BIOSECURITY MANAGEMENTS TO CONTROL TILAPIA LAKE VIRUS AND BACTIERAL DISEASES IN TILAPIA FARMS

Biosecurity is a standard practice that aims to limit the introduction and spread of pathogen in the production environment. For tilapia production, recent emerging of viruses and bacterial diseases such as Tilapia Lake Virus (TiLV) and Streptococcus agalactiae have been reported in Nile tilapia and red hybrid tilapia in different parts of the world. These emerging pathogens associate with high mortality of 80-90% within 1-2 weeks after the disease has been observed. To limit the catastrophic loss of infectious diseases, implementation of biosecurity and control measures should be applied at the farm, regional, national and international levels. Such concepts that could be employed including the screen of live fish and broodstock using PCR or real-time PCR, restricting fish movement, applying disinfectants as a standard practice, fry vaccination, and eliminating potential vectors. Figure 1 illustrates the common practice of tilapia farming in Asia with the open cages in natural water resources. Risk of pathogen entry should be identified e.g. the movement of infected fish into the farm and nearby culture area (Fig 2). Importantly, the pathogens may spread horizontal and/or vertical with infected fish. For example, a recent study by our laboratory suggested that TiLV could be detected in the mucus of moribund tilapia and that infected virus could spread through fish mucus until 12 days post infection. Therefore, removing of moribund and dead fish will reduce the risk of disease transmission and prevent the spread of pathogens in the farm and region. Overall, applying a standard of biosecurity plan and control measures at the farm and national level should limit the sources of disease outbreak.