Showing papers on "Biomphalaria alexandrina published in 2001"

In vivo, attenuation of schistosome cercarial development and disturbance of egg laying capacity in Biomphalaria alexandrina using sublethal concentrations of plant molluscicides.

Abstract: The dry powdered of Sinapis arvensis, Thymelaea hirsuta, Callistemon lanceolatus and Peganum harmala showed molluscicidal activity against Biomphalaria alexandrina, specific intermediate hosts to Schistosoma mansoni. Effect of LC25 of dry powdered plant molluscicides on hexokinase (HK), glucose phosphate isomerase (GPI), AMP deaminase, adenosine deaminase and phenol oxidase (PO) of B. alexandrina was traced. C. lanceolatus showed the highest molluscicidal activity as it has the lowest LC50 compared to S. arvensis, T. hirsuta, and P. harmala. LC25 of the latter three plants resulted in more significant inhibition of HK, GPI, AMP-deaminase and PO than C. lanceolatus. Treatment of snails with LC10 of these plants markedly affected compatibility of B. alexandrina to S. mansoni infection. Significant decrease in cercarial production recorded in snails treated with sublethal concentrations of S. arvensis, T. hirsuta, and P. harmala. Remarkable impairment of the egg laying capacity of molluscicide-treated snails was also recorded. Correlation between activity levels of HK, GPI and AMP deaminase and compatibility to parasitic infection and role of PO in the egglaying capacity of these snail species were discussed.

Laboratory assessment of the molluscicidal activity of Commiphora molmol (Myrrh) on Biomphalaria alexandrina, Bulinus truncatus and Lymnaea cailliaudi.

Abstract: The molluscicidal properties of the oil extract of Commiphora molmol (Myrrh) were tested against Egyptian snail species: Biomphalaria alexandrina, Bulinus truncatus and Limnaea cailliaudi. The impact of the extract on the egg cluches of B. alexandrina and L. cailliaudi was also evaluated. Snails and their eggs were exposed for 24 and 48 hr at 22-26 degrees C to various concentrations of the extract. The results showed different susceptibilities B. alexandrina showed higher LD50 and LD90 (155, 195 ppm) than B. truncatus (50, 95 ppm) and L. cailliaudi (50, 85 ppm) after 24 hr exposure. 100% mortality was obtained for the egg cluches of B. alexandrina and L. cailliaudi at concentrations of 100 ppm and 75 ppm respectively. Lower concentrations were needed to obtain the same results after 48 hr. The present laboratory studies demonstrated that Myrrh has a molluscicidal effect on the snail intermediate hosts, particularly on their eggs. Field studies are recommended.

M0llusc1cidal activity of zygophyllumsimplex (family: zygophyllaceae) against bjomphalaria alexandrina and bulinus truncatus

Abstract: The molluscicidal activity of Zygophyllum simplex plant leaves powder on Biomphalaria alexandrina and Bulinus truncatus snails after 24 hours of exposure was evaluated under laboratory conditions. The results obtained indicated that the LC$o values for this plant were 42 ppm and 38 ppm and LC90 values were 65 ppm and 60 ppm for B. alexandrina and B. truncatus respectively. The sublethal concentrations (LCo, LCio and LC25) were 4.2, 27 and 34 ppm for Z?. alexandrina and 3.8, 25 and 32 ppm, for B. truncatus. Continuous maintaining of snails in sublethal concentrations (LCo, LCto and LC25) of Z simplex led to an increase in mortality rate of the snails which was significantly higher than that of the control group. The effect of the tested sublethal concentrations of Z simplex on infection of B, alexandrina with 5. mansoni miracidia was studied. The infection rate was significantly lower than that of control snails with reduction rates of 23.5%, 35.1% and 66.9% for snails exposed to LCo, LCjo and LCis, respectively. Prepatent period of exposed snails to LCo, LC10 and LC25 of Zygophyllum was prolonged to be 30.2 ± 2.4, 32.4 + 2.1 and 34.6 ±3.1 days compared to 28.6 ±3.6 days for the control group. Meanwhile, the duration of cercarial shedding was significantly shortened, being 22.8 ± 4.4, 18.3 ±4.9 and 10.5 ± 3.8 days for LCof LQo and LC25 respectively, compared with 44.2 ±4.8 days for the control snails. Highly significant reductions of total cercarial production per snails and per stimulant were also detected in experimental snails in comparison with the control group.

The effect of ecological parameters on the distribution of snail vectors of schistosomiasis.

Abstract: The infestation of the water courses showed 32.5% for Biomphalaria alexandrina and 8.75% for Bulinus truncatus. Ecological parameters, showed non significant variations in the water courses harbouring snail vectors and those free from snails except for conductivity in the habitats harbouring B. truncatus. This variation was more highly significant (p<0.001). Of the examined sites, 11.25% were harbouring B. alexandrina and Lymnaea natalenesis living together and 5% of the sites were harbouring B. truncatus and Physa acuta snails. Snail vectors were distributed with different degrees with aquatic plants reflecting the degree of species preference plants for snails' life.

Potential effect of Allium cepa and Allium sativum on haemolymph of Biomphalaria alexandrina, the intermediate host of Schistosoma mansoni.

