Biomphalaria Occidentalis Research Articles

Diversity of Freshwater Mollusks from Lake Pampulha, Municipality of Belo Horizonte, Minas Gerais, Brazil

The artificially created Lake Pampulha, within the metropolitan area of Belo Horizonte, Minas Gerais State, lacks detailed information about its freshwater mollusks, representing a challenge for the assessment and conservation of this ecosystem. In this study, conducted during June and August 2021, we collected specimens on four different occasions and at five sampling points around the lake, using different sampling equipment, such as a shovel and a scoop. During these collections, we identified, enumerated and measured 1538 species of mollusks and additionally examined the presence of trematode larvae. We identified twelve species of fresh water bivalves and gastropods: Biomphalaria straminea, Biomphalaria kuhniana, Biomphalaria occidentalis, Drepanotrema cimex, Pomacea maculata, Stenophysa marmorata, Physa acuta, Gundlachia ticaga, Melanoides tuberculata, Pseudosuccinea columella, Omalonyx matheroni and Corbicula largillierti. Echinostome and strigeocercaria types of larval trematodes were detected in B. straminea. Notably, some species of mollusks have not previously been recorded at Lake Pampulha. The analyses revealed differences in the composition and abundance of species, highlighting the higher number of mollusk species in areas more impacted by human actions. This study expands our understanding of mollusk diversity at Lake Pampulha, and provides valuable data for longitudinal comparisons of water quality and considerations of the conservation of native species. Furthermore, it highlights the importance of choosing appropriate sampling equipment, depending on the research objectives. The presence of invasive species of medical and veterinary relevance as intermediate hosts of parasites reinforces the need for efficient environmental protection strategies to preserve this artificial, aquatic environment widely used by the local population and by tourists.

Modelling the present and future distribution of Biomphalaria species along the watershed of the Middle Paranapanema region, São Paulo, Brazil

The Middle Paranapanema region in the state of São Paulo, Brazil, is an area with high diversity for Biomphalaria species, with municipalities historically marked by cases of schistosomiasis transmission. The objectives of the study were to evaluate the current distribuition and predict the future distribution of habitats of Biomphalaria species at a high spatial resolution along 114 freshwater sites in the Middle Paranapanema watershed. The modelling encompassed 55 municipalities of the Middle Paranapanema region, which were analyzed through the maximum entropy algorithm. All geographic coordinates of the Biomphalaria species collected from 2015-2018 and environmental data were obtained through WorldClim, HydroSHEDS, TOPODATA and Secretaria do Meio Ambiente for the 1970-2017 period. For the 2041-2060 period we used the HadGEM2-ES climate model. Due to climate change, MaxEnt showed that there was a high probability for the maintenance of B. glabrata habitats near Ourinhos and Assis, an expansion of scattered spots, and a 50% probability that the species will spread throughout new suitable areas. The results showed that the geographical range of B. straminea will most likely expand in the future along the Middle Paranapanema hydrographic basin, especially in the municipalities near Ourinhos. For B. glabrata and B. straminea, the geographic expansion was related to the predicted increase in the annual temperature range. The habitats suitable for B. tenagophila and B. peregrina seemed to slightly expand around the west border of the Middle Paranapanema region. Biomphalaria occidentalis may have a small reduction in its distribution due to climate change. The variables that contributed the most to the future modelling for these three species were precipitation and temperature. Identifying the sites with intermediate hosts for schistosomiasis may guide public health measures to avoid or reduce future transmissions in this region.

Molecular evidence of new freshwater turtle blood flukes (Digenea: Spirorchiidae) in the intermediate snail host Biomphalaria occidentalis Paraense, 1981 in an urban aquatic ecosystem in Brazil.

In this study, two potentially new species of turtle blood flukes (TBFs) (Digenea: Spirorchiidae) have been recorded from South Brazil. The spirorchiid parasites infect the vascular system of turtles, thereby compromising their health. The life cycle of these parasites is not well studied. The larval stage of cercaria is found in intermediate gastropod hosts, with some species presenting similar morphological characteristics, which can result in misinterpretations when using only morphological taxonomy for species identification. In this study, we recorded a single morphotype belonging to the family Spirorchiidae in Biomphalaria occidentalis in an urban aquatic ecosystem in Brazil. However, molecular data (28S rDNA and cytochrome oxidase subunit I) confirmed the presence of two species of Spirorchiidae in the sampled environment; both phylogenetically close to genera previously studied in freshwater turtles from the Peruvian Amazon. In this study, species characterization was possible because of molecular tools. We recommend using more than one molecular marker in future studies focusing on TBFs, which need attention about their evolutionary history and ecology to understand their distribution in South America.

