Marine aquaculture in southern Europe is an expanding industry, in which production has been focused on gilthead sea bream, Sparus aurata and European sea bass, Dicentrarchus labrax. In an intensive aquaculture system, where fish are reared at high densities , infectious agents are easily transmitted between individuals and causes serious economic losses. Vaccines can provide soon result in their extensive use and vaccination is an integrated part of fish farms. Vaccine strategy demonstrated a positive impact in the risk reduction of antibiotic-resistant infections.
Since the early 1980s, Italy playing a major role in the Mediterranean marine aquaculture and production of fish increased from the 1980s to the early 2000s. The most important species cultured are European seabass (Sparus aurata ). According to FAO's data, marine species represent the third segment for production in weight and value . Aquaculture has developed a wide range of bacterial diseases that caused both major production issue and animal welfare difficulties. In marine aquaculture, fish are reared in an open aquatic environment and interaction with pathogens is impossible to avoid. Initially infectious diseases were controlled almost exclusively by a large use of antibiotic-medicated food. This practice has led to antibiotic resistance development of bacterial pathogen, resulting in a higher dose requirement for therapy. Actually, in Italy only five antimicrobial agents are licensed in fin fish production. Commercially vaccines available for marine bacterial diseases are: Vibrio anguillarum serotypes 01 and 02, V. ordali i, and Photobacterium damselae subsp. p iscicida. Vibriosis is a common disease in sea bass and has led to significant economic losses to date. Photobacteriosis mainly occurs in larvae and juveniles of cultured gilthead sea bream during the warm water period. Generally, vaccination strategy has been defined in base of which diseases to vaccinate against, vaccine type and the timing of vaccination.
Despite the availability of commercial vaccine, in Italy vaccination is still scarcely
adopted and, when used, is only for a one treatment. Most of fish vaccines are delivered by intraperitoneal injection for adult and bath for juveniles. Oral administration is the most appealing method: there is no handling of the fish, which reduces stress , and is suitable for mass immunization. However, few oral vaccines are commercially available, due to the increased quantity of antigen required and the limited duration of protection.
An effective vaccines strategy has been proven to enhancing production efficiency by increasing growth rate and food conversion efficiency. The development of fish vaccines is an interaction between research, the pharmaceutical industry and regulatory authorities.
An effective vaccine strategy demonstrated a positive impact in reducing the role of major bacterial diseases and risk of antibiotic-resistant infections.