There are as many as 6,000 parasites in the body. If you accidentally eat this snail, you may get seriously ill!

The weather has gradually warmed up, and the summer that many people long for is coming. Street food such as barbecue stalls and food stalls that foodies love are becoming increasingly popular. Grilled skewers, grilled squid, and stir-fried snails are all mouth-watering. But wait, don't eat these "snail-flavored delicacies" carelessly, or you may be infected with parasites.

It turns out that many people cannot distinguish between golden apple snails and field snails and eat golden apple snails by mistake. This kind of snail can contain up to 6,000 parasites in its body, which is very harmful to health. So don't eat it carelessly!

The protagonist of this article is the golden apple snail | Tuchong Creative

So, how do you distinguish between golden apple snails and field snails? In addition to snails, what other foods should never be eaten raw? Let's talk about them in detail today.

01

Eating golden apple snails is harmful

Do you remember the Guangzhou roundworm outbreak in Beijing in July 2006? The cause was that diners ate cold-mixed golden apple snails in restaurants and were infected with Guangzhou roundworms. A total of more than 100 patients were involved, and many patients suffered from symptoms such as headaches and convulsions. In August 2006, the Beijing Center for Disease Control and Prevention sampled 97 golden apple snails sold in major seafood markets across the city, and found that 9 of them were parasitic with the first or second stage larvae of Guangzhou roundworms. [1] In recent years, sporadic similar cases have also occurred, and even pregnant women have lost their unborn children as a result.

So where does this snail come from and why is it so harmful?

The golden apple snail, also known as the big bottle snail, snow snail, and apple snail, is native to the Amazon River Basin in South America. Because the golden apple snail is rich in protein, it was introduced to Guangdong, Fujian, Shanghai and other places in my country in 1980 as an aquatic economic organism. Later, it was abandoned because of its poor taste. Because of its strong reproductive ability, an adult female snail lays more than 325,000 eggs per year, which quickly spread to water environments such as rice fields and wild rice fields. [2]

In 2003, the former State Environmental Protection Administration listed the golden apple snail as one of the major dangerous agricultural alien invasive species and included it in the "China's First List of Alien Invasive Species".

The body of the golden apple snail is easily parasitic on the Guangzhou roundworm. There can be more than 6,000 Guangzhou roundworm larvae in a golden apple snail. This parasite can infect humans by eating uncooked golden apple snails.

▲Figure: Reference [3]

The third-stage larvae of Angiostrongylus cantonensis migrate through the central nervous system in the human body and develop into the fourth-stage larvae and the fifth-stage larvae. Because the human body is not a normal host for Angiostrongylus cantonensis, they cannot descend to the pulmonary artery to develop into adults. Instead, they migrate in the nervous system for a long time and induce meningitis. However, they may develop into adults in children. [4]

Infection with Angiostrongylus cantonensis can cause severe headaches, nausea, vomiting, fever, coma, mental disorders and other symptoms, and in severe cases, death. To avoid infection with this parasite, it is recommended to cook the golden apple snails thoroughly or not eat them at all!

02

What is the difference between golden apple snails and river snails?

Many people are not infected with parasites because they eat golden apple snails, but because they mistake them for field snails. Golden apple snails and field snails look similar, but if you look closely, there are still many differences between the two.

① Shell: The shell of young golden apple snails is brittle and breaks easily by pinching; field snails are harder and have thick shells that are not easy to break.

②Color: The shell of the golden apple snail is yellowish brown; the shell of the field snail is bluish brown.

③Shape: The tail of the golden apple snail is short and flat, and the spiral part of the tail is a short cone; the tail of the field snail is long and pointed, and the whole body is conical.

④ Opening: The mouth of the golden apple snail is larger and the lid is flat; the mouth of the field snail is smaller and the lid is round.

⑤Egg color: The eggs of the golden apple snail are pink; the eggs of the field snail are transparent.

▲Figure: References [5]

In addition, it is recommended not to order apple snails out of curiosity, because there is still a risk if the chef does not cook it thoroughly.

03

These 5 foods should not be eaten raw

In addition to the golden apple snail, the following five kinds of food are also "dangerous elements" lurking around people, and we need to be vigilant:

Rice field eel: With its delicious meat, it is known as the "ginseng in water." However, rice field eels are the intermediate host of at least 15 parasites, the most harmful of which is the third-stage larvae of the gnathostome. Many people are infected by eating raw or undercooked rice field eels. The larvae will travel through multiple organs in the human body, invading organs such as the eyes, brain, and spinal cord. [7]

Yellow eel must be cooked before eating | Tuchong Creative

Salmon: Many people like to eat raw salmon, believing that it is a natural and nutritious fish. However, from a safety perspective, it is not recommended to eat it raw. Raw salmon is likely to be contaminated with parasites, mainly Diphyllobothrium latum. When eaten by humans, the larvae enter the human body and develop into adults in the intestines after 3 to 5 weeks. Most infected people have no obvious symptoms, while a few have mild symptoms such as fatigue, weakness, numbness of the limbs, diarrhea or constipation, and hunger, which affect human health. [8]

So is it okay to eat raw salmon with mustard? Not really! Although mustard is rich in isothiocyanates, which can inhibit the growth of microorganisms, it cannot kill the sparganosis in fish muscles.

