A new study in the Journal of Fish Diseases has identified instances where tilapia infected with tilapia lake virus (TiLV) passed the disease onto their offspring without cohabitating. This finding suggests that the virus can be transmitted vertically, as well as through the cohabitation of infected and susceptible fish.
Tilapia lake virus is a viral disease that infects tilapia globally. The disease causes skin lesions and ulcers, eye abnormalities, reduced schooling behaviour and mass mortalities. Tilapia that have been infected with the virus but survive are immune from further TiLV infections. As it stands now, there is no treatment or vaccine for the disease, but this may change in the future.
In this study, researchers were able to isolate TiLV RNA in the liver and gonads of broodstock males and females. Infective virus was isolated in the cell line. When testing two-day-old fry for the presence of TiLV, results indicated that they had inherited the virus from broodstock.
In light of these results, the researchers emphasised the need to adhere to strong biosecurity measures. By prioritising prevention and ensuring that the virus does not get introduced to the farm site, the disease will not proliferate. The researchers also suggested that TiLV-free broodstock be developed in order to limit vertical transmission.
The original abstract can be read here.
Thumbnail credit: Blue Ridge Aquaculture.