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PubMed1976

Influence of diet on breeding and infectivity in mass cultivation of Bulinus truncatus.

Under well defined laboratory conditions as troughs, room temperature, humidity, water, and air supply Bulinus truncatus was bred and kept. In a feeding trial high protein diet consisting of powdered mice pellets, commercial tropical fish food and lettuce was compared to poor protein diet of lettuce alone. Higher yield of clutches, eggs and cercariae were observed in the rich protein diet group, Bulinus and Biomphalaria Snail seem to be influenced by diet in the same way.

Animals↗
PubMed1961

Biological studies on the snail, Bulinus truncatus, in Central Iraq.

This paper presents some results of field and laboratory studies on Bulinus truncatus, the snail intermediate host of urinary bilharziasis in Iraq, made in 1958 as part of the work of the WHO Bilharziasis Control Project in that country.Observations on the linear distribution and size composition of Bulinus populations in the canals of central Iraq indicate that molluscicides might most suitably be applied in May before the entire snail population reaches breeding size, or early in November when most snails are juveniles. However, laboratory experiments appear to show that isolation of individual bulinid snails does not diminish, but may actually increase, their egg-laying capacity in comparison with that of grouped snails; this suggests that, even if the snail population were drastically reduced by treatment of the canals and all further importation of snails rendered impossible, the snail population would nevertheless soon renew itself from the few individuals remaining.Results are also given of laboratory experiments on egg masses, hatching and growth of B. truncatus and on the egg-laying of random populations of that snail.

Animals↗
PubMed2004

[Experimental study of the compatibility between Schistosoma haematobium and two species of Bulinus in Cameroon].

A study on the compatibility between Schistosoma haematobium from three remote localities (Mourtourwa, Gounougou and Kékem) and four populations of Bulinus truncatus (Gounougou, Ngaoundéré, Bertoua and Kékem) and four populations of B. globosus (Mourtourwa, Ouroudoukoudje, Bafia and Yaoundé) was undertaken in order to estimate the risk of extension of urinary schistosomiasis in Cameroon. First generation of offspring from wild Bulinus was exposed to miracidia liberated by schistosome eggs extracted from patient urine. Between the 25th and the 60th day post-infestation the number of snails still alive, the number emitting cercariae and the prepatent period duration were noted. Results showed that all B. truncatus samples were susceptible to the three strains of parasite whereas only B. globosus of Mourtourwa and Ouroudoukoudje were susceptible to S. haematobium from Mourtourwa. The schistosome infection rate was then significantly higher in B. truncatus and the prepatent period significantly lower than in B. globosus. The compatibility characterised by a high infection rate and a low prepatent period was significantly better in homopatric couples than in allopatric combinations. The results suggested that B. truncatus might be potentially more implicated than B. globosus to the extension of the urinary bilharziasis in Cameroon.

Animals↗
PubMed1996

New possible molluscicides from Calendula micrantha officinalis and Ammi majus. II. Molluscicidal, physiological, and egg-laying effects against Biomphalaria alexandrina and Bulinus truncatus.

In the present study, the effects of CuSo4 and crude extracts of the different parts of Calendula micrantha officinalis and Ammi majus, i. e., leaves, stems, roots, and flowers, on adult Biomphalaria alexandrina and Bulinus truncatus were investigated. Generally, leaves and flowers of both plants exhibited marked potency in killing the snail vectors of schistosomiasis. The recorded LC50 and LC90 values showed that C. officinalis was more toxic to both snails than A. majus, and B. truncatus are more sensitive to the extracts of both plants than B. alexandrina. 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. Moreover, prolonged exposure to the sublethal concentrations of A. majus have a definite lethal effect on the egg laying and longevity of both snails. Also, treatment with sublethal doses of both plants clearly inhibited the transaminase activity (ALAT, ASAT), diminished the total protein content, and increased markedly total lipid contents in the hemolymph of both snails.

Alanine Transaminase↗
PubMed1977

Neurosecretion in the basommatophoran snail Bulinus truncatus (Gastropoda, Pulmonata).

