Health control policies in fish viral diseases.

Viral infections cause significant levels of mortality in intensive fish farming. There is no treatment, and, because vaccination is not yet feasible, prevention is only possible through fish health control measures or policies. The transportation of fish or fish products represents a major means of virus dissemination. For this reason, official systems of inspection and certification have focused mainly on exported shipments. A need for unanimity among the various systems has been recognized. Standardized rules and procedures have been encouraged by the international organizations (the FAO and the OIE) through the publication of technical documents, guidelines and codes. Health control systems can be effective, but they may be affected by many socio-economic factors and should always be associated with other preventive measures.