Showing papers on "Bulinus truncatus published in 2011"

Population dynamics of freshwater snails (Mollusca: Gastropoda) at Qena Governorate, Upper Egypt

Abstract: Monthly and seasonal fluctuations in densities of freshwater snails were recorded in six different sites at Qena Governorate during the period of March 2009 February 2010. The study revealed the occurrence of 13 species of freshwater snails belonging to 9 families of class Gastropoda. The snail species and their total catch were: Cleopatra bulimoides (1704 specimens), Lanistes carinatus (1468 specimens), Melanoides tuberculata (1036 specimens), Gabbiella senaariensis (731 specimens) Theodoxus niloticus (670 specimens), Bellamya unicolor (588 specimens), Physa acuta (213 specimens), Lymnaea natalensis (145 specimens), Succinea cleopatra (85 specimens), Bulinus truncatus (73 specimens), Biomphalaria alexandrina (41 specimens), Gyraulus ehrenbergi (12 specimens) and Helisoma duryi (2 specimens) in a descending order. The densities of the recorded snails varied seasonally and the general seasonal peak was recorded during Autumn while the lowest density observed during Winter. Ecological factors which may influence the distribution of the recorded snails were also determined (water temperature, pH, dissolved oxygen conductivity, total hardness, total dissolved salts, water depth and percentage of macrophytes).

Molecular approaches to the identification of Bulinus species in south-west Nigeria and observations on natural snail infections with schistosomes.

Abstract: The current study considers the distribution of a small sample of 138 Bulinus snails, across 28 localities within eight Nigerian states. Snails were identified using a combination of molecular methods involving both DNA sequencing of a partial cytochrome oxidase subunit 1 (cox1) fragment and restriction profiles obtained from ribosomal internal transcribed spacer (its) amplicons. The results showed that the majority of Bulinus samples tested belonged to the species Bulinus truncatus while only two were Bulinus globosus. The use of RsaI restriction endonuclease to cleave the ribosomal its of Bulinus, as a method of species identification, was adopted for the majority of samples, this being a quicker and cheaper method better suited to small laboratory environments. Polymerase chain reaction (PCR) amplification of the schistosome Dra1 repeat within each of the collected Bulinus samples was employed to determine the extent and distribution of infected snails within the sample areas. Successful amplification of the Dra1 repeat demonstrated that 29.7% of snails were infected with schistosomes. Sequencing of the partial schistosome its from a small subset of snail samples suggested that some snails were either penetrated by both Schistosoma haematobium and Schistosoma bovis miracidia or hybrid miracidia formed from the two species.

A molecular phylogenetic analysis of Bulinus (Gastropoda: Planorbidae) with conserved nuclear genes

Abstract: Jorgensen, A., Madsen, H., Nalugwa, A., Nyakaana, S., Rollinson, D., Stothard, J. R. & Kristensen, T. K. A molecular phylogenetic analysis of Bulinus (Gastropoda: Planorbidae) with conserved nuclear genes. —Zoologica Scripta, 40, 126–136. Mutational saturation of inspected DNA loci and topological incongruence in the phylogenetic inferences have previously confounded attempts to resolve the evolutionary relationships within the freshwater snail genus Bulinus. Traditionally, the 37 species of Bulinus are placed within the four species groups and the evolutionary divergence between groups is substantial. With an intention to shed new light on species group relationships, the present study was designed to investigate the basal divergences in the phylogeny of Bulinus using highly conserved nuclear genes. The resolved phylogeny inferred that the four species groups of Bulinus were monophyletic and Shimodaira-Hasegawa topology tests found them to be significantly supported. The Bulinus truncatus/tropicus species complex and Bulinus wrighti (Bulinus reticulatus group) formed a well-supported sister-group relationship. The Bulinus africanus species group was the sister-group to the clade (Bulinus truncatus/tropicus + B. wrighti) with the Bulinus forskalii species group as the sister-group to these taxa. The sister-group relationship between Indoplanorbis and Bulinus was non-significant and the basal clade support of Bulinus improved upon exclusion of Indoplanorbis. The finding of basal long branches of Bulinus species originating from Madagascar strongly suggests the presence of additional cryptic species and an evolutionary scenario influenced by this island’s geological vicariance from the African mainland. Speciation by polyploidy was inferred to have evolved within a clade in the Bulinus truncatus/tropicus species complex. Although the monophyletic status of each species group was firmly supported, it was difficult to establish species group concepts equally across the variations and place this precisely in a specific temporal framework.

