South America. Five neotropical species of Biomphalaria have been found to act as intermediate hosts of Schistosoma mansoni in natural populations, while others have been shown to be susceptible in experimental infections, although not found infected in the field. Among these potential intermediate hosts, Biomphalaria peregrina represents the most widespread species in South America, with confirmed occurrence records from Venezuela to northern Patagonia. In this study, we report the southernmost record for the species at the Pinturas River, in southern Patagonia, which finding implies a southward reassessment of the limit for the known species of this genus. The identities of the individuals from this population were confirmed through morphological examination, and by means of two mitochondrial genes, cytochrome oxidase subunit I (COI) and 16S-rRNA. With both markers, phylogenetic analyses were conducted in order to compare the genetic background of individuals from the Pinturas River with previously genetically characterized strains of B. peregrina from various South-American locations. In addition, we produced a potential distribution model of B. peregrina in South America and identified the environmental variables that best predict that distribution. The model was estimated through a maximum entropy algorithm and run with occurrence points obtained from several sources, including the scientific literature and international databases, along with climatic and hydrographic variables. Different phylogenetic analyses with either the COI or 16S-rRNA sequences did not conflict, but rather gave very similar topological organizations. Two major groups were identified, with sequences from the Pinturas River grouping together with haplotypes from subtropical and temperate regions. The model developed had a satisfactory performance for the study area. We observed that the areas with higher habitat suitability were found to be mainly linked to subtropical and temperate regions of South America between 15° and 45° south latitude, with different moderate- and low-suitability areas outside this range. We also identified the coldest temperatures as the main predictors of the potential distribution of this snail. Susceptibility surveys would be required to evaluate if southern populations of B. peregrina still retain their potential as intermediate hosts of S. mansoni.

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.

Growth rate fitting using the von Bertalanffy model: analysis of natural populations of Drepanotrema spp. snails (Gastropoda: Planorbidae)

The genus Drepanotrema includes six species in Argentina. The life cycle in natural systems of Drepanotrema depressissimum, and D. lucidum has been little studied, except for some casual observations. The aim of this study is to analyze main population trends (age structures, recruitment periods, life span and curves of individual growth) in Paiva pond, Argentina. We explored growth model fitting and comparison methodologies between species and environments in Paiva pond and Isla Martín García (IMG), to determine interspecific patterns. Theoretical curves of von Bertalanffy’s model for each population were contrasted with samplings using the χ2 test. Expected sizes were transformed into a percentage of maximum size and cohorts started from zero time, which allowed them to be independent of the real or estimated starting date and a comparison was possible. A similar time scale was used, because the k values proved to be sensitive to time scale. Maximum size reached by D. lucidum was 6.9 mm and by D. depressissimum 9.38 mm. Growth rates (k) fluctuated from 1.302 to 1.368 in the first and 1.339 to 1.509 in the second species. No statistically significant differences were found in growth curves among species inhabiting the Paiva pond and in the different IMG water bodies independent of the beginning of each cohort and maximum size. In general, no winter cohorts were observed, except in one population of D. kermatoides (IMG). Comparing circannual and biannual growth rhythms most of the species reached 60 % of their development during their first year, and 85 % or more during their second year. Rev. Biol. Trop. 55 (2): 559-567. Epub 2007 June, 29.

En Argentina se encuentran seis especies del género Drepanotrema. El ciclo de vida en sistemas naturales de Drepanotrema depressissimu y D. lucidum ha sido muy poco estudiado, excepto por algunas observaciones aisladas. El objetivo de este estudio es analizar las principales tendencias de la población en la Laguna Paiva, Argentina. Usamos modelos de crecimiento y metodologías comparativas entre las especies y los ambientes en Paiva y la isla Martín García (IMG). Además, las curvas teóricas del modelo de von Bertalanffy para cada población fueron contrastadas con las muestras utilizando la prueba χ². Los tamaños esperados fueron transformados en porcentajes de tamaño máximo y las cohortes se iniciaron a partir del tiempo cero, lo cual les permitió ser independientes de la fecha inicial real o estimada y con ello ser comparables. Se utilizó una escala de tiempo similar debido a que los valores de k demostraron ser sensibles a la escala de tiempo. El tamaño máximo alcanzado por D. lucidum fue de 6.9 mm y por D. depressissimun fue de 9.38 mm. Las tasas de crecimiento (k) fluctuaron de 1.302-1.368 en la primera especie y 1.339-1.509 para la segunda especie. No fueron encontradas diferencias significativas en las curvas de crecimiento entre las especies que habitaban en Paiva ni en los diferentes cuerpos de agua de IMG, independientes del inicio de cada cohorte y del tamaño máximo. En general no se observaron cohortes de invierno, excepto en una población de D. kermatoides (IMG). Al comparar los ritmos de crecimiento anuales y semestrales, la mayoría de las especies alcanzaron el 60 % de su desarrollo durante el primer año y el 85 % ó más durante su segundo año.

