EFSA’s scientific advice on aquatic species susceptible to certain diseases

Following a request from the European Commission, the Panel investigated whether species indicated in Directive 2006/88/EC should, in the light of new scientific evidence, no longer be considered as susceptible, or if species other than those already listed should also be considered as susceptible. The results of this work can serve as a basis for the Commission to update the list of susceptible species farmed in Europe and/or imported into Europe, and to help establish the most appropriate disease control measures.

The Directive defines susceptible species as “any species in which infection by a disease agent has been demonstrated by natural cases or by experimental infection that mimics the natural pathways”. However, it is difficult to scientifically demonstrate whether or not an experimental infection mimics the natural pathways. Furthermore, it is sometimes difficult to distinguish between infection by a disease agent and contamination. EFSA therefore developed a set of scientific criteria for assessing susceptibility, which was subsequently applied to both the existing list of susceptible species and to other species which could be susceptible to the listed diseases.

Scientists were able to single out various species whose susceptibility is demonstrated by clear scientific evidence^[2] - referred to as Group I in the opinion - including some which are not currently part of the list ^[3]. The Panel recommends that the newly-identified susceptible species should be considered for possible inclusion in the list.

However, for a wide group of fish species - identified as Group II in the opinion - scientists were able to retrieve only partial evidence or no evidence at all suggesting susceptibility to specific pathogens^[4]. The Panel recommends further studies to investigate the susceptibility of the species in Group II.

The scientific opinion published today identifies a wide range of species, representing many groups of aquatic animals, susceptible to the 14 diseases of fish, molluscs and crustaceans specified in the list. The results of the scientific review also identify many diseases - such as Epizootic Ulcerative Syndrome, Viral Haemorrhagic Septicaemia and White Spot Disease – to which a high number of species are susceptible.

Furthermore, scientists indicated that some species are susceptible not only to one but to several disease agents. Scientists stressed that these species are likely to present a higher level of risk with regard to the spreading of disease – for example when they are traded – than the species which are susceptible to only one disease.

The work was carried out by the AHAW Panel which gathered and reviewed the most up-to-date, peer-reviewed scientific literature in the field. In carrying out this work, Panel scientists, supported by external experts developed a set of scientific criteria to assess pathways for infection and the response to such infections in the various species. These criteria were applied to assess the susceptibility of the species.

• Scientific Opinion: Aquatic species susceptible to diseases listed in Directive 2006/88/EC