Can the freshwater crayfish eradicate schistosomiasis in Egypt and Africa

Abstract: Schistosomiasis is a chronic, parasitic disease, infecting more than 207 million people, mostly from Africa, with an estimated 700 million people at risk in 74 endemic countries. One of strategies to eradicate this disease is biocontrol of its vector snail. Lab experiments and field survey have been carried out to investigate the impact and the relationship between the exotic crayfish; Procambarus clarkii and Schistosoma vector snails in Egypt. In the Lab, several species of freshwater snails, fish and aquatic plants were reported to serve as food for the freshwater crayfish. In the field, a survey for the crayfish and freshwater snails has been conducted at several irrigation channels in Qalyobiya, Ismailia and Behera governorates, which had been previously surveyed during 1990s . The results of the experimental Lab indicated that the vector snails; Biomphalaria alexandrina, Bulinus truncatus and Limnaea natalensis were the preys of first choice for the crayfish. The fields surveys showed high reduction and sometimes complete disappearance of vector snails in irrigation channels, which have been invaded by Procambarus clarkii, while in water courses which do not harbor the crayfish, such as El Manayef drain and Fayed canal (West of Suez Canal), high densities of these vector snails were recorded.The present study is providing encouraging indication of the possible overcoming schistosomiasis and fascioliasis in Egypt and whole Africa by the freshwater crayfish Procombarus clarkii. New estimates of the Egyptian Ministry of Health indicated that the percent of infected people decreased significantly to only 4% comparing to 45% during 1960s.

Prevalence of Snail Vectors of Schistosomiasis in the Kpong Head Pond, Ghana

Abstract: Schistosomiasis, a parasitic disease caused by the blood fluke Schistosoma sp. became a serious public health problem in Ghana after the Volta River was dammed in Akosombo in 1964. The formation of the Kpong head pond, about 25 km below the Akosombo dam, as a result of a second dam built at Kpong became an active schistosomiasis transmission site. The Volta River Authority (VRA) recently began an initiative of combining manual clearing of aquatic vegetation with chemotherapy as a way of managing the disease. However, no scientific monitoring of the effect of aquatic weed clearing on the vector population is being conducted. The study was initiated in the Kpong head pond to provide baseline data for subsequent monitoring and impact assessment of the initiative. It involved sampling of the banks of the head pond for aquatic snails at six different sampling sites of 1 m2 each, chosen at 100 m interval along the shoreline. Physicochemical factors which affect aquatic snail population were also determined. Aquatic snails sampled were Bulinus truncatus , Bulinus globosus , Biomphalaria pfeifferi , Melanoides spp, Physa waterlotti and Pila sp. where the first three are intermediate host of the schistosoma parasite. The study revealed B. truncates as the most frequent occurring vector (71.0%), followed by Biomphalaria (12.0%) and B. globosus (6.1%) The mean numbers of vector snails sampled per m2 were B. Truncates 61/m2, B. globosus 5/m2, and B. pfeifferi 11/m2. The presence of aquatic weeds and favourable physicochemical conditions of the water were found to provide a conducive environment for the vectors to thrive and hence sustain schistosomiasis transmission in the head pond. It is, therefore, recommended that a 5-year period of studies be undertaken to assess the impact of manual clearing of aquatic weeds on the snail population.

