According to the Centers for Disease Control and Prevention (CDC), Anisakiasis is a disease caused by the “Anisakids nematodes,” which are worms that invade the stomach wall or the intestines. Sadly, these parasites are common to be found in raw foods, such as sushi.

Sushi lovers have grown in numbers all over the world. However, they need to be cautious when eating this Japanese delicacy, if they don’t want to have parasites in their bodies that can harm them. The issue has gained a lot of attention soon after a 32-year-old man got the disease after he ate sushi.

Image credit: Duolingo
Image credit: Duolingo

“There is a need to better estimate and understand the burden of disease worldwide (especially in those countries where consumption of raw or undercooked fish is common),” said Miguel Bao, a doctoral candidate in systems biology at the University of Aberdeen.

A few decades ago, doctors didn’t know about Anisakiasis disease

Anisakiasis is a recently discovered disease caused by eating parasite-contaminated fish or seafood, which is worrisome as in western countries the popularity of sushi and other raw food has gained a lot of popularity. According to Dr. Joana Carmo, lead author and a physician in the gastroenterology department of the Hospital of Egas Moniz in Lisbon, Portugal, doctors didn’t know about this disease a few decades ago.

She said Anisakiasis was described for the first time during the 60’s in The Netherlands after a patient reported having consumed some lightly salted herring. Therefore, it was first referred to as “herring worm disease.”

Ever since, more cases have been reported in different countries, especially in Japan because of the greater amount of raw fish ingestion.

What are the consequences of Anisakiasis?

The most common symptoms of the infection are nausea, abdominal pain, vomiting, diarrhea, mild fever and blood and mucus in stool. The affected people can also show signs of rash and problems to breath. Some might lose consciousness. According to Bao, the allergic response can be life-threatening.

“Some people experience a tingling sensation after or while eating raw or undercooked fish or squid. This is actually the worm moving in the mouth or throat,” reads the CDC website.

The study authors described the illness using the case of a 32-year old Portuguese man. He was healthy, but he started feeling sick. He complained of severe upper gut pain, and also vomited and had a fever. He didn’t go to the hospital until a week after the symptoms started. Carmo and her co-authors said that there was tenderness in the abdomen of the patient. Blood studies showed the number of white blood cells had increased, which is typical when there are worms in the organism. The patient said that he had recently eaten sushi.

Anisakiasis parasite. Image credit:
Anisakiasis parasite. Image credit:

Based on that, the patient went through upper gastrointestinal endoscopy, which is a non-surgical examination of the digestive tract. Doctors perform it with a flexible tube and take a picture of the organism with a little camera that the tube has at its end.

The medical procedure showed that there was a parasite attached to the intestines penetrating the stomach of the man. The worm was removed with a special net, named Roth net. It is a plastic net that doctors use to remove polyps from the colon and other things such as worms and parasites.

The worm was analyzed to confirm that it was the Anisakids nematodes. The patient was recovered within a few days.

The study was published in BMJ Case Reports last Thursday.

Cases of Anisakiasis are most common in Japan and Spain

About 2000 to 3000 cases of anisakiasis are reported in Japan each year, due to the consumption of raw or uncooked dishes such as sushi. Japan is one of the places with the highest rates of anisakiasis diagnoses, alongside other European countries. This is particularly concerning in Spain, where there are about 8000 infections each year for the ingestion of marinated anchovies and raw food.

“In European countries, fish infestation is probably more frequent than we thought. One study showed that anisakids simplex (the species most commonly associated with human infections) was found in 39.4% of the fresh mackerel examined from different fish markets in Granada, Spain” said Dr. Carmo.

However, according to another study made in Spain, about 56 percent of blue whiting fish had the worm that causes anisakiasis. The fish was analyzed in five different market chains.

Though Europe and Japan are the most affected, it doesn’t mean that the disease is not found in other places such as South America and the United States. Bao said that anisakiasis is usually underdiagnosed and underestimated by scholars.

The CDC recommends people to avoid the consumption of raw fish. It must be cooked at a temperature over 145 degrees Fahrenheit. If not, people should store it at -4 degrees Fahrenheit for three days to kill parasites.

Source: Tech Times