Because sushi is not cooked, the larvae can in turn transfer into the flesh of any human that eats the fish.
Once a human is infected, a tapeworm will grow inside the intestine to a length of up to 15metres over a period of weeks. It can survive for years and go undetected for weeks or months, in turn releasing its own eggs that infect other parts of the human body.
Symptoms include fatigue, constipation and abdominal discomfort – which can be so mild the victim may not notice anything is wrong.
If larvae begin to migrate to other parts of the body they can start to eat away at the liver, eyes, heart or brain and cause life-threatening conditions.