scispace - formally typeset
Search or ask a question

Showing papers on "Biomphalaria alexandrina published in 1996"


Journal ArticleDOI
TL;DR: Different chemical characteristics of the signaling glycoconjugates could be the basis for the observed host specificity in miracidial host-finding in snail-conditioned water.
Abstract: The effect of snail-conditioned water (SCW) from Biomphalaria alexandrina, a pigmented and an albino strain of B. glabrata, and Lymnaea stagnalis on the host-finding behavior of miracidia of two Brazilian and one Egyptian strain of Schistosoma mansoni was studied. Miracidia of the Egyptian strain significantly preferred their suitable host B. alexandrina versus the other snail species with their behavior patterns of host location and their responses after contact with the host. However, miracidia of both Brazilian strains did not differentiate between SCW from three of the snail species; only the pigmented B. glabrata elicited weaker responses. The releasing cues of SCW for miracidial host-finding phases are macromolecular glycoconjugates. An analysis of SCW by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), blotting, and subsequent carbohydrate detection showed that the band patterns of glycoconjugates differed significantly among the four snail strains. Therefore, differing chemical characteristics of the signaling glycoconjugates could be the basis for the observed host specificity in miracidial host-finding.

42 citations


Journal ArticleDOI
TL;DR: Snails that are produced from snails previously exposed to low doses were more sensitive to the tested extracts, which may give primary indication of no possibility of inherited resistance.

34 citations


Journal Article
TL;DR: This is the first report on the infestation of irrigation and drainage systems at Giza, Qalyoubiya and Kafr El Shiekh Governorates, with Biomphalaria glabrata (the snail host of Schistosoma mansoni in the new world).
Abstract: This is the first report on the infestation of irrigation and drainage systems at Giza, Qalyoubiya and Kafr El Shiekh Governorates, with Biomphalaria glabrata (the snail host of Schistosoma mansoni in the new world). Identification of this snail species was based on morphometry of the shell, shape of the radular lateral teeth and presence of the characteristic renal ridge. B. glabrata snails collected from natural water courses in Egypt proved to be susceptible to a local strain of S. mansoni. These snails were infected by 52% versus 75% for Biomphalaria alexandrina (the only local host) under the same laboratory conditions. Meanwhile the periodic total cercarial production was higher in B. glabrata than in B. alexandrina (252 +/- 110 cercariae/snail versus 203 +/- 86 cercariae/snail, respectively). Differences in infection rate, length of schistosome incubation period, duration of cercarial shedding and cercarial production in various sizes of the two snail species are reported and discussed.

26 citations


Journal Article
TL;DR: Snail populations and parasite strains from different Governorates (Gize-Dakahlia) exhibited poor values of snail sensitivity and cercarial production with significant variations from those of the group of the same governorate.
Abstract: Biomphalaria alexandrina snails were collected from irrigation canals at Gize and Dakahlia Governorates. They were exposed to strains of Schistosoma mansoni from these localities. The snails showed different rates of susceptibility to the parasite. There was a high range of snail sensitivity to S. mansoni infection (53.9%-60.7%) when snail populations and parasite strains were from the same governorate. Supporting this was the high cercarial production from infected snails of these cases (288.2 cercariae/ snail/week of Dakahlia-Dakahlia group). However, snail populations and parasite strains from different Governorates (Gize-Dakahlia) exhibited poor values of snail sensitivity and cercarial production with significant variations from those of the group of the same governorate.

6 citations


Journal Article
TL;DR: In the natural irrigation system, cercariometry was significantly more sensitive in detecting transmission foci than snail sampling by a dip net and in the continuous operating centrifuge and water suction sampling technique, results suggest also strong seasonal differences in diurnal patterns of cercarial recovery.
Abstract: The recovery of Schistosoma mansoni cercariae was studied in experimental ditches and natural irrigation canals using a continuous operating centrifuge and a water suction sampling technique. Recovery of cercariae from static water in the ditches where caged infected Biomphalaria alexandrina snails were placed showed that cercariae recovered were more with increase of infected snails and decrease of water volume and were most abundant in the proximity of the snails which produced them. Shade or heavy vegetation cover reduced the recovery of cercariae. Results suggest also strong seasonal differences in diurnal patterns of cercarial recovery. An early morning peak with large number of cercariae occurred during hot weather while in cooler seasons cercariae appear in fewer numbers but persist for most of the day. Obtained information, beside contributing to knowledge of cercarial behaviour, should help to optimize taking water sample and consequently to increase efficiency of cercariometry techniques. In the natural irrigation system, cercariometry was significantly more sensitive in detecting transmission foci than snail sampling by a dip net.

