Anisakidosis in humans

Many people know that fish is a rich source of easily digestible proteins and Omega-3 polyunsaturated fatty acids, which are essential for humans, thanks to the ubiquitous and incredibly inquisitive media. And the fact that fish contains many common and rare vitamins, as well as the lion's share of elements from the periodic table, does not surprise people much. Such information surrounds us everywhere: our teachers told us about it in biology lessons, fishmongers crucify us about it at the market, adherents of healthy eating write about it in magazines, even doctors in clinics advise eating more fish, replacing hard-to-digest meats with it. But is all fish so useful, or can this benefit also hide a great danger, the name of which is anisakiasis.

Can you get sick from eating fish?

Today we know that fish is a very valuable dietary product, which contains a huge amount of various substances that have a beneficial effect on our health. But people have been using fish and fish products as food for a long time, since the time when science existed at the stage of accumulating life experience. At first, it was at the level of a need for food, and over time, for many, it has already turned into a hobby.

An affordable product in all respects with various options for its processing and serving to the table attracts people of different sexes and ages. Low-fat fish varieties are recommended in dietary nutrition, and fatty ones are useful because they contain a unique component - fish oil, which contains polyunsaturated fatty acids Omega-3 and Omega-6, which help the normal functioning of the heart and blood vessels. In addition, fish oil improves brain function, ensures the health of the nervous system and organs of vision, helps strengthen the immune system, so it is recommended for baby food.

It is not surprising that fish is present on our table both on holidays and on weekdays, and more and more new dishes with this healthy product are appearing.

Such a lyrical description of the benefits of fish somehow does not fit with the word "danger", but this does not mean that it is absent. And in confirmation of this, doctors can cite a whole list of diseases caused by eating fish and various dishes from it, seafood, and delicacy meat of sea animals.

Most cases of illness from eating fish are due to poisoning associated with improper storage and preparation of fish, food poisoning (the most terrible of which is botulism) and helminthiasis ( opisthorchiasis, anisakiasis, diphyllobothriasis ).

As for helminthiasis, most often people talk about helminth infection from fish after eating river, i.e. freshwater fish, so many people consider sea fish to be quite safe in this regard. However, scientists have found that even sea fish living in salt water can become a source of parasites, so strict requirements must also be imposed on its processing.

Sea fish disease

Anisakiasis is a disease caused by the penetration of parasitic worms of the Anisakidae family into the human body (hence the name of helminthiasis). Anisakids, in turn, represent a large group of nematodes, i.e. roundworms that live in different types of fish. Thus, there are herring worms (genus Anisakis), cod worms (Pseudoterranova decipiens), flounder inhabitants (Larval anisakid), hyster parasites (Hysterothylacium), etc.

Anisakid worms are small parasites with a spindle-shaped body that tapers at the ends (especially in the head area where the 3 lips are located). The size of adults varies depending on gender. Females are usually larger and can reach 6.5 cm in length, while males are limited to 5 - 5.5 cm.

Parasites of the Anisakidae family can be found in herring, cod, perch, salmon fish, as well as in the bodies of other sea creatures (mollusks, shrimp, squid, octopus) - that is, in almost all the variety of sea fish and seafood that comes to the shelves of stores and markets.

It should be noted that small fish and crustaceans are considered only intermediate hosts of nematodes. During their life cycle, anicasids can change several hosts. The final host and distributor of parasitic infection in marine waters are large and predatory fish, marine mammals (dolphins, whales, seals, etc.), as well as fish-eating birds, in whose gastrointestinal tract the nematode larvae reach sexual maturity and reproduce, laying eggs in a transparent oval or round shell. An embryo is visible inside the egg.

Together with feces, nematode eggs fall into the water, where in favorable conditions (at a temperature of 5 to 21 degrees and sunny weather) the larvae mature. Depending on the environmental conditions, this takes from 3 days to 3 weeks. At the same time, the salt in soda is not a hindrance, but on the contrary, it increases the lifespan of the larvae hatched from the eggs. On average, they live in sea water for 3-3.5 months.

