Showing papers on "Biomphalaria alexandrina published in 2011"

Bioactivity of miltefosine against aquatic stages of Schistosoma mansoni, Schistosoma haematobium and their snail hosts, supported by scanning electron microscopy

Abstract: Miltefosine, which is the first oral drug licensed for the treatment of leishmaniasis, was recently reported to be a promising lead compound for the synthesis of novel antischistosomal derivatives with potent activity in vivo against different developmental stages of Schistosoma mansoni. In this paper an in vitro study was carried out to investigate whether it has a biocidal activity against the aquatic stages of Schistosoma mansoni and its snail intermediate host, Biomphalaria alexandrina , thus being also a molluscicide. Additionally, to see whether miltefosine can have a broad spectrum antischistosomal activity, a similar in vitro study was carried out on the adult stage of Schistosoma haematobium, the second major human species, its larval stages and snail intermediate host, Bulinus truncutes. This was checked by scanning electron microscopy. Miltefosine proved to have in vitro ovicidal, schistolarvicidal and lethal activity on adult worms of both Schistosoma species and has considerable molluscicidal activity on their snail hosts. Scanning electron microscopy revealed several morphological changes on the different stages of the parasite and on the soft body of the snail, which further strengthens the current evidence of miltefosine's activity. This is the first report of mollusicidal activity of miltefosine and its in vitro schistosomicidal activity against S.haematobium. This study highlights miltefosine not only as a potential promising lead compound for the synthesis of novel broad spectrum schistosomicidal derivatives, but also for molluscicidals.

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).

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.

Impact of Asparagus densiflours and Oreopanax Guatemalensis plants and Difenoconazole Fungicide on Biochemical Parameters of Biomphalaria Alexandrina Snails

Abstract: In this study, the most effective agent was Difenoconazole (Score) followed by Asparagus densiflours then Oreopanax guatemalensis plants against Biomphalaria alexandrina snails. The high concentrations of the three tested agents caused a remarkable reduction in hatchability percent of B. alexandrina eggs than the low concentrations. The sublethal concentrations (LC10 and LC25) of both A. densiflorus and Score have more destructive effect on the survival, growth and reproductive rates of the juvenile snails than the corresponding concentrations of O. guatemalensis plant. Different sublethal concentrations (LCo and LC5) of the three agents caused a remarkable elevation in the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes of the snails after the 1 st week of the exposure. The sublethal concentration LC5 of the three tested agents caused pronounced effect on the alkaline phosphatase (ALP) and acid phosphatase (ACP) activities after the 2 nd weeks of the exposure. Total protein, albumin, globulin and albumin/ globulin (A/G) ratio in hemolymph of snails exposed to sublethal concentration LCo of the three tested agents, are differently affected after the 1 st and 2 nd week of the exposure. The histological examinations demonstrated a severe damage in both secretory cells and digestive cells especially in case of Asparagus densiflours and Score.

Impact of the photosensitizers hematoporphyrin coated gold nanoparticles on biomphalaria alexandrina snails

Abstract: The present study was done using two concentrations of the photosensitizer Hematoporphyrin coated Gold Nanoparticles (HpdGNP3) (5x10–6 , 5x10–5 mole/dicemeter–3), to evaluate their efficacy on survival rate, egg-laying capacity of Biomphalaria alexandrina snails and on histological deteriorations in their hermaphrodite gland. B. alexandrina snails were incubated for 12 hours at each tested concentration in the dark, thereafter they were exposed to direct sunlight (336.2 W/m2) for either 2 or 4 hours followed by 24 hours of recovery. Control snails were treated with these concentrations without exposure to light irradiance. Another experiment was carried out simultaneously and the snails were left for 4 weeks of recovery to evaluate their egg-laying capacity (Mx). The results indicate that 5x10–5 Mdm–3 (HpdGNPs) with 4 hours of exposure sunlight suppressed the survival rate of B. alexandrina snails by 50%. Meanwhile, control snails incubated with 5x10–5 Mdm–3 HpdGNPs were not affected and still alive (100%). For snail’s fecundity (Mx), treated snails laid low number of eggs throughout the recov-ery period (4 weeks), in comparison with that of control ones. The highest value of Mx for snails treated with 5x10–5 Mdm–3 Hpd coated GNPs was recorded at the 3rd week of recovery period, being 6.7 eggs/snail, compared to 37.6 eggs/control snail. This has a negative reflect on the reproductive rate (Ro) of treated snails as it was reduced under these conditions by 76.6% and 86.1%, respectively.Histological tests re-vealed injuries in spermatocytes, oocytes, several degenerations of B.alexandrina hermaphrodite gland then evacuations in many gonad’s cells which severely suppressed their capacity for egg-laying. It is concluded from the present work that exposing B. alexandrina snails to sublethal concentrations of the photosensiter Hpd coated GNPs (12 hours incubation, 4 hours exposure to 336.2 W/m2) significantly reduced their reproductive capacity that may have a negative reflect on schistosomiasis transmis-sion.

