There is disclosed herein a composition for treating extracellular parasitic infections, the composition comprising one or more of the following combinations: at least one quinolone or fluoroquinolone together with at least one tetracycline, iodoquinol, an azole or imidazole; or at least two agents selected from the group consisting of iodoquinol, thiazolidones, tetracycline, nitroimidazoles, cotrimoxazole and diloxanide furoate. There is also disclosed herein a method for treating extracellular parasitic infections in a vertebrate in need of said treatment, wherein said treatment comprises administering to said vertebrate a therapeutically effective amount of (i) a composition comprising a quinolone or fluoroquinolone together with a pharmaceutically acceptable carrier or (ii) a composition of the invention or (iii) a combination of at least one quinolone or fluoroquinolone optionally together with at least one tetracycline, iodoquinol, an azole or imidazole; or (iv) a combination of at least two agents selected from the group consisting of iodoquinol, thiazolidones, tetracycline, nitroimidazoles, cotrimoxazole and diloxanide furoate.