After the larvae leave the egg shell, they float freely in the water near the bottom of the reservoir, where they are swallowed by crustaceans. The crustaceans themselves are food for fish and squid, so the larva or sexually mature individual in the body of its first host gets to the second host. At the same time, nematodes and their larvae are resistant to an acidic environment, are not digested in the stomach of fish, but mature and parasitize in it.

Even if the fish dies, the larvae, in search of food, move from the gastrointestinal tract into eggs or milt, muscle tissue, and then into the water, where they can calmly wait for the next host.

Then, the infected fish or squid can become food for large predatory fish, marine mammals, fish-eating birds, in whose gastrointestinal tract and body they will continue their life activity, development, reproduction. Fish infected with nematodes can be caught by a person and end up on his table, and then the next host of the parasites becomes a person who is diagnosed with "anicasidosis".

It should be noted that the larvae of anikazid have adapted quite well to survival in adverse conditions. The salinity of the water does not matter to them, so both salt and freshwater bodies of water can become a habitat for nematodes. Larvae of 1-3 stages of maturation tolerate high temperatures well and die only at 60 degrees. And temperatures below zero are not scary for them. Thus, in fish frozen to a temperature of minus 18 degrees, larvae can survive for up to 2 weeks, and at minus 30, they die within 10 minutes.

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Causes anisakidosis

So, we already know that the source of human infection with nematodes from the Anisakidae family is fish that has not been heat treated or frozen at very low temperatures. But we must understand that we are not talking only about raw fish, which we are not accustomed to eating, unlike in the countries of the East, and Japan in particular.

According to statistics, the first case of the disease was detected in Holland more than half a century ago. But that was only the beginning. Today, anisakiasis has already become a problem in many countries in Europe, Southeast Asia, the USA, and Canada. Some traditions of the inhabitants of the Far East and northern regions of Russia also do not contribute to reducing the incidence of the disease, because eating raw, dried, smoked at temperatures below 60 degrees fish and caviar is one of the risk factors for anisakiasis.

The popularization of nutrition systems in our country, in which meat is recommended to be replaced by healthier and more easily digestible fish, leads to the need to somehow diversify our table, inventing new ways of cooking fish and seafood. But often we adopt the traditions of other countries, where fish has long been a popular food product (Japan, Korea, China, countries of Southeast Asia, etc.).

By the way, the Japanese traditional dish "sushi", which is gaining popularity in our country and often contains pieces of raw fish and seafood, is listed among the leading factors contributing to anisakidosis infection. It would seem that in this case, the Japanese should have become infected with anisakidosis en masse. Why is this not happening?

The fact is that the cautious Japanese have certain requirements for the preparation of fish dishes. River fish must be heat-treated. Only ocean and sea fish are included in sushi and other traditional Japanese dishes raw, and some types of fish (for example, salmon or tuna) must first be deep-frozen, which means the death of parasite larvae.

We, however, taking over the traditions of other countries, do not really care about observing such requirements. The ever-increasing demand for sushi and dishes made from virtually raw fish implies the creation of a large number of establishments where these dishes are prepared, but their owners do not really care about the health of visitors, because profit comes first. And a room decorated in Japanese style does not guarantee the quality of the products served in it.

Those who eat salted and pickled sea or ocean fish are at risk of anisakiasis. According to statistics, the level of helminth infection in fish from the Okhotsk, Barents and Baltic Seas reaches 45-100%. It would seem safer to buy ocean fish, but even here things are not so smooth, because fish caught in the Pacific or Atlantic Ocean are also often infected. At the same time, nematodes of the Anisakidae family were also found in almost 30% of caught Pacific squid.

Salted, smoked (especially cold smoked), dried, cured, marinated fish is consumed by both adults and children, which means that any fan of such food can get sick. However, children suffer from such diseases with intoxication and sensitization of the body more severely than adults. And then many careless parents with unconventional tastes begin to offer their children to try sushi or other fish delicacies.

But it is important to understand that for anisakid larvae it is not so important how salted the herring on our table is. They are not afraid of either salt or vinegar. Only deep freezing or sufficient heat treatment can destroy the parasites.

