A bite of sashimi, you can eat a few parasites

The fresh sashimi you eat may be a Class I carcinogen

Eating sashimi has become a trend.

In the gourmet documentary “The Taste of Laoguang”, fresh grass carp that has just been salvaged is sliced ​​into 0.5mm-thick fish fillets under the hands of a chef with superb knives, crystal clear. Mix with condiments such as sesame oil, soy sauce, peanut oil, etc. This is “Shunde Yusheng”.

In many cities in China, Japanese food shops selling sashimi and sushi are becoming more and more common.

But many people don’t know that delicious sashimi may be a “wormhole”.

Food writer Chua Lam once encountered: “The conveyor belt sushi restaurant in Hong Kong bought (bonito) and cut it as sashimi… As soon as it was opened, small yellow tumors grew in the abdominal wall. The bread is full of larvae.”

Eating sashimi is like opening a blind box. You never know if there is a creeping parasite in the next delicious bite .


A bite of fresh sashimi, a few parasites

“Sashimi is slaughtered and killed, absolutely fresh, absolutely assured.”

If you see a restaurant with such a slogan, don’t enter! Fresh sashimi that has not undergone any treatment is likely to be the “home” of parasites.

There are many types of parasites infecting fish, but only a few parasites can cause illness.

“Clonorchis sinensis”, also known as “liver fluke”, is the most common pathogenic parasite in freshwater fish in China. After eating sashimi infected by liver flukes, the worms are mainly parasitic in the bile duct and gallbladder of the human body, causing a series of bile duct diseases, such as cholangitis, cholecystitis, gallstones, etc. [1].

A bite of sashimi, you can eat a few parasites

A patient who was infected with paragonimiasis after eating sashimi. The arrow in the radiograph refers to the lesion caused by paragonimiasis

Adults of Clonorchis sinensis can live in the bile duct for up to 20-25 years [2]. When there are too many worms, the dead worms, eggs and mucins will block the bile ducts for a long time, which can also cause biliary cirrhosis and bacterial infections [1] [2].

Studies have shown that the risk of cholangiocarcinoma in people infected with Clonorchis sinensis is 4.5 to 6.1 times that of non-infected people [3].

Therefore, what you eat is fresh sashimi, which may also be the famous class I carcinogen of cholangiocarcinoma [4].

The widespread distribution of this parasite in freshwater fish may be beyond your imagination. There are 139 kinds of freshwater fish in China, Japan and South Korea. Even common domestic fish species, such as carp, silver carp, clear carp (grass carp), crucian carp, etc., cannot be avoided [1].

In 2010, sampling results of 35 fish ponds across Guangdong showed that nearly 70% of the fish ponds were infected with Clonorchis sinensis. Shunde most people like to use to make grass carp sashimi (ie grass), the detection rate of Clonorchis sinensis was 47.31% [5].

A bite of sashimi, you can eat a few parasites

Shunde Yusheng under the lens of the gourmet documentary “The Taste of Laoguang”. Most of the fish in this place is made from fresh grass carp

According to this detection rate, every time you eat two untreated sashimi of grass carp, you may have a face-to-face encounter with the liver fluke.

In provinces and cities that have the habit of eating sashimi, the infection rate of Clonorchis sinensis is very high.

In 2015, the survey of the current status of human parasitic diseases in 35 provinces across the country showed that the infection rate in Guangdong and Guangxi was significantly higher than that in other provinces. The infection rate of Clonorchis sinensis was 6.68% in Guangxi and 1.91% in Guangdong [6].

what is this concept?

According to a rough estimate of the number of permanent residents in the two provinces at that time, the scale of clonorchiasis infection in Guangxi and Guangxi was about 5.276 million people[6-8].

Some people would say, “Freshwater fish have many parasites and are not suitable for raw consumption. In contrast, marine fish are safer than freshwater fish. Marine fish have fewer parasites, and because of the osmotic pressure and the high salt environment of seawater, parasites cannot be found Survive.”

This is only half right.

A bite of sashimi, you can eat a few parasites

Brother up at station B tried to eat the American snail overturned and ran into a parasite. American snails are produced in the deep sea

Marine fish are indeed safer than freshwater fish, and there are indeed fewer parasite species (focus, species) of marine fish than freshwater fish as a whole. However, the infection rate of parasites in freshwater fish and marine fish is similar [9].

