Outbreaks of Tilapia Lake Virus

At the end of May 2017, the Food and Agriculture Organization of the United Nations (FAO) issued a Special Alert warning against the Tilapia Lake Virus and its consequences.

The alert states that Tilapia Lake Virus (TiLV) presents a serious threat to the tilapia sector. According to FAO, tilapias are the second most important aquaculture species in terms of volumes produced, providing a key source of affordable animal protein, income to fish farmers and fishers, and domestic and export earnings.

The ten most important tilapia producers for 2015 were: China, Indonesia, Egypt, Bangladesh, Viet Nam, the Philippines, Brazil, Thailand, Colombia and Uganda. In 2015, world tilapia production amounted to 6.4 million tonnes, with an estimated value of USD 9.8 billion.

TiLV has now been reported in five countries on three continents: Colombia, Ecuador, Egypt, Israel and Thailand. It is likely that TiLV may have a wider distribution than is known today and its threat to tilapia farming at the global level is significant, FAO warns.

TilV poses no public health concern but threatens food security

An outbreak of TiLV threatens the livelihoods and food security of millions of people, particularly of highly vulnerable subsistence fishers and small fish farms, according to the FAO Special Alert. The disease is highly pathogenic, with no known control methods.

While the pathogen poses no public health concern, it can decimate infected populations. It poses a significant threat to both cultured and wild stocks of tilapia. Infected fish often show loss of appetite, slow movement, dermal lesions and ulcers, ocular abnormalities, and opacity of lens.

The outbreak should be treated with concern and countries importing tilapias should take appropriate risk-management measures - intensifying diagnostics testing, enforcing health certificates, deploying quarantine measures and developing contingency plans, according to FAO.

Currently, actively TiLV surveillance is being conducted in China, India, Indonesia and it is planned to start in the Philippines. In Israel, an epidemiological retrospective survey is expected to determine factors influencing low survival rates and overall mortalities including the relative importance of TiLV. In addition, a private company is currently working on the development of a live attenuated vaccine for TiLV.

In May 2017, The Network of Aquaculture Centres in Asia-Pacific (NACA) released a TiLV Disease Advisory and the World Organisation for Animal Health (OIE) released a Disease Card. The WorldFish Center also released a Factsheet entitled TiLV: what to know and do.

(FAO/ile)

Read more:
TiLV Special Alert (FAO)
Tilapia Market Reports (FAO)
TiLV Disease Advisory (NACA)
TiLV Disease Card (OIE)
Factsheet: TiLV: what to know and do (WorldFish Center)