And it is not only herring, cod, salmon or salmon that can be infected with anisakids. Parasites are also found in other types of fish: capelin, halibut, flounder, various types of salmon, pollock, hake, blue whiting, mackerel, sardine, etc. It is clear that crustaceans (the same shrimp), squid, octopus, mussels, present on store shelves can also be infected. And this is far from the most pleasant news for fans of sea and ocean fish, as well as seafood delicacies.

Pathogenesis

A person becomes the final host of anisakid larvae, where they lose the ability to mature and produce offspring. But, given the rather long lifespan of young nematodes (they can exist in the human body from 2 weeks to 3 months), their parasitism in the human body cannot remain unnoticed.

The larvae are no longer excreted from the digestive system along with feces, but remain and parasitize in it. At the same time, they can change their location, making a hole in different parts of the gastrointestinal tract and penetrating into the abdominal cavity.

Since it is impossible to tell by eye whether a fish is a carrier of a parasitic infection, many will wonder if it is dangerous to eat fish at all, maybe it is worth giving up this tasty and healthy product? There is no need to go to extremes, because we already know that anicadosis larvae die when heated at a temperature above 60 degrees and frozen at a temperature below 30 degrees. It turns out that lovers of fried, boiled, stewed, baked fish have nothing to worry about, all the living creatures inside them die during heat treatment.

Frozen fish that has been kept at low temperatures for several months is also unlikely to become a source of anikazid, especially if it was gutted and placed in the freezer in time. It turns out that only fish that has not been frozen for a long time (or for a short time, but at a temperature below minus 30 degrees) or sufficiently heat-treated can become a source of parasitic infection. Thus, dangerous types of fish products include raw, salted (remember that larvae are not afraid of salt!) or marinated, dried, cured, smoked at low temperatures fish. These are the products that become sources of infection for humans and animals.

The first signs of anisakiasis may appear 1-2 weeks after eating contaminated food. During the incubation period, a person may not notice any changes in their health, and larvae that have not attached to the stomach walls may be released when coughing or vomiting. Then, young nematodes begin to settle in the lining of the gastrointestinal tract (mainly the stomach and small intestine, but some individuals can also be found in the walls of the pharynx and large intestine), penetrating the mucous and submucous layers with their head end.

At the sites of larval penetration, an inflammatory process occurs with the formation of seals formed by eosinophils (a type of leukocyte, the increase in the number of which is observed in allergic reactions and parasitic infections), the appearance of tissue edema, ulcers and small hemorrhages (hemorrhages). At the site of eosinophilic infiltrates (accumulation of eosinophils), granulomas (inflammatory nodules or tumors), foci of necrosis and perforation of the walls of organs (most often the intestines) are formed.

The development of an inflammatory reaction is associated not only with a violation of the integrity of the mucous membrane of the gastrointestinal tract, but also with the fact that the waste products of the larvae cause sensitization of the body. Which manifests itself in the form of various allergy symptoms (swelling, rash). Toxic-allergic effects on the body are also noted in the process of granuloma formation. And, despite the fact that the lifespan of anisakid larvae in the human body is limited to 2-3 months, symptoms of intoxication and sensitization of the body can manifest in a person for several months and years.

The inflammatory process, accompanied by irritation of the nerve endings in the intestinal walls and neuroreflex reactions (muscle spasm), often leads to organ obstruction. No less dangerous is the situation when the larvae cause intestinal perforation and become the cause of peritonitis (inflammation of the peritoneum).

Since the stomach and intestines communicate with other organs involved in the digestive process, it is not surprising that anikazid larvae, resistant to aggressive environments, can penetrate the gall bladder, pancreas, and liver ducts. In these organs, they also cause the development of inflammatory reactions and the appearance of granulomas.

When talking about the ways of infection with helminths of the Anisakidae family, it is necessary to take into account that in addition to eating thermally untreated infected fish, there are other ways to get an unfriendly "lodger". Eggs and larvae of the 1st degree are small in size (about 1 mm), so they may not be noticed in minced fish or when cutting fish. They can remain on the cutting board and the hands of the person who worked with the fish, and from there get on other products or into a person's mouth.

