Distribution of Freshwater Snalls in the Field Dittches (Abu Eshreens ) and Their Role In The Transmission of Schistosomiasis in Gezira Irrigated Scheme

No Thumbnail Available
Tahani Nagm Eldin, Hassan
Journal Title
Journal ISSN
Volume Title
This work was carried out in the abu eshreens of three minor canals, Gad El Ain, Wad El Magdi and Hassaballa, in addition to two special abu eshreens, one irrigating the gardens of Abu Usher Hospital and the other irrigating the Inspectors Houses’ in Abu Usher, in the northern part of Gezira Irrigation Scheme (the Scheme). The main objective of the study was to determine the distribution of freshwater snails in abu eshreens, and the different factors that might have affected the snail populations. Five genera of fresh water snails were found in the study abu eshreens. Three of them belong to the order Pulmonata. These were Biomphalaria pfeifferi, Bulinus truncatus and Bul. forskalii. The first two species are the intermediate host snails for the intestinal and urinary forms of schistosomiasis respectively. The last one is of no medical importance in the Sudan. The remaining two genera belong to the order Prosobranchata. These were Cleopatra and Melanoides snails. The intermediate host of human schistosomes were not widely distributed in the tudy area. This is probably due to the dredging of the three minor canals under the study just before the start of the study. Dredging not only deepened the canal and increased the water velocity, but also removed the vegetation that usually supports large populations of the snails. The distribution of the snails in abu eshreens was found to be affected by the physical characteristics of each canal. The ecological conditions prevailing in the canalisation system during the rainy season affect all freshwater species negatively. However, The ecological conditions and the physical characteristics of the canals, together, determine the distribution of freshwater snails in abu eshreens. It was concluded that abu eshreens do not play any role in the transmission of schistosomiasis in the Scheme Bulinus forskalii snails were found widely distributed in the abu eshreens and it dominated all other species. The snail was found in an abu eshreen where it was reported to exist 30 years ago. This indicated that certain abu eshreens are having optimal conditions and under such conditions, freshwater snails establish colonies of populations that can survive for several years. A laboratory experiment indicated that the snail is still refractory to infection with S. haematobium miracidia. The possibility to use the snail as a biological agent was discussed. The crop in the field and the presence of water in the field ditches for a long time affected the distribution of snails in abu eshreens. They were abundant in abu eshreens irrigating vegetables and cotton respectively and were few in abu eshreens irrigating groundnuts/sorghum and wheat plants
Distribution,Freshwater,Snalls ,Field ,Dittches ,Role,Transmission ,Schistosomiasis