Crayfish and crab: For those who like to eat drunken shrimp and crab, you need to be alert to lung fluke. Raw and undercooked crayfish and crab may be contaminated with lung fluke. Lung fluke mainly parasitizes the lungs of humans or mammals, and often in the brain, spinal cord, abdominal cavity and subcutaneous tissue, which can damage health.

Water chestnuts are a type of aquatic plant that are easily infected with the worm. When infected with the worm, the amount of stool increases, the stool smells particularly bad, and contains undigested food. A few patients will also excrete some of the worm in their stool or even spit it out of their mouths. They may experience abdominal pain, diarrhea, nausea, vomiting, fever, allergies, and edema. In severe cases, they may also develop intestinal obstruction or even death. Infection in children can also affect their physical and intellectual development. [9]

04

How to avoid parasite infection while enjoying delicious food?

Do not eat raw aquatic plants and meat: such as snails, water chestnuts, lotus roots, drunken shrimps, drunken crabs, salmon, etc. If you want to eat them, make sure they are thoroughly cooked!

Separate raw and cooked food on the cutting board: Sharing the same cutting board for raw and cooked food may lead to cross contamination. It is recommended that you separate raw and cooked food on different cutting boards, or cut vegetables and fruits on the front and raw meat on the back. After cutting raw meat, be sure to thoroughly clean the cutting board and hang it to dry.

Don’t drink raw water: Raw water may contain eggs of certain parasites and bacteria, especially river water, stream water, etc. No matter how clear it is, you must never drink it directly! Even tap water must be boiled before drinking.

Wash your hands frequently: Pay attention to personal hygiene and wash your hands frequently to prevent insect eggs that may be on your hands from attaching to daily necessities and food.

Summarize:

Parasites are very harmful to the human body, so never eat unsafe food raw just for the sake of a taste of so-called "freshness".

Author | Xue Qingxin, member of Chinese Nutrition Society, registered dietitian, registered nutrition technician, health manager, public nutritionist

Review | Chen Shengjun, researcher at the South China Sea Institute, Chinese Academy of Fishery Sciences

Editor | Ding Zong

References:

[1] He Zhanying, Jia Lei, Huang Fang, et al. Investigation of an outbreak of Angiostrongylus cantonensis in Beijing[J]. Chinese Journal of Public Health, 2007, 23(10):1241-1242. DOI:10.3321/j.issn:1001-0580.2007.10.049.

[2] Wang Chanjuan, Song Zengfu, Lu Xian, Wang Ling, Luo Nan, Yao Linong, Zhang Yinjiang. Current status and prevention and control of golden apple snail invasion in my country[J]. Journal of Biosafety, 2021, 30(03): 178-182.

[3] Wang Fei, Cao Shuzhen, Zhang Xiaoxiao, et al. Research status of growth, development and morphological characteristics of Angiostrongylus cantonensis[J]. International Journal of Medical Parasitology, 2013, 40(4): 225-230. DOI: 10.3760/cma.j.issn.1673-4122.2013.04.011.

[4] WS321—2010 Diagnostic criteria for Angiostrongylus cantonensis

[5] Ren He, Gao Hongjuan, Xue Juan, Gong Ning, Chen Xiang. Biological characteristics and control of golden apple snails[J]. Bulletin of Biology, 2020, 55(12): 1-3.

[6] Yang Yuexin. Chinese Food Composition Table 6th Edition Volume 2[M]. Peking University Medical Press, 2018

[7] Cai Wuwei, Lin Chenxin, Xie Hanguo, Jiang Dianwei. Investigation on the distribution of stage III larvae of Gnatostoma albus in the eel[J]. Strait Journal of Preventive Medicine, 2020, 26(02):10-11+42.

[8] Li Yanrong, Li Lisha, Jiang Dianwei, Chen Zhuyun. A case report of Diphyllobothrium latum infection after eating raw salmon[J]. Chinese Journal of Parasitology and Parasitic Diseases, 2013, 31(06):494.

[9] Zhou Qing, Peng Qingqing, Qiu Jinbo, et al. Research progress in diagnosis and prevention of ginger fasciatus disease[J]. Chinese and Foreign Health Digest, 2014, (23): 108-109.