4 citations


Journal Article
TL;DR: The two molluscicides affected more on the mortality of Biomphalaria alexandrina than Bulinus truncatus and Copper sulphate was more effective than Bayluscide on the fungal species of both snails.
Abstract: Biomphalaria alexandrina and Bulinus truncatus are the main vectors of human Bilharziasis in Egypt. The mycotic inhabitants of both control and treated snails were surveyed at 7 and 15 days intervals. The two molluscicides affected more on the mortality of Biomphalaria alexandrina than Bulinus truncatus. The highest population of zoosporic fungi was collected from Biomphalaria alexandrina, the lowest from Bulinus truncatus. Copper sulphate was more effective than Bayluscide on the fungal species of both snails. Achlya, Dictyuchus and Saprolegnia were the common genera while Leptolegnia caudata and Pythium ultimum completely missed from treated snails. The total colonies of zoosporic fungi were lowered after. 15 days of treatment. The two molluscicides inhibited the cell division of both tested snails.

3 citations


01 Jan 1996
TL;DR: Some extracts of Euphorbia helioscopia (Euphorbiaceae), Calendula micrantha (Compositae) and Azadriachta indica (Meliaceae) were screened for the control of Culex pipiens larvae and revealed that these plant extracts probably exhibit the same mode of action toward the pests tested.
Abstract: Some extracts of Euphorbia helioscopia (Euphorbiaceae), Calendula micrantha (Compositae) and Azadriachta indica (Meliaceae) were screened for the control of Culex pipiens larvae, the vector of Filariasis and Biomphalaria alexandrina snails the vector of Schistosomiasis in Egypt. These plants exhibit dual effect on both pests which share the same aquatic breeding habitat and are of medical importance. B. alexandrina snails were more susceptible than first instar larvae of C. pipiens toward all extracts of the plants tested. The acetone extracts of the three tested plants were the most active. The similarity of data of all fractions tested against both species revealed that these plant extracts probably exhibit the same mode of action toward the pests tested.

1 citations


Journal Article
TL;DR: The reproductive capacity of irradiated Biomphalaria and Bulinus snails was highly suppressed and this will interrupt Schistosomiasis transmission and the maximum survival periods of laboratory populations of Biomphaaria snails were less than those of field ones which means a high sensitivity of laboratory snails to X-ray.
Abstract: Biomphalaria alexandrina and Bulinus truncatus snails were exposed to sublethal doses 0.2, 3, 5, 10 and 20 rad of X-ray. The survival and reproductive rates of these snails were highly affected by these doses. The maximum survival periods of laboratory populations of Biomphalaria snails were less than those of field ones which means a high sensitivity of laboratory snails to X-ray. The reproductive capacity of irradiated Biomphalaria and Bulinus snails was highly suppressed and this will interrupt Schistosomiasis transmission. A deleterious effect of gametogenesis of irradiated Biomphalaria was histologically proved. After 3 weeks of snail irradiation with high dose (40 rad) the hermaphrodite gland became completely evacuated.

1 citations


Journal Article
TL;DR: A total of 1535 persons of different age, sex and occupation from 5 villages in Qalyoubia Governorate in Nile Delta were subjected to clinical, stool, urine and intradermal tests accompanied by a questionnaire, revealing decreased rates of schistosomiasis and snail infectivity.
Abstract: A total of 1535 persons of different age, sex and occupation from 5 villages (Tanan, El-Sad, Sandiun, Kalama and Taha-nob) in Qalyoubia Governorate in Nile Delta were subjected to clinical, stool, urine and intradermal tests accompanied by a questionnaire for 500 of them Snail vectors of Schistosome parasites were collected from 2 villages (El-Sad and Taha-nob) and snail densities in the waterways as well as the prevalence rate of infection with schistosomal cercariae were recorded The results revealed that the average prevalence rate of Schistosoma haematobium in the 5 cillages was 49% (range 23% - 71%) and that of S mansoni was 133% (range 114-144%) The overall prevalence of both types was 182% (range 137-214%) The average density of Biomphalaria alexandrina in the 2 village was 1647% and that of Bulinus truncatus was 75%, the ratio was 2:1 The infectivity with schistosomal cercariae was very low with an average of 25% in B Alexandrina and 15% in B truncatus Factors responsible for the decreased rates of schistosomiasis and snail infectivity were discussed

1 citations