Biological studies on Biomphalaria alexandrina snails treated with Furcraea selloa marginata plant (family: Agavaceae) and Bacillus thuringiensis kurstaki (Dipel-2x)

Abstract: Effect of the dry leaves powder water suspension of the plant Furcraea selloa marginata, belonging to family Agavaceae and Bacillus thuringiensis kurstaki (Dipel-2x) was evaluated against non-infected and Schistosoma mansoni-infected Biomphalaria alexandrina snails as well as their efficacy against the free larval stages of S. mansoni. The obtained results indicated that the LC50 and LC90 values after 24 hrs exposure were 53.66 & 84.35 ppm for F. selloa marginata and 392.3 & 483.64 ppm for B. thuringiensis kurstaki against adult B. alexandrina snails, respectively. The plant F. selloa marginata and B. thuringiensis kurstaki have a larvicidal activity against S. mansoni larvae (miracidia and cercariae), the plant F. selloa marginata was more toxic against larvae than B. thuringiensis kurstaki, the miracidia were more sensitive towards the toxic action of the tested agents than cercariae and the mortality percent of miracidia and cercariae is directly proportional to the time and the tested concentrations. The results revealed that the tested sub-lethal concentrations (LCo, LC10 and LC25) reduced the survival, growth rates and egg laying capacity of both non-infected and S. mansoni-infected snails during 12 weeks of exposure in comparison with their control group. The hatchability percent of B. alexandrina eggs of one, three and six days old exposed to LCo, LC10, LC25, LC50 & LC90 concentrations of F. selloa marginata and B. thuringinesis kurstaki, significantly decreased by increasing their age and the tested concentrations. Exposing B. alexandrina snails to sub-lethal concentrations of the tested agents for 24 hours either pre-, during or post exposure of snails to S. mansoni miracidia caused a marked reduction in the infection rate and decreased the mean total number of shedding cercariae/snail. Also, elongated their prepatent period (cercarial incubation period) and shortened the duration of cercarial shedding in comparison with their control group. Under semi-field conditions the more time of exposure to the concentration (LC90= 84.35 ppm) of the plant F. selloa marginata the more mortality among snails. The mortality rates of the snails were 0%, 2%, 18% and 30% at 3, 6, 12 and 24 hrs post exposure, respectively.

Impact profenophos (pesticide) on infectivity of Biomphalaria alexandrina snails with schistosoma mansoni miracidiaand on their physiological parameters

Abstract: Profenophos is an organophosphorus pesticide which are used effectively against cotton insects and mites.The present work was carried out to evaluate the molluscicidal activity of pesticides (Profenophos) against Biomphalaria alexandrina snails. Also, the effect of sublethal concentrations of pesticide on the infection of B. alexandrina with Schistosoma mansoni and some enzymes of energy metabolism were studied. The results showed that the infection of B. alexandrina with schistosoma mansoni was greatly reduced after exposure to LC0, LC10, LC25 of pesticide and also, reduction in number of cercariae per snail during the patent period and in the period of cercarial shedding. The present study indicated that the increase in levels of aminotransaminases, acid phosphatase and alkaline phosphatases enzymes in haemolymph and soft tissue of snails and the activity level of lactate dehydrogenase, hexokinase and pyruvatekinase was also significantly reduced in response to treatment.