Taxonomic diversity of Biomphalaria (Planorbidae) in São Paulo state, Brazil

Abstract: Morphological and molecular identifications were carried out for Biomphalaria occidentalis, Biomphalaria oligoza, Biomphalaria peregrina, Biomphalaria schrammi, Biomphalaria straminea and Biomphalaria tenagophila collected from 55 sites located along the upper basin of Tietê River in the Southeast Region of Brazil. Morphological analysis considered aspects of the shell, mantle, excretory organs and reproductive system. Molecular data included 122 sequences of Cytochrome C Oxidase I gene (COI). Our results showed that some shell characters, as well as other characters related to the mantle and the reproductive system, are fundamental for the identification of the six Biomphalaria species included in this study. The use of DNA barcoding together with morphological taxonomy generated more reliable results, proving to be a very useful approach, even for malacological surveillance services.

Mollusks of the genus Biomphalaria Preston, 1910 in Amazon Region: first report of Biomphalaria occidentalis Paraense, 1981 in Pará State, Brazil

INTRODUCTION: In Para State, Northern Region of Brazil, there are reports of the occurrence of Biomphalaria glabrata, Biomphalaria straminea, Biomphalaria schrammi, and Biomphalaria kuhniana. OBJECTIVE: To report the first existence of Biomphalaria occidentalis in Para State. MATERIALS AND METHODS: Five mollusks were collected, examined for the presence of Schistosoma mansoni cercariae, and morphological and molecular taxonomies were performed. RESULTS: No specimens parasitized by trematode larvae were detected. Biomphalaria occidentalis was identified, being the first record in Para State. CONCLUSION: The result obtained contributed to improve the knowledge about the dispersion and diversity of the Biomphalariamollusks in Amazon Region.

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

Abstract: 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 Sao 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.

Morphological and ITS2 Molecular Characterization of Ribeiroia Cercariae (Digenea: Psilostomidae) from Biomphalaria spp. (Gastropoda: Planorbidae) in Northern Argentina.

Species of Ribeiroia use planorbid snails as intermediate host. Since there is little information about these digenean parasites in South America, we aimed to assess whether Ribeiroia cercariae from 3 north Argentina locations belonged to the same species and differed from Ribeiroia cercariae described elsewhere. Specimens were obtained from Biomphalaria tenagophila and Biomphalaria orbignyi (Salta Province), and Biomphalaria occidentalis (Corrientes Province). Morphological traits of cercariae were analyzed, as well as their sequence of the ribosomal internal transcribed spacer 2 (ITS2). The ITS2 region consisted of 426 nucleotides identical in all samples, suggesting that all specimens belong to the same species in spite of their morphological differences and first intermediate host species. Comparison of the ITS2 region with GenBank database records showed that specimens from Argentina were different from Ribeiroia ondatrae (0.9% divergence), Ribeiroia marini (0.7% divergence), and Cercaria lileta (0.2% divergence). In summary, morphological, ecological, and ITS2 molecular data suggest that specimens from Argentina belong to a different species.

Larval trematodes in freshwater gastropods from Mato Grosso, Brazil: diversity and host-parasites relationships

A survey for freshwater gastropods carrying trematodes parasites was conducted in Manso Dam and the surrounding areas frequented by tourist, focusing particularly on the Pantanal region. Infected snails were recovered from twelve of the eighteen investigated municipalities and forty-one cercaria-snail pairings were recorded. Among these pairings were several first records of snails serving as intermediate hosts for trematodes in Brazil including Biomphalaria amazônica Paraense, 1966, Biomphalaria occidentalis Paraense, 1981, Marisa planogyra Pilsbry, 1933, Pomacea maculata Perry, 1830, Pomacea scalaris (d'Orbigny, 1835) and Gundlachia radiata (Guilding, 1828). Echinostomatidae and Strigeidae were the most common trematode families (ca. 47%) and the greatest diversity of larvae were obtained from Drepanotrema lucidum (Pfeiffer, 1839). Paramphistomatidae, Schistosomatidae or Spirorchiidae and Notocotylidae or Pronocephalidae were recovered in D. lucidum for the first time extending the number of families which use this gastropod as intermediate host. Although no specimens were found harboring larval stages of Schistosoma mansoni Sambon, 1907 other trematode larvae were discovered, including the Schistosomatidae Brevifurcate apharingeate cercaria that can cause dermatitis in humans. Continued studies on the taxonomy and biology of trematodes are essential to better understand the biodiversity of these parasites as well as the epidemiological aspects for control of associated zoonosis.

