Effect of water and soil of marshilands along Changjiang river without snails on snails growth

  Objective   To explore the reason of no snails growing in long termin the marshilands along Changjiang river Nantong Rugao section and to explore the Shistosomiasis control strategies.

  Methods   Sample of water and soil from Changjiang River Rugao section contrast ing Yangzhou section was collected.Physical and chemical character of the two places was compared and analyzed.Hydrologic factor was investigated and analyzed.Snails were respectively breeded with water and soil of the two section in the room.The snails livability of the two in half a year was compared.Ratio of trigamous snails laying eggs and ratio of eggs hatching out was analyzed.Snails were breeded under control in the researched section and the snails livability was observed.

  Results   The Ca⁺⁺, Mg⁺⁺, total rigidity and chloride of water and SO₄^2- of soil from researched section was remarkable higher than that from contrasting section; the snails livability in half a year and the ratio of trigamous snails layingeggs of the two had no remarkable difference.Snails can grow in the researched section by artificial control.

  Conclusion   Tide-topping can obstruct snails spreading towards lower reaches of the river; Inspecting snails can be stopped to monitor it in the researched section with reduced cost, which would save health resources.