Truth: This horrible sparganosis is indeed a dangerous parasite, but you don't have to refuse delicious bullfrogs because of it. As long as you pay attention to cooking methods, you can still eat them with confidence.
Life history of sparganosis Strictly speaking, sparganosis is not the name of a parasite. It is a general term for the larvae of some species of tapeworms in a developmental stage, which is called "metaphase tapeworm stage". Although it is not fully developed, it is very similar to adults in appearance, and because of its strong fluidity, sparganium often brings more harm to parasitic hosts than its adults.
Judging from the symptoms and etiology described in Weibo, it is very likely that Liu Fang was infected with the common sparganosis mansoni. Scottish doctor patrick manson first discovered Schizothorax mansoni when he was dissecting in Xiamen, China, hence the name.
The adult sparganium mansoni is called sparganium mansoni of Diptera, which belongs to the same class as the well-known pork tapeworm. Like many other kinds of parasites, Taenia mansoni needs to move in multiple hosts during its lifetime. The ultimate hosts of Taenia mansoni are mainly cats and dogs, and sometimes there are carnivores such as tigers and leopards. In the intestines of these animals, Taenia solium adults can be parasitic for several years and produce a large number of eggs. These eggs enter the natural water system with feces and then hatch into larvae. In water, larvae are eaten by plankton called cyclops (the first intermediate host) as food, and then enter tadpoles (the second intermediate host) along the natural food chain. As tadpoles develop into frogs, the larvae also develop into "tapeworm metaphase", at which time the larvae are what we call sparganosis. Finally, when infected frogs are swallowed by animals such as cats and dogs, sparganosis reaches their ultimate hosts. There they will develop into adults of Taenia solium and lay eggs. In addition to the final host, sparganosis will enter other predators, such as snakes, with frogs. In these animals, sparganium can survive and maintain the ability to infect other organisms, but it cannot develop into adults.
The life history of Taenia solium tells us that improper consumption of frogs and snakes, such as direct consumption of untreated frogs or snake tissues-drinking snake blood, swallowing snake gall, eating cold snake skin, or drinking water contaminated by cyclops by mistake, may cause Taenia solium infection. In addition, because frog meat is considered to have the effect of "cooling and detoxifying", some people will apply raw frog meat to wounds or skin abscesses. This behavior without scientific basis provides great convenience for sparganosis to enter the human body through the skin. In China, more than half of the people infected with sparganosis were infected by eating raw frog meat. In addition, some people have a "strange" eating habit of swallowing tadpoles raw, which is also easy to cause infection.
It is not a suitable host for taeniasis or sparganosis, but it is very harmful to human body. In particular, sparganosis can spread between different parts of the human body, which may lead to systemic damage. The diseases caused by sparganosis are collectively called sparganosis, which can be roughly divided into five categories according to the location of the disease: eye, subcutaneous, oral and facial, brain and internal organs. In China, the incidence of ocular sparganosis is the highest, and the symptoms are quite horrible. The patient's eyes will have lumps, accompanied by all kinds of serious discomfort. If sparganium invades the eyeball, it may even lead to blindness. Sometimes, sparganium will "crawl" out of the affected area, and the plot of "a bug crawling out of its eye" in many heavy stories probably stems from this symptom. However, Liu Fang suffers from cerebral sparganosis relatively rarely. The symptoms of these diseases are quite similar to brain tumors, so they are often misdiagnosed as brain tumors. The harm of cerebral sparganosis is also terrible, and the most serious one will lead to paralysis.
At present, the main method to treat sparganosis is to remove parasites by surgery. Although the treatment itself is painful and risky, even if the parasite is removed, the human body may continue to suffer. For example, Liu Fang suffers from epilepsy, which is an example.
Eat frog three axes safely
Sparganosis is extremely harmful and difficult to cure, so how to prevent it becomes the key.
For most urban people who have normal eating habits and use safe tap water system, it is unlikely that they will have high-risk behaviors such as swallowing tadpoles and eating frog meat raw, and they are unlikely to be infected by polluted water sources, so the focus of prevention is diet.
Shut your mouth and give up your hobby of wild frogs and snakes.
Because the probability of these two wild animals carrying sparganosis is very high. Take the survey results in Hangzhou and its surrounding areas as an example. Up to 60% of wild frogs and snakes carry sparganum. In Shanghai, researchers found nearly 150 sparganium from a wild king snake. Such a high parasitic rate and quantity will naturally lead to a sharp increase in the risk of illness. In addition, wild frogs and snakes are important links in the natural ecosystem. Giving up eating them not only reduces the possibility of getting sick, but also protects the natural environment. Why not?
After scientific treatment, the food sparganium can tolerate the temperature change from MINUS 10℃ to 56℃ in the natural environment. At zero degree, the so-called cold storage condition, sparganium can survive in the muscle tissue of the host for decades. Schizothorax is relatively sensitive to high temperature. Under the condition of in vitro culture, Schizothorax basically lasts for 5 minutes at 56℃.
However, some research results show that sparganium parasitized in food is not so sensitive to high temperature. Someone put a small piece of frog meat (about 1 cm square) containing sparganum in an environment of 56℃. After 3 hours, the infectious sparganium still remained in frog meat. It can be seen that the truly safe treatment method is to thoroughly cook the ingredients at a higher temperature. Cooking, chafing and other methods often can't completely cook some parts of the ingredients, and it may become a safety hazard because it can't completely kill sparganium.
In addition to heating, freezing is also one of the ways to kill sparganum. Studies have shown that freezing at -20℃ for 2 hours can kill all the sparganium in frog meat. Of course, the effect of freezing method is not only related to temperature and time, but also related to the size of the material. It is safer to freeze frog meat or snake meat in large packages at -20℃ for 24 hours.
Don't pin your hopes on any spices.
People often use soy sauce, vinegar and ginger juice when processing food. It should be said that these spices are indeed lethal to sparganosis and can also reduce sparganosis infection. However, according to the research data, ginger juice does not have the ability to completely kill sparganum. Soy sauce and vinegar can completely kill sparganium, but the operating condition is that the snack is soaked in vinegar for at least 24 hours or soy sauce for at least 6 hours. In practice, we are unlikely to cut the ingredients too small, and we are unlikely to leave the ingredients in the seasoning for so long. Therefore, it is not a reliable method to kill insects simply by pickling with spices.
Many people like to drink while tasting food, and some people simply soak the ingredients in wine to eat (such as snake gall). Although alcohol contained in wine can kill Sparganum, similar to the role of seasoning, many conditions are needed to completely kill Sparganum with alcohol contained in wine. For example, the research results show that only 60% ethanol can completely kill sparganium in food, the soaking time is at least 2 hours, and the volume of food must be very small. In fact, these conditions are difficult to meet at the same time, so drinking to kill insects is not reliable.
Conclusion: Eating frog meat infection may endanger cerebral sparganosis. But bullfrog is not a wild frog, so it doesn't need to give up completely because of sparganosis. Buying qualified frozen bullfrogs and cooking them thoroughly at high temperature can ensure that we don't have to worry about sparganosis while enjoying delicious frog legs.