The parasites of some marine fish are also pathogenic.

Take Anisakis, the most common parasite in seafood sashimi, the human body really cannot provide the most suitable living environment.

Most of the anisakis worms eaten in the stomach are larvae, they do not grow up, but they do not die. They eat and drink in your body, and sometimes travel in groups, which is medically called “visceral larval migration.” After their death, the corpse is buried in the stomach wall to form a swelling, which sometimes causes severe allergic reactions [10].

Eating this parasite can cause severe abdominal pain and vomiting in severe cases. There is no specific medicine for Anisakis worms that swim into the gastrointestinal tract. Once infected, they can only be removed by gastroscopy [11].

A bite of sashimi, you can eat a few parasites

What does anisakis look like? I won’t put its disgusting real shots here. In Chapter 4 of “Working Cell”, there is a scene of Anisakis burrowing in the stomach wall.

Just thinking about it, my stomach is already hurting.

And this parasite is also very widespread in marine fish.

An investigation into the infection of Anisakis in fishes in Zhoushan fishing grounds in Zhejiang Province showed that of 29 species of 444 marine fish, 218 of the larvae of Anisakis were detected. The total infection rate of marine fish is 49.1% [12].

One of the 38cm long mackerel carried 114 Anisakis larvae [12].

Therefore, if you eat freshly slaughtered sashimi that has not undergone any treatment, you are likely to have the opportunity to taste the same fresh and original parasites. Isn’t it exciting?


How to eat sashimi to minimize the risk

So the question is, is there any solution to the safety of sashimi eating?

Take Japan as an example. Japan, which loves sashimi and sushi, has suffered from parasitic diseases in the past. But because of this, Japan has accumulated a lot of experience in eating sashimi. In recent years, the scale of parasite infection in Japan has not been so serious.

In 2020, according to the latest data released by the Ministry of Health, Labour and Welfare, there are 386 foodborne diseases caused by parasites in Japan, with 484 patients. Among them, only 396 patients were caused by Anisakis, the most frequently encountered raw seafood [13].

After the fresh fish is caught and slaughtered, after a certain amount of treatment, many risks of parasites can be avoided.

First of all, the types and numbers of parasites carried by sashimi fish are also different in different origins and species. Freshwater fish and some marine fish species with high infection rates can basically be excluded.

For example, the “salmon sashimi” commonly found in authentic Japanese food stores is mostly artificially farmed Atlantic salmon imported from Norway.

The breeding conditions for this Atlantic salmon are extremely strict. The parental spawning and fry cultivation are first completed in the land-based breeding workshop, and then transferred to the sea by live fish boats, where deep-water cages are used for breeding. Each batch of fish eggs has a complete production file record. The aquaculture water is disinfected and then flows into the aquaculture pond. The feed is heated and treated without parasites [14].

The Norwegian Atlantic salmon, which is rigorously bred in this way, has a very low risk of infecting parasites directly from raw food.

A large-scale sampling involving 37 salmon farms in Norway found that none of the 3,525 farmed Atlantic salmon found any parasites. Only in the stomachs of 3 immature Atlantic salmon were found 2 Anisakis and several adult parasites that do not cause harm to the human body [15].

The fish species, origin, and breeding methods are reliable, and the probability of eating parasites will be much lower.

But this is not enough. To reduce the risk of infecting parasites by eating sashimi, the FDA provides a necessary way-freezing that meets certain conditions.

Option 1: Freeze and store for 7 days in an ambient temperature of -20°C and below;

Option 2: Freeze and store for 15 hours in an ambient temperature of -35°C and below;

Solution 3: Freeze in an ambient temperature of -35°C and below, and store at an ambient temperature of -20°C and below for 24 hours;

The above 3 options may not be suitable for freezing very large fish (for example, thicker than 6 inches)

Regarding the insecticidal effect of freezing, it is called “sufficient to kill parasites (sufficient to kill parasites)” in the FDA’s food safety regulations [16].

There are also standards for Chinese sashimi.

In the “National Food Safety Standard Animal Aquatic Products” document issued in 2015, it is clearly stipulated that “ready-to-eat raw animal aquatic products” need to be “not detectable parasites such as fluke metacercaria, nematode larvae, and tapeworms.”[ 17].

