Search

This article reports the antibiotics sensitivity and pathogenicity of Aeromonas veronii 5L isolated from diseased red hybrid tilapia. The antibiotic sensitivity of A. veronii 5L was determined towards 13 antimicrobial agents. Then, the bacterial inoculums ranging between 0 and 106 CFU/mL were used for intraperitoneal challenge in red hybrid tilapia juveniles. Aeromonas veronii 5L showed resistance to ampicillin, streptomycin and sulfamethoxazole/trimethoprim. Following intraperitoneal exposure, mortality was observed as early as 24 h post infection leading to a total of 56.7% cumulative mortality at 10² CFU/mL, and 66.7% from 10³ to 106 CFU/mL. Clinical signs and gross lesions including abdominal distension, detachment of scales and ulceration on the body surface, inflammation around the operculum and based of fins, hemorrhage of internal organs, and accumulation of fluid in abdominal cavity. Histopathological examinations revealed generalized congestion of the brain, necrotic hepatocytes, generalized tubular necrosis of kidney and multifocal necrosis of spleen with splenic infarction. The LD50- 336h of A. veronii 5L was determined at 1.9 × 103.73 CFU/mL. This study revealed the capability of A. veronii as another important pathogen in tilapia culture in Malaysia. [ABSTRACT FROM AUTHOR]

Viral disease outbreak is the most serious issue as it may cause severe losses to farmers as well as to economy in the marine industry worldwide. Among fish viral diseases, betanodavirus is a significant pathogen that causes viral nervous necrosis (VNN) and can result in mass mortalities to fish culture especially at larval stages. In Malaysia, betanodavirus had been isolated from groupers, seabass, red snappers, and golden pomfret. Recently, inconsistent seed supply is observed due to viral infection at larval stages which limits the growth of fish culture. Therefore, seeds of grouper are often imported from neighboring countries such as Indonesia by farmers. Strict importation regulations should be practiced as the importation of fish seeds may become a possible source of the virus entering the country. It is a challenge to track farmers who are affected by the disease in order to segregate or eliminate the VNN carrier spawners. This scenario had resulted in incomplete destruction of diseased fish population and leads to re-occurrence of the disease at the early stage of grouper. This situation warrants immediate attention to develop promising prevention strategies such as a new vaccine which is very important and could work effectively with better farm management approaches. This article discusses the occurrence of viral nervous necrosis (VNN) disease in Malaysia and reviews possible preventive measures via vaccination to combat the disease. [ABSTRACT FROM AUTHOR]