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%) 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%); of the 44 exposed to SJ miracidia, 6 became infected (13.63%); and of the 55 snails of B. amazonica exposed to EC miracidia, 5 became infected (9.09%). 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.

Resistance of Biomphalaria occidentalis from Varzea das Flores dam, Minas Gerais, to Schistosoma mansoni infection detected by low stringency polymerase chain reaction.

Biomphalaria occidentalis Paraense, 1981 from Varzea das Flores dam, MG, Brazil, was exposed to infection with Schistosoma mansoni. Individual infection was performed with 140 B. occidentalis and 100 B. glabrata snails using LE and SJ strains. Two groups of B. occidentalis were killed after seven day-miracidia exposure to detect S. mansoni DNA, through the low stringency polymerase chain reaction (LS-PCR), and were negative. The infection rates were 69.2% (LE strain) and 96.7% (SJ strain) for B. glabrata and 0% for B. occidentalis. LS-PCR enabled early resistance diagnosis.

History of the discovery of Biomphalaria occidentalis Paraense, 1981

The article addresses the discovery of Biomphalaria occidentalis Paraense, a mollusk whose shell is indistinguishable from that of B. tenagophila, natural vector of Schistosoma mansoni. This reconstruction of the history of its discovery necessarily entails reference to the professional life of malacologist Wladimir Lobato Paraense. In addition to demonstrating how essential basic biology and taxonomy are in the epidemiology of mansoni schistosomiasis, the study also focuses on the discovery process itself and the socioeconomic factors which influenced it.

Specific Identification of Biomphalaria tenagophila and Biomphalaria occidentalis Populations by the Low Stringency Polymerase Chain Reaction

Although Biomphalaria occidentalis and B. tenagophila are indistinguishable on the basis of shell morphology and the majority of their genital organs, only the latter is susceptible to infection with Schistosoma mansoni. Thus, the identification of these species is fundamental to epidemiological studies of schistosomiasis. Here we describe a simple and rapid method for differentiating B. tenagophila from B. occidentalis based on low stringency polymerase chain reaction and using a pair of primers specific for the amplification of the 18S rRNA gene. Analysis of the low stringency product profiles of populations of these snails from different geographical regions confirmed this approach as being applicable to the identification of B. tenagophila and B. occidentalis in cases where classical morphology is inconclusive

Biomphalaria occidentalis Paraense, 1981 in the State of Minas Gerais, Brazil.

A population of Biomphalaria occidentalis was found for the first time in the State of Minas Gerais. It was probably introduced into the Várzea das Flores dam, in the municipality of Contagem, the area of study, during fish stocking in 1985. There is the possibility of "competitive exclusion" between that species and B. glabrata, previously the only Biomphalaria found in the region. The present geographical distribution of B. occidentalis in Brazil is listed.

Spatial and seasonal trends of a natural population of Biomphalaria occidentalis in northeastern Argentina.

This study aims to analyze the age structure of a population of Biomphalaria occidentalis on a pond of Riachuelo river basin, which is one of the three most important Middle Paraná river affluents in Corrientes province. Samples were drawn from three stations, where spatial and temporal numerical variations of the snail, as well as its relation with different environmental parameters, mainly temperature, rainfall, pH and conductivity, were analyzed. Snail abundance is given in number of individuals/hour. The differences between the three sampling stations, estimated by nonparametric tests, was nonsignificant. A relative scale to the greatest shell diameter was employed to build the age pyramids. Temporal fluctuations of snail abundance correlated negatively with the highest monthly accumulated temperatures (P < 0.05). Although different floristic compositions were observed at the three stations, no significant numerical variations were detected in B. occidentalis spatial distribution. Reproductive activity took place between March-April and November with overlapping cohort system. During summer (December-February) mortality increased along with temperature and reproductive activity was not evident.

Differentiation of the sibling species Biomphalaria occidentalis and Biomphalaria tenagophila by the electrophoretic patterns of their hemoglobin.