The neurosecretory system of the freshwater snail Bulinus truncatus was investigated. With the Alcian blue-Alcian yellow (AB/AY) staining method at least 10 different types of neurosecretory cells (NSC) were distinguished in the ganglia of the central nervous system. The differences in staining properties of the NSC - with AB/AY the cells take on different shades of green and yellow - are borne out at the ultrastructural level: the NSC types contain different types of neurosecretory elementary granules. The neurosecretory system of B. truncatus is compared to that of Lymnaea stagnalis, the species which has received the most attention among the pulmonates. It appears from the comparison that the systems of both species show many similarities, although some differences are also apparent.

Alcian Blue↗
PubMed1984

The prepatent period and cercarial production of Schistosoma haematobium in Bulinus truncatus (Egyptian field strains) at different constant temperatures.

The developmental time of Schistosoma haematobium in Bulinus truncatus snails (field strains) was determined in the laboratory at different constant temperatures between 18 and 32 degrees C. The basic relationship between the length of the minimum prepatent period (y, in days) and the temperature (x, in degree C) is given by the hyperbolic formula y = 295/(x-15.3), 15.3 being the theoretical "developmental null point" and 295 the constant time-temperature product. The shortest prepatency was 17-19 days at 30, 31 and 32 degrees C; at 18 degrees C, cercarial development required at least 106-113 days. The maturation time frequently exceeded the possible minimum by several weeks. No schistosome matured in our experiments at 17 degrees or 33 degrees C. The cercarial release per snail at weekly exposures showed a maximum at 25 degrees C with a geometric mean of 109 cercariae (95% confidence limits 79-149), decreasing to 8 (2-30) at 18 degrees C and 62 (38-100) at 32 degrees C. The absolute maximum of cercariae shed by one snail during 5 h "stimulation" was 2,150 in a 25 degrees C batch, 48 at 18 degrees C and 529 at 32 degrees C. The epidemiological application, the prognosis of the transmission period and the estimation of the transmission potential in relation to climatic conditions are discussed.

Animals↗
PubMed1989

The influence of Calicophoron microbothrium on the susceptibility of Bulinus tropicus to Schistosoma bovis.

A total of 480 snails were collected from 3 habitats on the Mau Escarpment, Kenya, and were identified as Bulinus tropicus. Of the 351 snails examined alive in London, 75 were infected with Calicophoron microbothrium, 39 with C. microbothrium and Schistosoma bovis, 1 with S. bovis, 24 with other species of trematodes and 212 were uninfected. Examination of digestive glands of B. tropicus either uninfected or infected with both C. microbothrium and S. bovis demonstrated that it is possible to differentiate between parasite and host enzyme activity using glucose phosphate isomerase. However, malate dehydrogenase enables a much clearer differentiation between the enzyme activity of the schistosome and that of the amphistome. Laboratory snail infection experiments demonstrated that it is possible successfully to infect B. tropicus with S. bovis if the snails have previously been exposed to miracidia of C. microbothrium.

Animals↗
PubMed1995

A comparative study of the shedding of cercariae of Schistosoma haematobium in newborn Bulinus truncatus.

A comparative study of the shedding of cercariae of Schistosoma haematobium was performed in Bulinus truncatus and Planorbarius metidjensis individually exposed to 5 miracidia in their first 72 h of life. No significant difference was noted between the mean values of the two snail groups concerning the prepatent period duration (53-57 days at 24 degrees-26 degrees C), the patent period duration (41 days for B. truncatus, 70 days for P. metidjensis), or the total number of cercariae (1,499 per B. truncatus, 1,935 per P. metidjensis). Successive periods of heavy and low production were encountered in the shedding of cercariae; however, the periodicity was identical in the two snail species (25-27 days) and the emergence of cercariae peaked between 11 a.m. and 1 p.m.

Animals↗
PubMed1985

Bulinus tropicus from Central Kenya acting as a host for Schistosoma bovis.

