There are some fish diseases and infections that can be transmitted from fish, and the water in which they are cultured, to humans. Although the infection of humans with fish pathogens is a relatively unusual event, it is a health risk that needs to be recognised by fish farmers and other people who handle and/or consume farmed seafood.
The incidence of transmission of disease from fish to humans is dependant upon several factors including the type of organism (viral, parasitic or bacterial), the susceptibility of the host (immuno-compromised individuals, presence of open wounds) and environmental factors (quality of the water, depth of penetration of fish spines).
Most disease causing agents which can transmit from fish to humans are bacterial and their clinical effects and treatments are listed in Table 1.
Optimum farm design, appropriate husbandry and handling, water quality management and regular fish health monitoring will reduce the risk of disease transfer from fish and their environs to workers in the aquaculture industry.
Table 1. Some common bacteria and their clinical effects following infection in humans. Some species have been recorded in Australian fishes. Clostridium botulinum is also found occasionally in the intestinal tract of fish.
Serious infection uncommon
Soft tissue infections; arthritis; septicaemia; gastroenteritis; meningitis; osteomyelitis
Skin infection (on hands), septicaemia, endocarditis (rare); lymphangitis
Antibiotics; most strains resistant to Vancomycin
Suppurating ulcers; cellulitis;
Lesions; gastroenteritis; septicaemia
Skin lesions (usually hands); ulceration and inflammation of joints
Septicaemia; abdominal pain; diarrhoea; nausea; vomiting
Non-bacterial disease-causing agents include:
Several parasites can infect humans as non-traditional hosts. They enter humans by ingestion of raw or undercooked infected fish. Trematodes and nematodes are known to cause infection in humans. Harmful algae (dinoflagellates and diatoms) may also accumulate in shellfish and can cause illness in humans. Clinical signs can include muscular aches, gastrointestinal and neurological disorders.
Shellfish, such as oysters, mussels and clams can bio-accumulate viral pathogens from polluted waters. The consumption of contaminated shellfish can cause gastroenteritis, respiratory illness, fever and hepatitis. Commercial shellfish are grown under a strict food safety program administered by the NSW Food Authority.
Cellulitis– inflammation of cellular tissue.
Endocarditis– inflammation of the membranes which line the heart and heart valves.
Lymphadenitis– chronic swelling of lymph nodes
Meningitis– inflammation of the brain and spinal chord membranes.
Osteomyelitis– inflammation of the bone
Septicaemia– bacterial infection of the blood
Suppurating- discharging pus from a wound.
Lehane L and Rawlin GT (2000). Topically acquired zoonoses from fish: a review. Medical Journal of Australia 173(5):256-9.
Durborow RM (1999). Health and safety concerns in fisheries and aquaculture. Occupational Medicine 14(2):373-406.
DPI – Fish Health Unit, Elizabeth Macarthur Agricultural Institute
Telephone 02 4640 6333
NSW Department of Health
Telephone 02 9391 9000
NSW Food Authority
Telephone 1300 552 406