Generally speaking, formal production companies will implement this standard, and the products will be listed first and then subject to random inspection. Not only that, pathogenic bacteria and heavy metals are all within the scope of detection, and all links of catering circulation are also subject to supervision and spot checks and risk monitoring, so as to reduce food safety risks as much as possible.

Most of the seafood purchased through formal channels and tested is safe.

Of course, the “regular channels” must have fixed booths and business licenses at the very least, and small mobile vendors are a fish that misses the net through random inspections.

Through a series of strict controls on breeding, variety, cold chain transportation, storage environment, and sampling, 99-point safe sashimi does exist.

As for the remaining 1 point, it depends on experience and luck.


If you want to be 100% safe, I advise you not to eat

For consumers, no one can guarantee that the 1% probability of “winning a lottery” will not fall on them. The whole process of making sashimi is a black box, and there are too many uncontrollable factors.

For example, freezing is the most critical step in killing parasites. Once the temperature conditions and the required length of time are not reached, the risk of infection with parasites will not be low.

In 2019, a paper published in the journal Parasitology Research found that the larvae of Anisakis in the herring did not completely die if they were not frozen in accordance with the requirements of the FDA and the European Union. After freezing for 24 hours, take out the sample and observe it under a microscope, and you can see the larvae moving [18].

Consumers have no way of knowing whether the store strictly implements freezing standards in Japanese food stores and fish sashimi stores. On the e-commerce platform, many merchants will pack and deliver them immediately after slaughter. The delivery temperature is -4°C, and the recommended storage temperature is -18°C.

In addition to freezing, there may also be problems with the fish species served in restaurants.

“Salmon sashimi” made from rainbow trout was once popular in Chinese restaurants. But this kind of “salmon sashimi” parasite infection risk is very high.

Rainbow trout and Atlantic salmon are both called “salmon”, but they are actually not the same thing at all. The former are freshwater fish, which are exposed to many types of parasites, but the breeding methods and deworming treatments may not be able to meet the “raw salmon” standard. Just because the color and texture of the meat resemble that of Atlantic salmon, some sellers claim that they sell “freshwater salmon” and the price is not cheap.

For ordinary consumers who are not so knowledgeable, buying expensive is indeed lower risk than cheap. But fear, you bought rainbow trout at the price of Atlantic salmon.

In 2018, surging investigative news digs deep into the domestic “salmon” market. The more than 9,000 tons of “salmon” that China consumes each year does not come from the distant deep sea, but a reservoir in the Yellow River. With an annual output of 40,000 tons of rainbow trout, less than one-third of rainbow trout meet the qualified raw food standard [19].

Take a step back, there are no parasites in the seafood you eat, but there are too many uncontrollable risks from raw food.

It may be contaminated during handling, processing or preparation. Is it stored and transported at the proper temperature? Is there any cross-contamination caused by contact with other contaminated seafood or seawater? Does it carry hepatitis A virus, Salmonella, and Vibrio vulnificus[10]?

In fact, in Japan’s annual food poisoning incidents, bacterial and viral infections are far more serious and more common than parasitic infections [13].

The way to stay away from all the above hazards and achieve 100% safety is actually very simple, heating.

Sprinkle some pepper and sea salt, or a few drops of soy sauce, whether it is frying or steaming, is it not fragrant?

Of course, if you really can’t resist the deliciousness of sashimi and are willing to try it even if you are at risk, then keep these points in mind before eating:

  • Do not eat offal, do not eat freshwater sashimi and snails (even if it is frozen, it may contain liver flukes), do not eat freshly slaughtered, unfrozen sashimi.
  • When eating sashimi, keep your eyes wide open and check if there are any visible parasites; if so, put it down immediately and do not eat it again. Even if the adults are removed, they may still contain larvae and metacercariae.
  • It is very important to eat sashimi at a trusted restaurant with complete qualifications, good environment! Keep an eye out for sashimi that is extremely low-priced, poorly presented, and smelly, and don’t try it lightly.
  • If you are buying sashimi online, choose SF Express as much as possible to prevent deterioration. Don’t eat it immediately after you get the product, first freeze it in accordance with the FDA’s freezing requirements.
  • If you are a serious fan of sashimi and eat sashimi frequently every month, then remember to go to the hospital regularly to check for parasitic infections.
  • Finally, if you are a susceptible population (the elderly, young children, pregnant women, and people with weakened immune systems), it is strongly recommended not to take the risk.

