Zoonotic diseases of fish and their prevention and control.

Fish and aquatic-derived zoonotic diseases have caused considerable problems in the aquaculture industry and fishery worldwide. In particular, zoonotic diseases can pose widespread threats to humans. With the world's growing population and potential global trade of aquaculture and fish, the risk of environmental contamination and development of fish and aquatic-derived zoonoses in humans are increasing. The important causes of zoonoses include bacteria, parasites, viruses, and fungi. The zoonotic bacterial agents are divided into two main groups: Gram-positive (Mycobacteriaceae, Streptococcaceae, Erysipelothricaceae families) and Gram-negative (Aeromonadaceae, Vibrionaceae, Pseudomondaceae, Enterobacteriaceae, and Hafniaceae families). The premier parasitic agents include cestodes (tapeworm; e.g. Diphyllobothrium spp.), trematodes (fluke; e.g. Opisthorchis spp.), and nematodes (round worm; e.g. Anisakis spp.). In addition, protozoan organisms such as Cryptosporidium spp. are also considered fish-derived zoonotic pathogens. Two groups of fish-associated fungi causing basidiobolomycosis and sporotrichosis also pose a zoonotic risk for humans. The majority of the fish-derived zoonotic diseases are transmitted to humans mainly via the consumption of improperly cooked or raw fish or fish products. Therefore, the incidence of zoonotic diseases can be reduced by properly processing fish and fish products, e.g. by thermal (heat/freezing) treatment. The prevalence of zoonotic agents in fishes varies seasonally and should be regularly monitored to evaluate the prevalence of pathogens in both wild and cultured fish populations. This review focuses on the fish zoonotic agents/diseases and their control and prevention.

Development and evaluation of colloidal gold immunochromatography test strip for rapid diagnosis of nervous necrosis virus in golden grey mullet (Chelon aurata).

A lateral flow immunochromatography strip test, based on antibody-gold nanoparticles specific for nervous necrosis virus (NNV), was developed for rapid, on-site detection of the virus in fish stocks. A monoclonal antibody against NNV was conjugated with colloidal gold as the detector antibody. A rabbit anti-NNV polyclonal antibody and goat anti-mouse IgG antibody were blotted onto the nitrocellulose membrane as the capture antibodies on the test line and control line, respectively. The reaction could be seen by the eye within 15 min and did not cross-react with the other viruses tested. The detection limit of the strip was approximately 103 TCID50 /ml and had good stability after storage at 4°C for 8 months. When brains of 70 naturally infected golden grey mullet, Chelon aurata, were tested with the strip test, the diagnostic specificity and sensitivity of the test compared to real-time RT-PCR were 100% and 74%, respectively. Therefore, the one-step test strip developed here had high specificity, reproducibility, and stability. This, together with its simplicity to use and rapid detection, without the requirement of sophisticated equipment or specialized skills, makes the strip suitable for pond-side detection of NNV in farmed fish.