The growing popularity of sushi could fuel a rise in deadly parasitic worm infections, doctors have warned.

Raw fish can carry tiny worms that bury into the human gut if eaten, a condition known as anisakiasis, which can cause severe stomach pain, vomiting and fever.

However, in severe cases it can cause an anaphylactic reaction, with the parasites triggering an erratic heartbeat and respiratory failure, which can be fatal.

Until recently, cases in Western countries were rare because most dietary fish is cooked, which kills the worms. But the rise of sushi has led to cases in hospitals across Europe.

In the latest incident a 32-year-old Portuguese man was left in agony for a week after eating slices of raw fish from a Japanese restaurant.

When doctors put an endoscope - a long tube with a camera - down his throat they found a mass of writhing white larvae burrowing into his gut lining. After the worms were cleared out using a special kind of retrieval net, the man’s symptoms quickly cleared up.