ABSTRACT
We evaluated the effect of niclosamide treatment and the additional cleaning of basins and pools on the density and infection rate of Bulinus truncatus within the irrigation network of Oudaya. The period prior to molluscicide treatment [January-May] revealed a mean density of 151 snails/m2 in 1995-96 and 127 snails/m2 in 1997-98. After cleaning had started, the mean density prior to molluscicide treatment fell to 84 snails/m2 in 1999-2000. After molluscicide treatment, densities dropped to very low levels only rising again from October. In November 1999-96 mean density reached 150 snails/m2 but after cleaning started in 1997-98 this only reached 80 snails/m2; in 1999-2000, when cleaning was undertaken 3 months before and after molluscicide treatment, it reached only 18 snails/m2. From 1995 to 1996, the infection rate rose slightly [4.54% to 5.44%], but, from 1997, there was a significant drop [3.13% to 2.16%]