It is not for nothing that one of the important requirements for preventing helminthiasis is to use a separate cutting board for fish. It is also strictly not recommended to taste raw minced meat or whole fish for their degree of saltiness. After working with fish, hands should be washed with special care, and during work, try not to touch other food products with them, especially those that will not be subjected to heat treatment in the future. It just so happened that these living creatures, which serve as healthy food for humans, more often than others become carriers of all kinds of infections.

Symptoms anisakidosis

It is difficult to say when the first symptoms of illness will appear in a person who has eaten contaminated fish. Several hours or several days may pass, when the patient does not even remember what the gastrointestinal symptoms may be associated with. This is often the case, so many infected people simply do not associate their ill health with the fish.

What symptoms may indicate the introduction of anisakid into the gastrointestinal tract? Much depends on the localization of the parasite. Usually it is found in the lumen of the stomach, so the symptoms resemble the manifestations of gastroenterological diseases of the inflammatory type, occurring in an acute form (gastritis, stomach ulcer), or ordinary food poisoning.

Gastric anisakiasis may manifest itself in severe stomach pain, nausea, vomiting (blood is sometimes found in the vomit due to hemorrhages). Patients often complain of fever, and the temperature may be in the subfebrile range (37-38 degrees) or even higher. People with a tendency to allergies may experience allergic reactions (mild, such as urticaria, or severe, such as angioedema).

With intestinal localization of nematodes, pronounced symptoms of the disease do not always appear, and if they do, they are usually not as acute as with gastric localization of the parasite. Complaints may be received about pain in the umbilical or right iliac region, discomfort in the abdomen, increased gas formation.

In severe cases of gastrointestinal anisakiasis, its manifestations are largely similar to those of acute appendicitis. But there are other forms of the disease depending on the localization of the pathogen. So, from the stomach, nematodes can return back to the esophagus and pharynx, and the patient will feel a lump in the throat, irritation and pain when swallowing.

Returning to the oral cavity threatens migration of larvae into the bronchopulmonary system. In this case, symptoms that are not typical of poisoning or helminthiasis may appear: cough with scanty sputum, symptoms of broncho-obstruction, i.e. obstruction of the bronchi (hard, heavy breathing, wheezing and wheezing on exhalation). Pain in this case can be localized both along the esophagus and in the chest area, which is more reminiscent of bronchitis.

There were also reports of cases when the parasites were localized in the pharynx, penetrating the submucous layer, loose tissues of the tonsils, and even penetrated the tongue, which happens in the non-invasive form of the disease, if the larvae do not attach to the mucous and submucous layer, but move freely in the lumen of the gastrointestinal tract. In this case, doctors found swelling of the throat or tongue, and patients complained of pain in the throat, especially when trying to swallow, as happens with tonsillitis.

From the intestines and stomach, anikazid larvae can migrate to other organs of the digestive system. In this case, symptoms of pancreatitis (pressing pain on the left side of the abdomen just below the waist), cholecystitis (usually biliary colic), and liver inflammation (pain on the right, increased liver enzymes) may appear.

As we can see, the manifestations of anisakiasis can be so different that even an experienced doctor does not always make the correct diagnosis right away. The patient can be taken to the hospital with "appendicitis" in a severe course of the disease, suspected of having "bronchitis" in case of bronchopulmonary symptoms, or even treated for "Crohn's disease" in case of a vague clinical picture.

By the way, in the latter case the disease often takes a chronic course: nematode larvae die within 2-3 months, but under the influence of their waste products the body's sensitization increases, and it reacts particularly sharply to any negative factors, stimulating inflammatory processes. This usually causes exacerbations of symptoms in the absence of the pathogen itself.

Complications and consequences

Pain syndrome of any localization is a rather unpleasant thing, which significantly affects the quality of life of a person: it worsens the mood, contributes to rapid fatigue, reduces work capacity, causes irritability. If it does not pass for a long time, it can even cause depression. But with anisakisode, the pain syndrome can be either weak, annoying, or pronounced, painful, which in both cases is unpleasant.

