EFFECT OF THIABENDAZOLE AS AN OVICIDE ON HELMINTH EGGS IN NIGHTSOIL

Abstract

The ovicidal activity of thiabendazole on helminth eggs in water and in nightsoil was examined by cultivation of these eggs after exposure to the drug. Embryonation of Ascaris eggs in both acid and alkaline buffered solutions was consistently inhibited at the concentration of 1.56 ppm in a 7-day exposure at 25C. The minimal effective concentrations of thiabendazole on Ascaris eggs in nightsoil at 5C, 15C and 25C were 400, 100 and 6.25 ppm, respectively, in a 3-day exposure, and 200, 25 and 3.12 ppm, respectively, in a 7-day exposure, while on Trichuris eggs they were 25, 6.25 and 1.56 ppm, respectively, in a 3-day exposure, and 12.5, 3.12 and 0.39 ppm, respectively, in a 7-day exposure. The minimal effective concentrations of thiabendazole on hookworm eggs in nightsoil were 1.56 and 0.78 ppm in both 3-day and 7-day exposures, respectively, at the exposure temperature of 15C. Pre-field test on the ovicidal effect of thiabendazole on the helminth eggs in nightsoil was carried out employing nightsoil tanks which contained different volumes of nightsoil ranging from 140 to 650 liters. Ascaris and Trichuris eggs were killed by thiabendazole at a concentration of approximately 50 ppm and hookworm eggs at a concentration of approximately 5 ppm after a 7-day exposure.