The invention relates to the use of microspheres as adjuvants in the production of a vaccine against scuticociliatosis. The invention provides a vaccine containing spherical chitosan microspheres and a copolymer of methyl vinyl ether and maleic anhydride, that act as an adjuvant, the microspheres being covered with an antigen of a membrane of a pathogenic turbot parasite, the scutiociliate Philasterides dicentrarchi (synonym of Miamiensis avidus). The vaccine can induce powerful immune responses and an increased protection in the turbot against scuticociliatosis, when it is administered parenterally, improving the protection induced by vaccines using oleaginous adjuvants containing metabolisable oils, but without generating unwanted side effects in the fish.
