Identification of Tilapia Lake Virus in Egypt in Nile tilapia affected by ‘summer mortality’ syndrome

Egyptian fish farms have faced unexplained mortality of tilapia during the summer months in recent years. Epidemiological surveys indicated that 37% of fish farmswere affected in 2015with an averagemortality rate of 9.2% and a potential economic impact of around US$ 100 million. Despite a number of researchers and organizations investigating potential causes results so far have been inconclusive. Meanwhile recent reports emerged of the presence of a new orthomyxovirus, Tilapia Lake Virus (TiLV) in Israel, which shares a border and migrating avifauna with Egypt. Tissue samples from seven farms affected by ‘summer mortality’ were tested at the University

of Stirling for TiLV. Samples fromthree of seven farms tested positive using PCR; the first time that TiLV has been

identified in Egypt. Sequence analysis yielded a TiLV sequence with 93% homology to the published TiLV sequence

described from Israel. More research is required to determine if TiLV is linked to ‘summer mortality’.