Abstract: Biomphalaria alexandrina were fed on either Allium cepa or A sativum to study their effects on some biochemical parameters such as total proteins, free amino acids and liver enzymes (ALT, ALP and AST) on egg laying activity of the snails The results revealed that ALP was highly significantly reduced in haemolymph of snails that fed on either Allium cepa or A sativum Also, ALT and AST were highly significantly reduced in haemolymph of snails that were fed on A cepa while those fed on A sativum showed no change in ALT activity and a high significant increase in AST activity Total proteins were significantly decreased in haemolymph of all treated snails whereas variations in free amino acids contents were also observed The reproductive activity of snails fed on either Allium cepa or A sativum was highly affected In addition, growth rate of newly hatched snails fed on either A cepa or A sativum was affected Exposure of snails to water containing either A cepa or A sativum caused snail toxicity which may result from alterations in the snails' habitat

Effect of double infection with Schistosoma mansoni and Echinostoma liei on some physiological parameters of Biomphalaria alexandrina.

Abstract: The survival rate and fecundity of B. alexandrina were greatly influenced when exposed to either S. mansoni or E. liei miracidia. The snails exhibited much lower survival rate and fecundity when double exposed to both S. mansoni and E. liei miracidia than single exposure and control snails. The results indicated a disruption in the snail metabolism due to exposure to S. mansoni and E. liei miracidia and this effect was more pronounced in case of double exposure to the two parasites. Protein concentrations in hemolymph and tissues significantly reduced in all exposed snail groups than in the control group. A significant elevation in the levels of aspartate aminotransferase (ASAT) and alanine aminotransferase (Asat) enzymes was recorded in hemolymph and tissues of exposed snail than unexposed (control snails). The ASAT/ALAT ratios in tissue and hemolymph of single-exposed and unexposed B. alexandrina did not exceed 1, while it increased up to 1.18 in hemolymph of double exposed snails. There were significant increases in the levels of acid and alkaline phosphatases enzymes in exposed snails.

Effect of various foods on Biomphalaria alexandrina and Bulinus truncatus and their susceptibility to schistosome miracidia.

Abstract: The tested foods are tropical fish food (tetramine), rat food, blue green algae, dried lettuce leaves and a mixture of all these foods. The results indicated that feeding of B. alexandrina on a mixture of foods increased their growth and survival rates and their susceptibility to S. mansoni. Tetramine elevated the egg-laying capacity of snails compared to other tested foods. The hatchability of eggs of B. alexandrina fed on algae for a period of 16 weeks showed the highest rate followed by snails fed on a mixture of foods and then tetramine. B. truncatus maintained on a mixture of foods for 16 weeks, exhibited an increase in their growth, egg-laying, survival rates and recorded the highest infection rate with S. haematobium than other foods. Among the used foods, the hatchability of eggs of B. truncatus fed on tetramine for 16 weeks was the highest one.

Effect of ammonium chloride on Biomphalaria alexandrina and on its infection with Schistosoma mansoni and Echinostoma liei miracidia.

Abstract: Ammonium chloride (NH4Cl) has molluscicidal activity against B. alexandrina. The LC50 and LC90 recorded of this salt were found to be 90 ppm and 130 ppm, respectively. Maintaining of B. alexandrina at low concentrations of NH4Cl (5, 10, 15 and 20 ppm) greatly reduced their survival rate and fecundity. The net reproductive rate (Ro) [sigmaIx Mx] was deleteriously affected. This rate was significantly reduced than that of control snails in all tested snail groups. The reduction in Ro was 86.9%, 90.8%, 93.9% and 96.9%, respectively. The susceptibility of B. alexandrina to infection with S. mansoni and E. liei miracidia and infectivity of these two parasites were greatly reduced. Increasing the salt concentration increased this reduction. The magnitude of reduction in infection rate was lower in case of E. liei than that in S. mansoni indicating that E. liei is more tolerant to the effect of this salt than S. mansoni.

Cellular response to Schistosoma mansoni infection in Biomphalaria alexandrina strains selected for susceptibility and resistance.

Abstract: Exposure of juvenile and adult Biomphalaria alexandrina to Schistosoma mansoni miracidia resulted, typically, in three susceptibility patterns: a) non-infected snails; b) normal infections, and c) retarded infections. Under laboratory conditions, a vigorous resistant-type cellular response to invading miracidia was seen in the histological sections of non-susceptible snails. Accordingly, they were classified as resistant snails. Data pertaining to the influence of host size on suceptibility to S. mansoni indicates that adult snails (i.e. 10-20 mm shell diameter) were significantly less likely to harbour sporocysts than juvenile ones (i.e. 5-10 mm shell diameter). Cellular reaction to the infection varied with sporocysts location and length of infection. At 2 days post-exposure (DPE), most sporocysts were viable. Approximately 8-12% of the sporocysts had elongated shaped transverse constriction and were categorized "normal", while those showing no elongation were categorized "retarded". All remaining sporocysts at 4 DPE were categorized "dead", while at 30 DPE, most sporocysts were "amorphous" with eosinophilic masses. Although encapsulation of sporocysts never occurred in susceptible snails, haemocyte aggregations could sometimes be observed in the proximity of well developed sporocysts. In resistant snails, this cellular response continued to increase and resulted in the encapsulation of the sporocysts. In susceptible snails, the nucleus of secretory cells of the albumen cytoplasm were different in susceptible and resistant snails.

Determination of the compatibility between biomphalaria alexandrina and echinostoma liei using sds-page analysis of tissue soluble proteins

Abstract: S analysis of tissue soluble proteins of Biomphalaria alexandrina and rediae, cercariae, metacercariae and adult worms of Echmostoma liei was done for determination of the degree of compatibility between the snail and each of intramolluscan larval stages and adult worms of the parasite. The highest degree of similarity was observed between B. alexandrina and metacercanae of E. liei. However, the lowest degree of similarity was noted between B. alexandrina and adult worms of E. lieu On the other hand, the similarity coefficient between B. alexandrina and E. liei rediae was higher than that between the snail and E. liei cercariae.