Influence of saccharose on the development of cercariae from Schistosoma mansoni strains BH and SJ

The development of cercariae from Schistosoma mansoni strains BH and SJ in Biomphalaria glabrata and Biomphalaria tenagophila treated with saccharose was studied. The molluscs were maintained in dechlorinated tap water containing 0.01% saccharose. After one week of treatment with saccharose, B. glabrata and B. tenagophila were exposed to ten S. mansoni miracidia, from BH and SJ strains respectively. Control snails of both species were maintained in dechlorinated tap water without saccharose and exposed to the same number of miracidia. There was no significant difference between the infection rates of snails treated or not with saccharose. However, the two groups of B. glabrata had significantly greater infection rates than the corresponding B. tenagophila groups. Molluscs treated with saccharose had a lower survival rate, with the greatest mortality occurring immediately before and at the beginning of cercariae release. Treatment with saccharose did not result in the release of more cercariae, but larvae from molluscs so treated showed a greater capacity to penetrate mouse skin, which was attributed to the greater energy supply during larval development in the mollusc.

Foi estudado o desenvolvimento de cercárias de Schistosoma mansoni das linhagens BH e SJ em Biomphalaria glabrata e Biomphalaria tenagophila, respectivamente, tratadas com sacarose. Os moluscos foram mantidos em água declorada contendo 0,01% de sacarose. Após uma semana de tratamento com sacarose, B. glabrata e B. tenagophila foram expostas a dez miracídios de S. mansoni das linhagens BH e SJ, respectivamente. Moluscos controles de ambas as espécies mantidos em água declorada sem sacarose foram expostos ao mesmo número de miracídios. Não houve diferença significativa entre as taxas de infecção dos moluscos tratados ou não com sacarose. Entretanto, os dois grupos de B. glabrata tiveram taxas de infecção significativamente maiores que as correspondentes aos grupos de B. tenagophila. Moluscos tratados com sacarose apresentaram menor taxa de sobrevivência, com a maior mortalidade ocorrendo imediatamente depois e no início da liberação de cercárias. O tratamento com sacarose não resultou na maior liberação de cercárias, mas larvas de moluscos tratados com esse açúcar mostraram maior capacidade de penetrar na pele de camundongo, o que foi atribuído ao maior suprimento de energia durante o desenvolvimento larval no molusco.

The genus Plesiophysa, with a redescription of P. ornata (Haas, 1938) (Gastropoda: Planorbidae)

A redescription of conchological and anatomical characters of the planorbid mollusc Plesiophysa ornata (Haas, 1938) is presented, based on topotypic material and specimens from 14 additional localities in the Brazilian states of Rio Grande do Norte, Paraíba, Sergipe, Bahia, Espírito Santo and Minas Gerais. Due to the close similarity of their shells, a sure discrimination of the five species of Plesiophysa described so far (P. pilsbryi, P. granulata, P. guadeloupensis, P. ornata and P. hubendicki) is only possible through their anatomical features. The present study points to the high probability of synonymy of P. hubendicki with P. ornata. Investigations on the anatomy of P. pilsbryi and P. guadeloupensis are needed to define their taxonomic relation with the other nominal species.

É apresentada uma descrição de caracteres conquiliológicos e anatômicos do molusco planorbídeo Plesiophysa ornata (Haas, 1938), baseada em material topotípico, de 14 outras localidades dos seguintes Estados brasileiros: Rio Grande do Norte, Paraíba, Sergipe, Bahia, Espírito Santo e Minas Gerais. Devido à grande semelhança de suas conchas, uma distinção segura das cinco espécies de Plesiophysa até agora descritas (P. pilsbryi, P. granulata, P. guadeloupensis, P. ornata e P. hubendicki) só é possível por intermédio de suas características anatômicas. Os dados sobre B. hubendicki indicam alta probabilidade de sinonímia com P. ornata. São necessárias investigações sobre a anatomia de P. pilsbryi e P. guadeloupensis para definir sua relação taxionômica com as outras espécies nominais.

The genus Plesiophysa, with a redescription of P. ornata (Haas, 1938) (Gastropoda: Planorbidae)

A redescription of conchological and anatomical characters of the planorbid mollusc Plesiophysa ornata (Haas, 1938) is presented, based on topotypic material and specimens from 14 additional localities in the Brazilian states of Rio Grande do Norte, Paraíba, Sergipe, Bahia, Espírito Santo and Minas Gerais. Due to the close similarity of their shells, a sure discrimination of the five species of Plesiophysa described so far (P. pilsbryi, P. granulata, P. guadeloupensis, P. ornata and P. hubendicki) is only possible through their anatomical features. The present study points to the high probability of synonymy of P. hubendicki with P. ornata. Investigations on the anatomy of P. pilsbryi and P. guadeloupensis are needed to define their taxonomic relation with the other nominal species.

É apresentada uma descrição de caracteres conquiliológicos e anatômicos do molusco planorbídeo Plesiophysa ornata (Haas, 1938), baseada em material topotípico, de 14 outras localidades dos seguintes Estados brasileiros: Rio Grande do Norte, Paraíba, Sergipe, Bahia, Espírito Santo e Minas Gerais. Devido à grande semelhança de suas conchas, uma distinção segura das cinco espécies de Plesiophysa até agora descritas (P. pilsbryi, P. granulata, P. guadeloupensis, P. ornata e P. hubendicki) só é possível por intermédio de suas características anatômicas. Os dados sobre B. hubendicki indicam alta probabilidade de sinonímia com P. ornata. São necessárias investigações sobre a anatomia de P. pilsbryi e P. guadeloupensis para definir sua relação taxionômica com as outras espécies nominais.