Biological and physiological parameters of Bulinus truncatus snails exposed to methanol extract of the plant Sesbania sesban plant

Abstract: The effects of sublethal concentrations of methanol extract of sesbania sesban plant on survival rate, egg laying of Bulinus truncatus snails, hatchability of their eggs, infection rate with Schistosoma haemato- bium miracidia, cercarial production and certain physiological parameters of treated snails were stu- died. The sublethal concentrations of the tested plant extract (LC0, LC10 and LC25) caused considerable reduction in survival rates; egg production of B. runcates snails; hatchability of eggs as well as in the infectivity of Schistosoma haematobium miracidia to the snail. Also, the tested concentrations reduced the cercarial production per snail and the period of cer-carial shedding. The glucose level in haemolymph of exposed snails was elevated while the glycogen, pro-tein content and the activities of hexokinase (HK), pyruvatekinase (PK) and lactate dehydrogenase (LDH) showed a decrease in soft tissues when compared with the control group. It was concluded that the app lication of sublethal concentration of methanol ex- tracts of Sesania sesban may be helpful in snail con- trol as it interferes with the snails’ biology and phy- siology.

Application of Some Aqueous Plant Extracts as Molluscicidal Agents on Bulinus truncatus Snails in Sudan

Abstract: Although schistosomiasis is spreading in new areas in Sudan, there are no proper programmes of control adopted neither by the government nor by the international organization. The promising results of many indigenous plants as molluscisidal could be promoted to be used in the biological control. Plants are known to be manufacturing chemical substances that are used for own defense from attacks by insects, bacteria, fungi and viruses. These chemicals are the nature inventory that can be utilized against similar organisms. Laboratory evaluation of the molluscicidal of leaf extract from Calotropis procera and Nicotiana tabacum and the seed of Trigonella foenum plants were carried out against Bulinus truncatus snails. The results of mortality were statistically analyzed using probit analysis. The assessment of the lethal concentration for 50 and 95% of the snail was tested (LC50 and LC95). The low values of LC95 against adult, juveniles and egg masses of snails were recorded in Calotropis procera being 1100, 483 and 31ppm respectively. Comparing the LC95 values of the water extracts of the three plants against adult snails, showed high activity for Calotropis procera plant (1100ppm), followed by Nicotiana tabacum plant (1386ppm), as well as Trigonella foenum plant (2085ppm). These three plant extracts are recommended to be used as molluscicidal agents.

Urinary schistosomiasis transmission in Epe, an urban community of Southwest Nigeria

Abstract: Background: A survey of Schistosoma haematobium infection in Epe, an urban community in Lagos State, Southwest Nigeria, was carried out to ascertain the possibility that schistosomiasis, otherwise considered a rural disease, could reach urban populations. Materials and Methods: About 100 ml of voided urine samples from 200 pupils aged 6-13 years [109 (54.5%) males and 91 (45.5%) females], attending an Anglican primary school, Ebute Afuye, and a community primary school, Erepoto, were examined parasitologically for hematuria and S. haematobium ova following informed consent obtained from their parents/guardians. All samples were screened using polymerase chain reaction (PCR) amplification of the schistosome Dra1 gene. Fourteen Bulinus snails collected from the two sites, Ebute Afuye (6) and Erepoto (8), were screened for schistosome infection by the PCR amplification of the schistosome Dra1 gene. PCR-RFLP of the snails' its region was analyzed for species identification and a subregion of the cox1 gene from four infected snails (two from each site) was amplified and sequenced. Results: In the Anglican primary school, Ebute Afuye, and community primary school, Erepoto, 16% and 29% were positive for hematuria, and 16% and 17% had schistosome ova, respectively. PCR analysis showed that 57% and 40% were positive for the infection in Anglican primary school, Ebute Afuye, and community primary school, Erepoto, respectively. PCR screening of the snails confirmed that four from Ebute Afuye and three from Erepoto were infected with schistosomes. PCR-RFLP showed that all the 14 snails were Bulinus truncatus while phylogenetic analysis of the sequenced partial cox1 gene corroborated the PCR-RFLP results. Conclusions: There was a high prevalence of S. haematobium infection among the participants detected by PCR, which was able to detect infection in cases otherwise shown to be negative by hematuria. We also observed that B. truncatus is one of the snail species responsible for the transmission of urinary schistosomiasis in the Epe community. For national control programs, it is very important that trends in the prevalence and intensity of schistosomiasis in urban cities be monitored.