Genotyping Natural Infections of Schistosoma mansoni in Biomphalaria alexandrina From Damietta, Egypt, with Comparisons to Natural Snail Infections From Kenya

Abstract: The distribution of Schistosoma genotypes among individuals in snail populations provides insights regarding the dynamics of transmission and compatibility between schistosome and snail hosts. A survey of Biomphalaria alexandrina from Damietta (Nile Delta, Egypt), an area subjected to persistent schistosomiasis control efforts, provided only 17 snails infected with Schistosoma mansoni (6.1% overall prevalence), each shown by microsatellite analysis to have a single genotype infection. By contrast, recent studies of uncontrolled S. mansoni transmission foci in Kenya revealed that 4.3% Biomphalaria pfeifferi and 20–25% Biomphalaria sudanica snails had multiple genotype infections. Compared with the 3 Kenyan populations, the Egyptian population of S. mansoni also showed a lesser degree of genetic variability and was genetically differentiated from them. We suggest that tracking of genotype diversity in infected snails could be further developed to serve as an additional and valuable independent indi...

Cryptostegia Grandiflora Affecting Compatibility of Biomphalaria Alexandrina and Biomphalaria Galabrata to Infection With Schistosoma Mansoni With Emphasis on Some Hematological Effects

Abstract: Cryptostegia grandiflora showed considerable mollluscicidal effect against Biomphalaria alexandrina and Biomphalaria galabrata intermediate host of Schistosoma mansoni. The effect of Cryptostegia grandiflora on the infection rate and morphology and number of snail haemocytes were studied under light and electron microscope. The sublethal concentrations (LC0, LC10, LC25) of the Latex aqueous solution of C. grandiflora were 0.88, 4.4 and 5.6 ppm for B. alexandrina and 3.5, 6.6 and 8.3 ppm for B. galabrata respectively. The susceptibility of B. alexandrina and B. galabrata snails, maintained at LC10 of Latex solution for 3-days perior miracidial exposure, to infection with S. mansoni was greatly reduced by 55.5 % and 58.9 % in comparison with control groups 66.7 % and 14.6 % respectively. Light microscopic investigation recorded that there are three types of haemocytes distributed in the haemolymph of B. alexandrina and B. galabrata snail. These cells are distinguished morphologically according to their shape, size and number. These cells are named granulocytes (50.9 %), hyalinocytes (19.1 %) and ameobocytes (30 %) in case of B. alexandrina and (28.4 %), (20.9 %) and (50.7 %) in case of B. galabrata respectively. After exposure to LC10 of C. grandiflora for three days cause a significante decrease in mean number of granulocytes in B. alexandrina and B. galabrata being (43 %) and (25 %) with a percentage reduction 15.5 % and 12.1 % respectively. This mean number of cells after exposure of snails to S. mansoni miracidia becomes 42 % and 26.3 % with a percentage reduction 17.4 % and 7.5 % in both snail species respectively. There was a high percentage reduction in the number of granulocytes of B. alexandrina and B. galabrata snails after exposure to infection and LC10 of C. grandiflora at the same time being 29.6 % and 18.0 % respectively. While in the case of amoebocytes cells, the mean number showed a highly significant increase after exposure to S. mansoni miracidia being 47.0 % and 55.9 % with increasing percent 56.7 % and 10.1 % in B. alexandrina and B. galabrata snails respectively. This mean number reached to 44.1 % and 61.0 % when B. alexandrina and B. galabrata exposed to LC10 of C. grandiflora for three days then exposure to Schistosoma mansoni miracidia with increasing percent 47.1 % and 20.3 % respectively. Electron microscopic examination showed apoptotic effect, nuclear chromatin fragmentation vacuolated cytoplasm and fagocytosis characters are seen clearly in amoeboied cells.

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.

Effect of ethanolic extract of Dalbergia sissoo plant parts on Biomphalaria alexandrina snail, the intermediate host of Schistosoma mansoni

