Absence of viral hemorrhagic septicemia virus (VHSV) and infectious hemorrhagic necrosis virus (INHV) in a Tunisian fish farm: a case study.

Abstract

Beyond the obvious problems related to the sustainable management of wild stocks, current fish farming practices in the Mediterranean area entail important environmental risks and potential outbreaks of fish diseases linked to massive translocations across regional boundaries. Viral haemorrhagic septicaemia (VHS) and infectious hematopoietic necrosis (IHN) are well-known fish diseases caused by the VHSV and IHNV viruses, and positive cases are subject to obligatory reporting to the World Organisation for Animal Health (OIE). In August 2004, the OIE published the first record of a VHS outbreak in a sea bass (Dicentrarchus labrax) aquaculture facility on the coast of the Mediterranean Sea. However, D. labrax is not considered as a susceptible host species for viral hemorrhagic septicaemia according to OIE's International Aquatic Animal Health Code (2009) and VHSV was not previously reported in the Mediterranean. In this sense and given the high risk of disease translocation associated with farmed fish in marine aquaculture, the present study was aimed at investigating the presence of VHSV and IHNV in stocks of sea bass and sea bream (Sparus aurata) reared inside a Tunisian coastal fish farm. Cell culture, IFAT and RT-PCR were applied to screen for both VHSV and IHNV in 69 pooled samples of sea bass and 24 pooled samples of sea bream. All three techniques showed the absence of both viruses within fish at the selected site.