One hundred and twelve snails were collected from two habitats on the Mau Escarpment, Kenya and were provisionally identified as Bulinus tropicus from the characteristics of their shell and soft parts, chromosome number (n = 18), electrophoresis of egg protein on cellulose acetate strip and isoelectric focusing of AcP, GPI, HBDH, MDH and PGM digestive gland enzymes. Of the 55 specimens examined alive in London, 10 were infected with amphistome and schistosome larvae, 9 with amphistome larvae and the remainder were uninfected. The GPI and MDH separations of known infected snails showed two distinct areas of activity: host and parasite. Individual hamsters were exposed to schistosome cercariae emanating from each snail with a double infection (apart from one which died prematurely) and examination of the resulting adult worms showed that all were monomorphic for AcP with a band of enzyme activity at pH 6.45, characteristic of Schistosoma bovis. Examination of eggs found in two infections proved to be S. bovis in shape and size. Exposure of laboratory-bred snails of B. tropicus from the Mau Escarpment and other populations of B. tropicus proved negative. Thus, it is suggested that the presence of the amphistome infection may have a suppressive effect on the immune system of the snail, thereby allowing S. bovis to develop.

Animals↗
PubMed1980

Histochemical studies of some enzymes in the tissues of the schistosome vector snail Bulinus truncatus (Audouin) with special reference to the effects of a molluscicide. I. Dehydrogenases.

The histochemistry of five dehydrogenases, namely isocitrate, succinate and lactate dehydrogenases and NADH and NADPH diaphorases were studied in the tissues of the schistosome vector snail, Bulinus truncatus, before and after treatment with the molluscicide Frescon. Isocitrate and succinate dehydrogenases showed their strongest activity in the respiratory epithelia, while lactate dehydrogenase showed a high level of activity in the tissues that are known to be capable of glycolysis. Following the administration of Frescon, a marked loss in the activity of isocitrate dehydrogenase and NADPH diaphorase occurred. It is postulated that the molluscicide toxin may interfere with cellular respiration, especially in the exposed areas of the body.

Animals↗
PubMed1980

Histochemical studies of some enzymes in the tissues of the schistosome vector snail Bulinus truncatus (audouin) with special reference to the effects of a molluscicide. II. Hydrolases.

A comparative study of six hydrolases, acid and alkaline phosphatases, aryl sulphatase, beta-glucuronidase cholinesterase, and non-specific esterase, was carried out on the tissues of normal healthy and Frescon-treated Bulinus. The presence and activity of these enzymes in the tissues of normal animals were taken to indicate the probable functions of the tissues concerned. Frescon administration caused inhibition of acid phosphatase and also induced the release of cholinesterase and non-specific esterase in some tissues. It is concluded that the most important effects of Frescon on snail physiology are the disorganization of neuronal function and disturbance of olfactory activity.

Acid Phosphatase↗
PubMed1990

Population dynamics model for Bulinus globosus, intermediate host for Schistosoma haematobium, in river habitats.

A mathematical model is developed that describes the population dynamics of the freshwater snail Bulinus globosus, an intermediate host of Schistosoma haematobium. The model is developed from field data recording abundance changes, recruitment rates, and mortality rates for adult snails in river habitats in Zimbabwe. Rate of recruitment into the adult population is dependent on temperature, incorporating a time lag to allow for growth to adult size. Mortality rate is also a function of temperature. A temperature-dependent model provides a useful description of changes in abundance during the dry season. Long-term population fluctuations are greatly affected by spates (flooding) associated with heavy rainfall. An estimate is made of the frequency and effects of spates. A simulation model that allows variable annual rainfall predicts fluctuations in snail abundance over two orders of magnitude over timescales of ten or more years. The role of density-dependent factors and the long-term persistence of the population are discussed. B. globosus population dynamics can be described as 'density vague'.

Animals↗
PubMed1996

Variation within the internal transcribed spacer (ITS) of ribosomal DNA genes of intermediate snail hosts within the genus Bulinus (Gastropoda: Planorbidae).