Habitat characteristics for different freshwater snail species as determined biologically through macroinvertebrate information.

Abstract: Macro-invertebrates including freshwater snails collected from 643 sites over 8 successive seasons among the River Nile, branches, main canals and certain drains in eight Egyptian Governorates. Thirteen snail species and one bivalve species were identified. The most distributed were Lanistus carinatus and Physa acuta while the most abundant were Cleopatra bulimoides and Physa acuta during the whole study. The sites that harbored each snail species in all the examined water-courses were grouped seasonally and their biological assessment was determined by their minimum and maximum total point similarity percentage to that of the corresponded reference site and mean of the total points. Habitats for most snail species attained minimum total point's similarity percentage less than 21% (very poor habitat) during autumn and winter then spring while during summer very poor habitat was harbored by only few snail species. P. acuta was the only survived snails in habitat which attained 0 as a minimum total point's similarity percentage during two seasons and L. carinatus and Succinea cleopatra during one season. With respect to medically important snails very poor sites constituted 23% of Biomphalaria alexandrina sites, 14% of Lymnaea natalensis and 9.4% of Bulinus truncatus sites. The studied macroinvertebrate matrices, total number of organisms, taxa richness, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) index, ratio of EPT index to chironomidae, ratio of scraper to filtering collector, contribution of dominant macroinvertebrate major group, comparison revealed descending tolerances from B. alexanrina followed by L. natalensis then B. truncates, but Hilsenhoff Biotic Index (HBI) showed the same tolerance to organic pollution.

Genetic variation within and between populations of hermaphroditic Bulinus truncatus tetraploid freshwater snails of the Albertine Rift, East Africa

Abstract: Genetic variability within and among Bulinus truncatus of the Albertine Rift freshwater bodies were assessed to investigate the degree of inbreeding and gene flow in the snail populations. The effect of ploidy on the genetic structuring of B. truncatus is also described. We characterized the genetic structure of seven B. truncatus populations from Lake Albert, Lake Kivu, and Katosho swamp in Tanzania using five polymorphic microsatellite loci. Genetic differentiation was quantified using pairwise FST values and Nei’s standard genetic distances. Different alleles were observed across all loci and genetic diversity was low although it varied greatly across populations; observed heterozygosity was, however, higher than the expected heterozygosity in three of the populations studied. Significant heterozygote deficiencies were observed coupled with significant linkage disequilibria in five populations for all the five loci examined in this study. We found significant genetic differentiation among the seven freshwater bodies; private alleles were observed across all loci indicating restricted or absence of gene flow between populations. Limited snail dispersal and the reproductive biology of B. truncatus are the major forces shaping the genetic variation observed. Low genetic variation within B. truncatus populations exposes them to a high parasite infection risk as predicted in the Red Queen hypothesis.