Abstract: This study evaluated, using replicated laboratory bioassays, the toxicities of the ethanolic extracts ofDalbergia sissoo (family Leguminosae) fruits, leaves, roots and stem bark against adult Biomphalaria alexandrina, the snail intermediate host of Schistosoma mansoni in Egypt and their egg masses. Adult snails (6 to 8 mm in diameter) and viable 24 h-old embryonated egg masses were separately exposed to seven different concentrations (6.25 to 400 ppm) of extracts for 24 h. The LC50 and LC90 values of test extracts for adult snails and egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity on both adult snails and egg masses (24 h-LC90 value 34.4 and 38.6 ppm, respectively). Mortalities of eggs were manifested at the gastrula/exogastrula and or the pre-hatch snail stage of development. Ethanolic extract of the fruits was the most active with 100% mortality at 50 mg/l, followed by those of the leaves (at 100 mg/l), roots (at 200 mg/l) and stem bark (at 400 mg/l). Their respective 24 h-LC50 and LC90 values for B. alexandrina egg masses were 10.8 and 38.6 ppm, 18.5 and 68.3 ppm, 20.4 and 88.4 ppm, 36.8 and 144.6 ppm. The percentage of dead embryos at all stages increased with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoofruits to embryonated egg masses of B. alexandrina is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs. Key words: Dalbergia sissoo, Biomphalaria alexandrina, Schistosoma mansoni, egg masses.

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.

Identification of various Biomphalaria alexandrina strains collected from five Egyptian governorates using RAPD and species-specific PCR techniques

Abstract: The first generation of Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta) were sub-jected to species-specific PCR assays and the results showed that snails collected from the field were B. alexandrina, and there was no evidence for the pres-ence of B. glabrata. The snails were subjected also to RAPD- PCR technique. The results showed that dif-ferent fingerprints with each B. alexandrina strain were produced with varying numbers of bands rang-ing in size from 123.6 to 796.6 bp depending on the snail strain and the primer used. Many specific bands were obtained with the four primers in each strain. Primer OPA-1 amplified the highest number of spe-cific bands (26 bands) and gave the highest poly-morphism among the primers used (100% polymor-phism). The estimated similarity coefficients among B. alexandrina strains based on the RAPD-PCR pro-files ranged from 0.56 to 0.72. The highest similarity coefficient (0.72) was recorded between the strains of Ismailia and Kafr El-Sheikh, while the lowest coeffi-cient (0.56) was reported between the strains of SPSC and Ismailia.

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.

Tissue Responses Exhibited by Biomphalaria Alexandrina Snails from Different Egyptian Localities Following Exposure to Schistosoma Mansoni

Abstract: Snails’ susceptibilities to infection with Schistosoma mansoni were determined through observation of infection rates, total cercarial production and tissue responses of the first generation (F 1 ) of Biomphalaria alexandrina snails originally collected from different Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). B. alexandrina snails from Schistosome Biological Supply Center (SBSC, TBRI), Giza, Egypt were used as a reference control group. S. mansoni miracidia from SBSC were used for snail infection. Snails’ responses towards penetrating S. mansoni miracidia were compared between groups. The emergence of cercariae for a three-month period and the calculation of survival and infection rates, in control (Schistosome Biological Supply Center-SBSC) and infected snails were evaluated. The results indicated SBSC and Giza snails showed a greater susceptibility to infection and lower mortality rates. In addition, at 6 and 72 hrs post-exposure to miracidia all the snail groups showed no difference in the anatomical locations of sporocysts. The larvae were found in the head-foot, the mantle collar and the tentacles of the snails. Sporocysts showed normal development with low tissue reactions in SBSC and Giza snail groups infected with S. mansoni miracidia (Giza origin). However, in Fayoum, Kafr El-Sheikh, Ismailia and Damietta snail groups, variable tissue responses were observed in which numerous hemocytes made direct contact with S. mansoni larvae forming capsules. The results suggested that, different responses of B. alexandrina snail’s hemocytes towards S. mansoni are related to the degree of susceptibility of these snails. So this is important in planning the strategy of schistosomiasis control.

Study the prey preference of some aquatic insects for different snails under the laboratory conditions

Abstract: The study of five aquatic insects (predators), adults of two hemipterous species, Limnogeton fieberi Mayr, Sphaerodema urinator Duf., and nymphs of three Odonatous species, Anax imperator Leach, Crocothemis erythraea Brulle and Ischnura pumilio Charp. on four species of snails (preys) exist in its natural habitat at Qena, Bulinus truncates Audouin, Biomphalaria alexandrina Ehrenb, Cleopatra bulimoides Olivier and Melanoides tuberculata Muller. in non choice experiment under laboratory conditions, the result indicated that the first preference for attack to all predators was directed towards B. truncates. And the last preference was B. alexandrina. Except, L. fieberi, the last preference was C. bulimoides.