May 9, 2017

Tilapia farmers in Asia-Pacific are facing the threat of a disease that has started to manifest in Thailand.

In a disease advisory, the Network of Aquaculture Centres in Asia-Pacific (NACA) identified the disease threat as Tilapia lake virus, or TiLV, an aetiological agent causing the mass die-offs of farmed fish including tilapia in Israel and Ecuador.

"This has been reported as a newly emerging virus that causes syncytial hepatitis of tilapia (SHT)," NACA said, adding that as of last year, countries affected by this emerging tilapia disease included Israel, Ecuador, Colombia and Egypt.

It said that recently, disease outbreaks among cultured tilapias occurred in Thailand, wherein high cumulative mortalities (20-90%) were observed and recorded. It added that TiLV was putting at risk the US$7.5-billion global industry, especially in the top tilapia-producing countries in the Asia-Pacific region including China, the Philippines, Thailand, Indonesia, Laos and Bangladesh.

"Thirty-two outbreaks were investigated during 2015-2016 involving large number of deaths of unknown cause among farmed tilapia (Oreochromis niloticus) and red hybrid tilapia (Oreochromis spp.). Histopathology (of the liver showing similar signs to SHT), transmission electron microscopy, in-situ hybridisation and high nucleotide sequence identity to TiLV from Israel confirmed that these outbreaks were caused by TiLV", NACA stated.

Tilapias are an increasingly important and inexpensive source of fish protein and are one of the most popular species for aquaculture in several regions including the Asia-Pacific. The top 10 producing-countries include China, Egypt, Philippines, Thailand, Indonesia, Laos, Costa Rica, Ecuador, Colombia and Honduras.