Showing papers on "Bulinus truncatus published in 1987"

Distribution of freshwater snails in the river Niger basin in Mali with special reference to the intermediate hosts of schistosomes

Abstract: Snail surveys were carried out in various parts of Mali. All areas surveyed are part of the Niger basin being either affluents or irrigation schemes fed by this river. The snail species present varied greatly between areas. The following potential hosts of schistosomes were recorded: Biomphalaria pfeifferi, Bulinus truncatus, B. globosus, B. umbilicatus, B. forskalii and B. senegalensis.

Effect of calcium concentration on growth and egg laying of Helisoma duryi, Biomphalaria alexandrina, B. camerunensis and Bulinus truncatus (Gastropoda: Planorbidae)

Abstract: Etude des besoins en calcium de Helisoma duryi afin d'evaluer ses potentialites comme hote intermediaire competiteur en vue d'une lutte biologique dans les zones a schistosomiase endemique

Genetic variability of Schistosoma bovis cercarial production according to miracidial dose.

Abstract: Cercarial production related to miracidial dose variation with Schistosoma bovis strains from Sudan and Spain in Bulinus truncatus from Tunisia was studied. Results showed that an increase in the miracidial dose proposed to the host-mollusc (1 and 5 miracidia) gave rise to a decrease in cercarial productivity of Sudanese S. bovis and to an increase for Spanish S. bovis. It is concluded that this response difference to the miracidial dose variation depends on genetic characters peculiar to the parasite strain and represents a new aspect of genetic variability of schistosome populations.

The Effects of Isolation, Grouping and Population Density on Fecundity of Bulinus truncatus

Abstract: Summary Bulinus truncatus is the intermediate host of Schistosoma haematobium, a trematode parasite causing bladder bilharziasis in man. In the struggle against this disease, control of snail populations is an important goal and expansion of our knowledge of the reproductive activity of Bulinus is relevant in this regard. In this study the effects of various factors on the fecundity of Bulinus were investigated in specimens kept under continuous water refreshment conditions. The results are considered to be more indicative of the natural situation than results obtained under the current use of discontinuous water refreshment. Isolated snails produce considerably higher numbers of egg masses and eggs than grouped snails. The effect of grouping on isolated snails, and the reverse situation, is very rapid, being fully effective within one week. The increase in fecundity of isolated snails is most probably caused by the absence of copulatory activity, since transfer of semen is known to curtail egg laying in ...

[Comparative analysis of the rhythm of cercariae emergence in three strains of Schistosoma bovis (trematoda: Schistosomatidae)].

Abstract: A comparative experimental study of the rhythmic shedding of three geographic strains of Schistosoma bovis cercariae (Sardinian, Sudanese and Spanish) by Bulinus truncatus showed a significant difference in the emergence patterns. The results support the existence of a genetic variability of the emergence rhythms. The origin of the variability is discussed and could be found in the pastoral practice and the ecological characteristics of the different transmission foci.

Laboratory selection for increased tolerance to niclosamide in Bulinus truncatus (Gastropoda: Planorbidae) from Iran.

Abstract: Survivors of Bulinus truncatus from one exposure to niclosamide (Bayluscide) were used to establish the next generation in a five generation long laboratory selection for increased tolerance to niclosamide. In a comparison of the tolerance to the molluscicide between two original and two selected strains about 150 snails of each strain, divided into four size-groups, were exposed to aliquots of the same niclosamide solution on the same day and during the same time of the day. It was shown that five generations of relatively mild selection (30-50% survival) resulted in a significant increased tolerance to niclosamide in snails with only one exposure before start of the selection procedure. A comparison with published data indicated that the unselected strains did not change their tolerance to niclosamide during seven years of laboratory breeding. The strain exposed to niclosamide once in each of 16 generations showed an avoidance reaction to the chemical by crawling out of the water.

[Population dynamics of Bulinus truncatus in a focus of bilharziasis in Khemis-el-Khechna (Northern Algeria)].

Abstract: A demographic and epidemiological study of Bulinus truncatus was carried out in Hamiz river, transmission site of schistosomiasis in the Khemis-El-Khechna focus. The results shows direct influence of hydrographic factor on the populations dynamic which is characterized by irregular variations.