Disclosed herein is an aqueous composition for inactivating sporulated and/or non-sporulated Coccidia parasites, wherein the composition includes, prior to the dilution of water； a) 15 to 115ppm chlorine dioxide and 10-25wt-% of an anionic surfactant having one or more C6 to C18 alkyl groups and one or more aryl groups, b) an acid solution including i) 1 to 5wt-% of a weak carboxylic acid and ii) 2 to 10wt-% phosphoric acid, and wherein the final composition has been diluted at a ratio, composition to water, or between 1:10 to 1:1000. Also disclosed is a method for preparing the aqueous composition as described above, by combining a) a chlorite part including an alkali metal chlorite, and b) an acid solution including i) 1 to 5wt-% of a weak carboxylic acid and ii) 2 to 10wt-% phosphoric acid, c) 10 to 25wt-% of the anionic surfactant, and subsequently diluting the composition at a ratio, composition to water, between 1:10 to 1:1000.