The scientificity of this article has been reviewed by Zhao Kun, an inspection engineer of the National Food Quality Supervision and Inspection Center (Shanghai)


[1] Liu Mingyuan, Liu whole, Fang Huan, YIN Ji-gang, Wang Xuelin, Li Jianhua, … & Wu Xiuping. (2014). Our food-borne parasitic diseases and related research progress. Chinese Journal of Veterinary Science, 34 (7 ), 1205-1224.

[2] Wang Caiqin, Yu Xinbing, & Li Xuerong. (2015). Research progress on the relationship between clonorchis sinensis infection and the occurrence and development of cholangiocarcinoma. Chinese Journal of Parasitology and Parasitic Diseases, 33(2), 142-146.

[3] Tang Lei, Ge Tao, Yin Shi Hui Yuan cool, & Xing Zhifeng. (2018). Investigation of Clonorchis sinensis infection in the patient population in Sanjiang Plain. Disease Surveillance, 33 (6), 525-527.

[4] American Cancer Society. (2021).Known and Probable Human Carcinogens.

[5] Zhang Xianchang, Pei Fuquan, Zhang Qiming, Lin Rongxing, Huang Shaoyu, Wang Jinlong, … & Chao Bin. (2010). Analysis of freshwater aquaculture environmental sanitation and Clonorchis sinensis intermediate host infection in some areas of Guangdong Province. South China Preventive Medicine , 36(3), 9-13.

[6] Chen Yingdan, Zhou Changhai, Zhu Huihui, Huang Jilei, Duan Lei, Zhu Tingjun, … & Zhou Xiaonong. (2020). Survey and analysis of the status of key human parasitic diseases in 2015. Chinese Journal of Parasitology and Parasitic Diseases , 38(1), 5.

[7] Guangdong Bureau of Statistics. (2020). Guangdong Statistical Yearbook.

[8] Guangxi Statistics. (2020). Guangxi Statistical Yearbook.

[9] Poulin, R. (2016). Greater diversification of freshwater than marine parasites of fish. International Journal for Parasitology, 46(4), 275-279.

[10] Bari, M. L., & Yamazaki, K. (Eds.). (2018). Seafood Safety and Quality. CRC Press.

[11] Zhan Meixi. (2001). Human Parasitology (Fifth Edition).

[12] Zhang Junhe, Lin Qi, Zhang Gantong, He Weixian, Li Kefeng, & Xu Xu. (2010). The current status of Anisakis infection and its physical and chemical tolerance in Zhoushan fishing grounds. Chinese Journal of Preventive Medicine, 44(11 ), 1037-1042.

[13] Ministry of Health, Labour and Welfare of Japan. (2020). Food poisoning statistics.

[14] Zhang Yulei, Ni Qi, Liu Huang, & Zhang Chenglin. (2020). Status of industrial farming of Atlantic salmon in Norway and its enlightenment to China. Transactions of the Chinese Society of Agricultural Engineering, 36(8).

[15] Levsen, A., & Maage, A. (2016). Absence of parasitic nematodes in farmed, harvest quality Atlantic salmon (Salmo salar) in Norway–Results from a large scale survey. Food Control, 68, 25-29.

[16] FDA.(2021).Fish and Fishery Products Hazards and Controls Guidance.

[17] National Health and Family Planning Commission. (2015). National Standard for Product Safety Animal Aquatic Products.

[18] Podolska, M., Pawlikowski, B., Nadolna-Ałtyn, K., Pawlak, J., Komar-Szymczak, K., & Szostakowska, B. (2019). How effective is freezing at killing Anisakis simplex, Pseudoterranova krabbei, and P. decipiens larvae? An experimental evaluation of time-temperature conditions. Parasitology research, 118(7), 2139-2147.

[19] The Paper. (2018). Investigation: Rainbow trout is classified as salmon. What is the distance between the standard and reality.

Posted by:CoinYuppie,Reprinted with attribution to:https://coinyuppie.com/a-bite-of-sashimi-you-can-eat-a-few-parasites/
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