Sushi Fans Warned of Raw Fish Infection Risk

As the popularity of sushi grows, the number of people becoming infected with an illness caused by eating raw meat or fish is on the rise.

A study in the British Medical Journa l says the rise in the number of parasitic infections such as anisakiasis could be linked to eating sushi.

In the study doctors from the Hospital Egas Moniz in Lisbon, Portugal, cite the case of a 32-year-old man who fell ill with severe stomach pain, vomiting and fever for a week before being hospitalized.

Blood tests showed the area below his ribs was tender, and he had an increased number of white blood cells, which typically indicate the body is fighting an infection. It was only when he said he had recently eaten sushi that doctors suspected that he may have anisakiasis, caused when anisakid nematodes (worms) invade the stomach lining or intestines of humans.

Humans become when infected when they ingest raw meat or fish containing worm larvae.

Doctors performed an endoscopy on the man, inserting a small camera into his digestive tract, and found a worm attached to his stomach lining. They removed the larval worm with a special net.

According to the authors of the study, "most of the [anisakiasis] cases were described in Japan due to food habits; however, it has been increasingly recognised in Western countries."

The doctors note that identifying and removing the worms through endoscopy is essential to treatment.

According to the U.S. Center for Disease Control and Prevention the best way to avoid contracting anisakiasis is to "avoid eating raw or undercooked fish or squid."

It recommends either cooking fish or freezing it for at least 15 hours before serving it.

"The treatment for anisakiasis may require removal of the worm from the body by endoscopy or surgery," according to the organization.