Species within the genus Bulinus are responsible for transmission of schistosomes within the Schistosoma haematobium group. In order to provide a molecular insight into the species relationships within the genus, genetic variation between species representing the four species groups was assayed by Polymerase Chain Reaction (PCR) amplification of the ribosomal Internal Transcribed Spacer (ITS) region followed by Restriction Fragment Length Polymorphism (RFLP) analysis of this product with six restriction enzymes. This PCR-RFLP methodology detected considerable variation within the ITS region indicating that restriction profiles will be useful as genetic markers for identification purposes. The complete ITS1 spacer was sequenced for B. globosus, B. cernicus and B. truncatus. There were numerous nucleotide differences between taxa mainly insertions and deletions. Nucleotide divergence was calculated between species from the restriction profiles: the B. truncatus/tropicus complex and B. reticulatus group were most similar which were in turn more closely related to the B. africanus group than to the B. forskalii group. The nucleotide divergence between the species groups is substantial and questions the placement of these groups within the same genus.

Animals↗
PubMed1995

Geographic compatibility of the freshwater snail Bulinus globosus and schistosomes from the Zimbabwe highveld.

Populations of Bulinus globosus were sampled from two rivers, 60 km apart, in northern Zimbabwe, and offspring from each geographic strain reared in the laboratory. Schistosomes were harvested from each strain and also maintained in the laboratory. Cross-infection experiments were conducted, whereby snails of both geographic strains were exposed to parasites of both geographic strains. Compatibility was found to be related to: (i) the geographic origin of the snail, and (ii) an interaction between the geographic origin of snail and parasite, such that sympatric combinations of snails and parasites produced a greater proportion of compatible infections than allopatric combinations. Cercarial output of infected snails was found to be related to the geographic origin of the parasite, but not of that of the snail. It is suggested that, as the snails used were laboratory bred and naive to schistosome infection, differences in snail-schistosome compatibility were genetically determined, rather than an adaptive response. This study supports earlier work which suggests the existence of geographic compatibility amongst natural populations of snails and trematodes, indicative of either increased infectivity by the parasite, or decreased resistance by the snail.

Animals↗
PubMed1979

Enzyme analyses of Bulinus africanus group snails (Mollusca: Planorbidae) from Tanzania.

38 population samples of snails of the Bulinus africanus group, collected from three separate areas of Tanzania, have been examined. Enzymes in crude digestive gland extracts of individual snails have been analysed by isoelectric focusing in polyacrylamide gels. The enzymes studied were: malate dehydrogenase (MDH); phosphoglucomutase (PGM); glucosephosphate isomerase (GPI); acid phosphatase (AcP) and hydroxybutyrate dehydrogenase (HBDH). Samples of B. nasutus were clearly differentiated from other species and enzyme differences were apparent between samples from the lake and coastal areas. Similarly, although clear distinctions could not always be made, samples of B. africanus, B. globosus and B. ugandae were characterized by their enzyme types. Individual variation was detected within populations and the significance of enzyme polymorphisms in relation to identification has been considered. No correlation was found between snail enzyme type and susceptibility to Schistosoma haematobium or S. bovis.

Acid Phosphatase↗
PubMed1984

Dynamics of schistosoma haematobium infection in a Gambian community. II. The effect on transmission of the control of Bulinus senegalensis by the use of niclosamide.

Niclosamide was used to interrupt transmission of Schistosoma haematobium by Bulinus senegalensis in seasonal rainwater pools for a period of three years. Snail populations were progressively reduced to approximately 1% of the numbers in untreated pools. There was little or no evidence of acquisition of new infection by children in the area during the period of intervention. The intensity of infection in a cohort of children initially under 10 years old followed for three years fell by more than 50%, while there was a ten-fold increase in a similar group in a nearby untreated area. The mean annual cost (1982) of control per head of the population protected was pound 0.50 (US $0.89).

Bulinus↗
PubMedDate not supplied

A laboratory study on the possible use of Helisoma duryi in the biological control of Bulinus africanus, intermediate host of Schistosoma haematobium.

In order to evaluate the possible use of Helisoma duryi as biological competitor of Bulinus africanus, life-tables were compiled for these two snail species maintained either in the presence of each other, or separately. Population parameters were calculated from these life-tables and it was found that H. duryi had a higher innate capacity of increase, net reproduction rate and growth rate as well as a longer lifespan and reproductive period than Bu. africanus. Furthermore, the biological potential of Bu. africanus was found to be adversely affected in the presence of H. duryi. It was concluded that the latter might be capable of replacing Bu. africanus in certain freshwater habitats and that field trials ought to be undertaken in South Africa.

Animals↗