A simple and rapid method for differentiating the sibling species Biomphalaria tenagophila and Biomphalaria occidentalis by agarose gel electrophoresis (AGE) is described. Snail hemolymph is used as the test sample and the red coloration of the hemoglobin fraction permits visualization of the migration patterns without resorting to specific stains. Moreover, hemolymph samples may be obtained without killing the snail, thus permitting its use for other studies or for breeding.

Biomphalaria Tenagophila Guaibensis ssp. n. from Southern Brazil and Uruguay (pulmonata: Planorbidae). I. Morphology

A new subspecies of planorbid snail, biomphalaria tenagophila guaibensis, is described. It has been found along the coastal belt of the Brazilian state of rio grande do Sul and the middle part of Uruguay, from Porto Alegre to Mercedes. It differs from the nominate subspecies, Biomphalaria tenagophila tenagophila, in the appearance of the penial complex (prepuce longer and proportionally slenderer in B. t. guaibensis, shorter and proportionally stouter in b. t. tenagophila), in the ratio between the lengths of the penial sheath and the prepuce, in the ratio between the lengths of the uterine complex and the penial complex, and in a coefficient of difference of 2.44 for the ratio between the penis sheath and prepuce and of 2.02 for the ratio between the uterine complex and penial complex. The shell and the other organs of the genital system are similar in both subspecies. B. t. guaibensis is very similar to Biomphalaria occidentalis Paraense, 1981, but is readily separated from it by the presence of a vaginal pouch, which is lacking in the latter, besides showing highly significant difference in the penis sheath: prepuce and uterine complex: penial complex ratios. Crossbreeding experiments which lend additional support to the recognition of B. t. guaibensis as a subspecies will be reported elsewhere.

Suscetibilidade de Biomphalaria occidentalis do Acre e Mato Grosso à infecção pelo Schistosoma mansoni e sua implicação na epidemiologia da esquistosomose na Amazônia Ocidental, Brasil ()

Resumo É testada a suscetibilidade da Biomphalaria occidentalis de Sena Madureira (Acre) e Cuiabá (Mato Grosso) à infecção pelas cepas de Schistosoma mansoni de São José dos Campos (São Paulo) e Paulista (Pernambuco), com resultado negativo. São tecidas considerações sobre os focos de esquistossomose descritos na região Amazônica e discute-se o potencial de transmissão de S. mansoni por B. occidentalis na Amazónia Ocidental.

Unsusceptibility of Biomphalaria occidentalis to infection with a strain of Schistosoma mansoni.

Susceptibility experiments with 1582 specimens of Biomphalaria occidentalis, 3-6 mm in shell diameter, from 10 localities of the states of Mato Groso, Mato Grosso do Sul, Paraná and São Paulo, exposed individually to 5 miracidia of Schistosoma mansoni (SJ2 strain), gave negative results. B. tenagophila from Joinville (Santa Catarina) and Taubaté (São Paulo), used as controls, showed infection rates of 17.9% and 14.8%, respectively. Experiments with other strains of S. mansoni are in progress. If the present results are confirmed, expansion of schistosomiasis toward far-western Brazil through the agency of B. occidentalis becomes less probable.

Biomphalaria occidentalis sp.n. from South America (Mollusca basommatophora pulmonata)

A new species of South American planorbid snail, Biomphalaria occidentalis, is described. It is indistinguishable from B. tenagophila (Orbigny, 1835), by the characteristics of the shell and of most organs of the genital system. In B. tenagophila there is a pouch on the ventral wall of the vagina (Fig. 4A, vp), absent in B. occidentalis (Fig. 3A), and on the ventral wall of the vagina (Fig. 4A, vp), absent in B. occidentalis (Fig. 3A), and the prepuce is much wider than the penial sheath, its width increasing distalward (Fig. 4, ps,pp), whereas in B. occidentalis the prepuce is wider than the penial sheath but keeps about the same width all along (Fig.3, ps, pp). The two species are biologically separate by absolute reproductive isolation. The geographical distribution of B. occidentalis is shown in Fig. 14. So far it has been found in the Brazilian states of Acre, Amazonas (?), Mato Grosso, Mato Grosso do Sul and Paraná, and in Paraguay. Its type-locality is Campo Grande, state of Mato Grosso do sul, where it was collected from several biotopes related to affluents of the Aquiduana river, chiefly Córrego Prosa and Córrego Ceroula. Specimens were deposited in the following malacological collections: Instituto Oswaldo Cruz, Rio de Janeiro; Academy of Natural Sciences, Philadelphia; Museum of Zoology, University of Michigan; and British Museum (Natural History).