The Japanese delicacy sushi is something which people all over the world relish. In the United States, its popularity has grown by leaps and bounds with several Japanese restaurants mushrooming across the country.

However, people need to be cautious while consuming the delicacy as a particularly dangerous parasite may contaminate the raw fish in the sushi. A new study indicates that consuming parasite-ridden raw fish or seafood can cause anisakiasis.

What Is Anisakiasis?

According to the Centers for Disease Control and Prevention, anisakiasis is a parasitic disease the anisakid nematodes (worms) — that can invade the stomach wall or intestines of humans — cause. The transmission of this disease occurs when infectious larvae are ingested from fish or squid, which humans eat raw (or they are undercooked).

The symptoms and signs of anisakiasis are nausea, abdominal pain, abdominal distention, vomiting, diarrhea, blood and mucus in stool, and mild fever. Allergic reactions with rash and itching, as well as trouble breathing can also occur.

Detection And Treatment

According to Joana Carmo, the study's lead author and a physician in the department of gastroenterology at the Egas Moniz Hospital in Portugal, a recent case involving a 32-year-old man suffering from the disease has brought the problem to the fore.

The man complained of severe pain in his stomach along with vomiting and fever. Doctors performed blood tests which revealed he had high presence of white blood cells, which is an indication of infection. It was only after the patient shared that he consumed sushi a few days before developing the symptoms, that physicians suspected a parasite infection. So, they performed an endoscopy.

Endoscopy is a gastrointestinal test where a tube equipped with a small light and camera is orally inserted down a person's throat, into their stomach.

The test revealed a parasite attached to a swollen intestinal membrane. Using a special net known as the Roth, doctors were able to remove the worm from the patient's stomach. Tests revealed that it was a member of the Anisakis nematode species, which is responsible for anisakiasis.

After the removal of the parasite, the patient's symptoms also disappeared in a matter of days.

How Widespread Is The Disease?

Japan and some European countries like Spain are the worst affected. Latest estimates indicate nearly 2,000 to 3,000 cases of anisakiasis occur in Japan each year due to the practice of consumption of uncooked or improperly cooked seafood and fish.

In Spain, the use of raw and marinated anchovies may be responsible for anisakiasis and latest estimates suggest 8,000 annual cases of the disease.

The CDC recommends avoiding the consumption of raw fish or seafood. Cooking the fish at a temperature over 145 degrees Fahrenheit or storing the raw fish at temperatures below -4 degrees Fahrenheit for at least 72 hours kills the parasite.

The results of the new study have been published in the journal BMJ Case Reports.

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