Molluscicidal Effects of Talinum Triangulare On Bulinus Truncatus

Abstract: The molluscicidal effects of Talinum triangulare from two locations in Nigeria on Bulinus truncatus were studied in the laboratory Snails were exposed for 96h to different concentrations of ethanolic extract of the plant root from Nsukka in Enugu State and Erei in Cross River State, Nigeria Those in dechlorinated water served as control On coming in contact with the test medium, the snails reacted by speedily crawling out of the containers Exposure of snails to Talinum triangulare concentrations of less than 300ppm showed only ovicidal activity while varying numbers of those exposed to 300ppm died as the exposure time increased The control group recorded no effects Snail recovery was only observed in concentrations less than 300ppm The LC 50 of the plant root extract from Nsukka in Enugu State and Erei in Cross River State decreased (ranging from 505-251ppm) as exposure time increased The molluscicidal activities (LC 50 ) of the ethanolic plant root extracts from the two locations were not significantly different (p> 005) The ethanolic plant root extracts of T triangulare may be a potential molluscicide in schistosomiasis control Key words : Molluscicide , Talinium triangulare , Bulinus truncatus, Schistosomiasis

Comparative study of the karyotypes and electrophoretic patterns of Biomphalaria alexandrina and Bulinus truncatus and the ova of their corresponding trematode hosts

Abstract: The karyotypes of Biomphalaria alexandrina and Bulinus truncatus were analyzed comparatively and classified on the basis of centromere position and the electrophoretic analysis of tissue protein has been used to determine the relationships between the ova of Schistosoma mansoni and Schistosoma haematobium and their respective snail hosts. The two species have the same diploid chromosome number, 2n = 36. The mitotic chromosomes of B. alexandrina are organized in three groups and consist of 8 metacentric pairs, 8 submetacentric pairs and 2 subtelocentric pairs of chromosomes. While, the karyotype of B. truncatus is organized in four groups and consists of 10 metacentric pairs, 4 submetacentric pairs, 2 telocentric pairs, and 2 subtelocentric pairs of chromosomes. Also, SDS-PAGE revealed 7 similar protein bands in the ova of S. mansoni and its snail host B. alexandrina and 5 similar protein bands in S. haematobium and its snail host B. truncatus. Additionally, the highest similarity coefficient was found between B. alexandrina and B. truncatus and their respective trematode hosts. It is hoped in the near future to identify targets in the snail host that interfere with parasite survival and develop alternate and/or novel methods to disrupt the transmission of schistosomiasis. Key words: Biomphalaria alexandrina, Bulinus truncatus, Schistosoma mansoni, Schistosoma haematobium, chromosomes, electrophoretic analysis.

Response of two vector snail species to infectivity with compatible and incompatible Schistosoma parasites

Abstract: Schistosomiasis remains one of the most prevalent parasitic infections and has significant economic and public health losses in many developing countries. Understanding the host/parasite interactions is important, since questions arise concerning the susceptibility of snails to infection by respective trematodes and their specificity and suitability as hosts for continued parasite development. Thus the aim of this research is to extend our knowledge about the biological basis of the snail/parasite relationship with the hope of finding novel ways to disrupt the transmission of this disease. In the current research the compatibility/incompatibility of two types of snails,Biomphalaria alexandrina and Bulinus truncatus with their target and nontarget miracidia (Schistosoma mansoni and Schistosoma haematobium) was investigated histopathologically and also by identifying some host defense mechanisms against the invading parasite by biochemical analyses through the measurement of lipid peroxides, and the antioxidant enzymes glutathione reductase, superoxide dismutase and catalase in these snails. The results showed that the parasites invading the incompatible snail species were immediately recognized by the host hemocytes and encapsulated at an early stage of snail penetration , while those infecting the compatibile snails were well developed as mother sporocysts. The obtained data also demonstrated that lipid peroxides were increased in snails exposed to the noncompatible parasite while the antioxidant enzyme levels were elevated in snails exposed to the compatible parasite indicating the capability of the respective parasites to overcome the defense mechanisms generated by its host. The infection rate between each type of snail and its compatible parasite was higher than with the non-compatible parasite. Results of these experiments strongly support the hypothesis that endogenous expression and regulation of larval antioxidant enzymes serve a direct role in protection against external oxidative stress, including immune-mediated cytotoxic reactions. This may open new areas for investigating new immuno or chemotherapies or vaccines against the enzymes or products that the parasite releases or needs to survive within its host.