Virucidal effects of common disinfectants against tilapia lake virus

Abstract

Tilapia lake virus (TiLV) is an emerging virus associated with high fish mortality and economic losses. This study investigates the virucidal effects of the following disinfectants (active ingredients) on TiLV: 2.5 ppm iodine, 10 ppm sodium hypochlorite (NaOCl), 300 ppm hydrogen peroxide (H2O2), 80 ppm formalin and 5,000 ppm (0.5%) Virkon®. Factors that affect the disinfectants’ efficacy, including temperature, contact time and soiling (organic matter) interference, were examined under conditions mimicking natural aquaculture practices. TiLV inactivation of higher than 5 log10 TCID50 ml−1 was achieved after 10 min and at 28°C for all disinfectants except formalin; similar inactivation levels were reached by NaOCl and Virkon® at 10 min and 4°C. Extended exposure to formalin from 10 to 60 min at 28°C rendered more than 5 log10 inactivation. Increasing synthetic organic matter in the water to mimic soiling interference reduced the efficacy of NaOCl, iodine and H2O2 when tested at 10 min and 28°C; however, Virkon® still achieved more than 5 log10 inactivation. This study demonstrates that most common disinfectants effectively reduced viral loads to minimum levels. To limit the spread of TiLV in aquaculture farms and related facilities, the appropriate use of such disinfectants should therefore be promoted and implemented.

Tilapia lake virus: The story so far

“…While formalin at 80 ppm required a longer incubation of 60 min at 28°C for complete inactivation. However, NaOCl, iodine and H 2 O 2 showed reduced efficacy when the level of synthetic organic matter present in the water was increased to mimic soiling interference (Jaemwimol, Sirikanchana, Tattiyapong, Mongkolsuk, & Surachetpong, 2019). Another study has also shown that TiLV is susceptible to buffered povidone–iodine complex and chlorine (Soto, Yun, & Surachetpong, 2019).…”

Persistence of Tilapia tilapinevirus in fish rearing and environmental water and its ability to infect cell line

“…Alternatively, the application of disinfectants to treat water should be applied to prevent the risk of TiLV contamination. Recent studies showed that the most common disinfectants are very effective in inhibiting TiLV (Jaemwimol et al., 2019; Soto et al., 2019). Importantly, a basic knowledge of how the virus spreads in the fish population is required to minimize outbreaks or control the disease.…”

Improving tilapia biosecurity through a value chain approach

“…Disinfectants should be safe for use around aquaculture systems and sufficient to kill pathogenic agents of concern on the farm. Commonly used disinfectants include iodophors (e.g., Wescodyne, Betadine) and Virkon Aquatic, which are effective against most aquatic bacterial and viral pathogens affecting tilapia 102 . Strict security should also be enforced at both in‐land and cage culture systems to restrict the movement of visitors and ensure compliance with biosecurity protocols 18…”