Effects of Schistosoma mansoni cercarial concentration and length of exposure on infection of mice in a simulated running water environment

Abstract

The relationship between Schistosoma mansoni cercarial concentration and length of exposure on the infection of mice was examined experimentally in the Laboratory. Mice were exposed at laboratory temperatures to 1000, 10,000 and 50,000 cercariae per liter of water at lengths of exposure of 15, 30, and 60 minutes respectively. A running water environment was simulated using transparent rubber hose and an aspirator bottle acted as a water reservoir. The set-up served as the infection channel. Low cercarial concentration and exposure time gave low worm burdens while prolonged exposure of mice to high cercarial concentrations gave high worm burdens. On the other hand, low cercarial concentration but long exposure times gave high infection rates with low worm burdens while high cercarial concentration and short exposure times gave high worm burdens but low infection rates. The epidemiological significance of this pattern of infection is extrapolated to humans and the consequences discussed.





Key words: Schistosoma mansoni, Cercarial concentration, Mice, Worm burden.


Journal of Aquatic Sciences Vol.17(1) 2002: 50-54