Country report aquatic animal health in Malaysia

Abstract only.The fisheries sector of Malaysia plays a significant role in economic development. It provides employment, foreign exchange and protein supply for the country. In 2017, aquaculture production in Malaysia was 427,022 tonnes, a 4.8 % increase compared to 2016. The increase was driven by population growth, rising demand for seafood and a levelling of production from capture fisheries. However, the rapid growth of aquaculture has been source of anthropogenic change on a massive scale. Aquatic animals cultured in high density are exposed to environment stress leading to diseases. Among major diseases occur in Malaysia are TILV and Streptococcosis in Tilapia, Vibriosis in grouper, and APHND and EHP in shrimp. Losses due to these diseases were reported as USD 0.1 billion for APHND in 2011, MYR 1 million due to Streptococcosis in 2002 and USD 7.4 million in Vibriosis outbreak in 1990. Currently the use of chemicals to overcome these diseases by farmers has led to increase concerns on food safety of food fish. Thus, Malaysia has implemented strict biosecurity measures in fisheries practices to secure not only fish health but also food safety for the consumers. This paper aimed to discuss the status of fish diseases and national diseases response and surveillance in Malaysia

Current status and advances of fish vaccines in Malaysia

Fish diseases have a significant negative influence on the Malaysian aquaculture industry. Since the 1980s, the sector has grown in size, which has resulted in a rise in the prevalence of infectious outbreaks affecting both freshwater and marine cultured fish species. Demand for commercially available fish vaccinations is predicted to increase as infectious disease outbreaks continue to occur. In Malaysia, aquaculture vaccine research and development (R&D) are still in its infancy, with most efforts concentrating on producing vaccines against bacterial infections, most notably streptococcosis, vibriosis, andmotile Aeromonas septicemia. Despite several attempts, no homegrown vaccine has been effectively introduced into the manufacturing pipeline to date. At the moment, only three imported aquatic vaccines have received full permission, a far cry from the 314 and 60 vaccines licensed in the poultry and porcine industries, respectively. This review will describe recent findings regarding the development of aquaculture vaccines for certain fish species and diseases in Malaysia. In our opinion, R&D on fish vaccines is critical to the aquaculture industry’s viability

Pathogenicity of different betanodavirus strains in Asian Seabass (Lates Calcarifer) under temperature fluctuation stress

Viral Nervous Necrosis (VNN) disease caused by betanodavirus infection is responsible for mass mortality in many marine cultured fish species. . Fish can acquire the disease by either horizontal or vertical transmission. Malaysian local betanodavirus strains were obtained from National Fish Health Research Centre, Penang and cultured in E-11 cell line. The isolates are Bawal Emas (BE), AVA and KL 22. Fifty-percent tissue culture infective dose (TCID50) calculations for all the isolates were conducted to evaluate the concentration of the virus. In this study, three hundred and sixty healthy seabass juveniles (5 ± 2g) with size two to three inches were obtained from Marine Fish Aquaculture Research Division, Terengganu was divided equally in eight tanks that represent four treatment groups with duplicates; Group 1 (AVA strains), Group 2 (BE strains), Group 3 (KL22 strains) and Group 4 (control). All the fish were observed daily for any clinical changes and mortality that occurred. Upon clinical signs appearing and mortality, the fish were slaughtered immediately and subjected to a polymerase chain reaction (PCR), cell culture and histology. The experiment was terminated after thirty days period. TCID 50 for all the tested strains are as follow; KL 22 = 104 TCID50/mL, BE = 107 TCID50/mL and AVA = 106 TCID50/mL. KL22 strain was found to have the highest TCID 50 followed by AVA and BE. Similarly, the highest mortality was also recorded in the group challenged with the KL22 strain which also has the highest TCLD 50. All the dead and sick fishes tested positive for PCR. However, the histology finding indicated no vacuolation found in the cell suggesting an acute infection has occurred

Persistent detection of Tilapia lake virus in wild tilapia and tinfoil barbs.

Background and Aim: One of the emerging viral diseases in freshwater fish is Tilapia lake virus (TiLV), which infects all stages of fish and results in mass mortalities. Previously, a TiLV case was detected in the wild environment in Malaysia that involved tilapia and tinfoil barb. Hence, this study aimed to determine the presence of TiLV in wild tilapia (Oreochromis niloticus) as well as tinfoil barbs (Barbonymus schwanenfeldii) at the similar lake after the initial outbreak in year 2017. Materials and Methods: Both fish species were sampled from this lake at a month interval for two years and subjected to TiLV detection using reverse transcriptase-polymerase chain reaction and cell culture isolation. Concurrently, bacterial isolation and water quality measurements were performed to deduce their correlation with TiLV occurrence. Other wild fish species and mollusk were also occasionally sampled during the fish inventory activity at this lake. The fish’s weight, length, and associated clinical signs were noted throughout the entire study period. Results: Mortality was not observed throughout the whole study period, and results indicated a moderate to high prevalence of TiLV infection in both tilapia and tinfoil barbs. There was no correlation between TiLV infection with the isolation rate of opportunistic bacteria such as Aeromonas spp., Plesiomonas spp., and Edwardsiella spp. in the study site. At the same time, the Pearson correlation test revealed a moderate negative correlation between the water pH with the presence of TiLV (R=−0.4472; p<0.05) and a moderate positive correlation between the water iron content with the monthly detection of Aeromonas spp. in wild tilapia. This is contrary to tinfoil barbs, where there was a moderate negative correlation between the water iron content with the monthly isolation of Aeromonas spp. (R=−0.5190; p<0.05). Furthermore, isolation of TiLV on cell culture-induced viral invasion was resulted in the cytopathic effects. Conclusion: Our results suggest that the wild fish may harbor TiLV for an extended period following a massive die-off event in 2017 without any obvious clinical signs and mortality. The persistency of viruses in the wild may need continuous and effective control as well as prevention strategies. Keywords: Malaysia, Tilapia lake virus, tinfoil barbs, wild tilapia

Assessment of antibacterial activity of fresh garlic juice extract against Vibrio spp. isolated from hybrid grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus): An in vitro study

We assessed the antibacterial activity of fresh garlic juice extract against Vibrio spp. isolated from hybrid grouper (Epinephelus fuscoguttatus x Epinephelus lanceolatus). The disc diffusion method was conducted to evaluate five concentrations of fresh garlic juice extract against Vibrio alginolyticus, Vibrio vulnificus, and Vibrio parahaemolyticus. The tested concentrations are 20%, 40%, 60%, 80%, 100%, and oxytetracycline (OTC) antibiotic as a positive control, while absolute ethanol as a negative control. Results from the disc diffusion study revealed 100% and 80% garlic juice extract have higher inhibition zone against V. alginolyticus and V. vulnificus compared to OTC. The inhibition zone against V. parahaemolyticus was slightly less when 100% garlic juice extract gave an equal inhibition zone with OTC and smaller in other concentrations. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were also studied, which resulted in the lowest MIC value was V.alginolyticus (0.011%) followed by V.vulnificus (0.023%) and the highest is V. parahemolyticus (0.045%). Similarly, the lowest MBC value was V. alginolyticus (0.023%) followed by V. vulnificus (0.045%) and the highest is V.parahemolyticus (0.09%). The results revealed that fresh garlic juice extract was effective against the test bacteria and showed the potential of using fresh garlic juice extract treatment as an antibacterial agent to treat vibriosis in hybrid grouper fish