A method for detecting infectious hypodermal and haematopoietic necrosis virus in a biological sample, comprising the step of amplifying conserved segment of the virus in a biological sample by a first polymerase chain reaction using a first primer set having or at least 95% complementary to nucleotide sequences as set forth in SEQ ID NO: 1 and SEQ ID NO: 2; and contacting the amplified conserved segment with a second primer set having or at least 95% complementary to nucleotide sequences as set forth in SEQ ID NO: 3 and SEQ ID NO: 4 in a second polymerase chain reaction.