| focality and seasonality of schistosoma mansoni transmission in the gezira irrigated area, sudan. | in the gezira irrigated area of central sudan, transmission of schistosoma mansoni was shown to be geographically focal, being concentrated near villages and small settlements. in a study during 1981 and 1982 of the entire area around a typical gezira village almost 90% of the biomphalaria pfeifferi snails carrying schistosome infections were found in one minor canal near the village. sites near smaller settlements some distance from the minor canals yielded few infected snails. the factors whic ... | 1985 | 4032530 |
| snails and aquatic vegetation in gezira irrigation canals. | all 38 minor canals in a limited area of the gezira irrigated area were surveyed four times over a 2-year period to determine the aquatic and semi-aquatic vegetation types found and their distribution. a more detailed 2-year study of the correlation between snail density and aquatic vegetation was carried out in 18 of these canals. a total of 22 different species of weed were recorded, with floating and submerged weeds being more widespread and dense in the clear, slow-moving water at the end of ... | 1985 | 4032532 |
| schistosoma mansoni (gezira) infection in biomphalaria pfeifferi snails from gezira and jebel marra. | the comparative susceptibility of biomphalaria snails from gezira and jebel marra to s. mansoni (gezira) was investigated. groups of laboratory-bred snails from the two localities were exposed to 0, 1, 2, 3 and 4 miracidia. the growth rate of the snails was followed over the experimental period by measuring the snails' shell size. sub-groups of infected snails were examined for daughter sporocyst counts by crushing of the snails. other groups of exposed snails were maintained until cercariae wer ... | 1985 | 4032534 |
| a large-scale snail control trial with trifenmorph in the gezira irrigation scheme, sudan. | a large-scale field trial was carried out during december 1973 to assess the effect of trifenmorph on bulinus truncatus and biomphalaria pfeifferi in 379 000 feddans ( approximately 159 000 ha) of the gezira irrigation system in the sudan. the commercial formulation used (frescon) is an emulsifiable concentrate containing 16.5% trifenmorph. five dispensers were used to add the commercial product to the water continuously for 7.5 days; 18 121 litres were used to treat 28.4 million m(3) of water. ... | 1976 | 1088406 |