And the very realization that a worm (and often more than one) lives inside you causes some people to feel a strong aversion to their own body, even to the point of vomiting and hysterics, which is typical for women. But the lack of information about the cause of the ailment also does not bode well. The variety of manifestations of the same disease sometimes becomes the cause of an incorrect diagnosis. It is clear that the prescribed treatment usually does not bring the desired result, but can only push the parasite to change its location.

An even greater danger is posed by a clinical picture in which the symptoms are very weakly expressed. A person may simply ignore them and not consult a doctor. The most meager symptoms are usually observed with intestinal localization of anikazid larvae. But here lies the greatest danger, since the introduction of parasites into the intestinal walls is fraught with its perforation and the release of contents into the abdominal cavity. And this in turn guarantees inflammation of the peritoneum, in other words, peritonitis, the danger of which we have already heard more than enough. So such an unpleasant neighborhood can even threaten a fatal outcome.

Other complications of anisakiasis may include exacerbations of existing gastrointestinal diseases (in particular, gastric and duodenal ulcers), stenosis (narrowing) of the ileum and intestinal obstruction. Migration of nematodes into the abdominal cavity, ovaries, liver, etc. may provoke inflammation and dysfunction of other organs.

Anaphylactic reactions caused by anisakid allergens in humans can be no less dangerous, especially in cases where the person already had a tendency to allergies to fish or seafood. Anaphylactic shock and Quincke's edema are sudden allergic reactions that pose a certain danger to human life.

Chronicization of the disease as a result of untimely treatment or its absence can also be considered as an extremely unpleasant complication (although it is often a case of incorrect diagnosis and then it is necessary to treat something completely different from what actually exists). In this case, the life cycle of the larvae can end much earlier than the last symptoms go away. Some patients complain for six months or more, and the transition of the disease to a chronic form threatens the appearance of signs of the disease within several years.

This prospect once again shows that one cannot be careless about one’s health, and parasites have no place in the human body.

Diagnostics anisakidosis

So, we have gradually approached the issue of the need for timely diagnosis of anisakiasis, which makes it possible to get rid of nematodes as quickly as possible and restore the normal functioning of the digestive system (and sometimes not only it). It remains to understand what methods doctors use to detect parasites inside a person and how to test for anisakiasis.

If you have symptoms of illness and there is a suspicion that it is related to eating fish, you should not think for a long time about which doctor to contact with the problem. It is important to contact a therapist or family doctor as soon as possible, and he will then give a referral to a parasitologist or gastroenterologist (depending on which doctor is available at the hospital).

Regardless of whether the patient came to the hospital on his own or was brought by an ambulance, the doctor will first of all be interested in the symptoms that have appeared, and after listening to the complaints and visually assessing the patient's condition, he will want to know details about the patient's diet in the coming days. If you know that over the past couple of weeks you have eaten sushi, raw, dried, salted, smoked fish or fish and seafood dishes that were not pre-cooked sufficiently, you must definitely tell the doctor about this. Such foresight will reduce the likelihood of an erroneous diagnosis, especially if the reason for visiting a doctor was complaints of a sore throat or cough without cause, and not gastrointestinal symptoms.

Usually, when there are complaints about gastrointestinal pathologies, doctors prescribe certain laboratory tests. In the absence of vomiting, these will be: a general blood test, urine and feces analysis. If there is vomiting, vomit can also be taken for analysis.

It should be said that laboratory tests do not always allow detecting anisakid larvae. They are more likely to be detected in vomit, while they are found in feces in isolated cases if the parasite has settled in the lumen of the large intestine (but it prefers the small intestine). Usually, a blood test is prescribed to detect intra-tissue parasites, and a stool test helps to detect helminth eggs. But we already know that anisakid worms do not reproduce in the human body, which means that their eggs will not be detected in feces.

As for the blood test, antibodies (during the enzyme immunoassay) produced by our body in response to infection can be detected in it. Such a test is prescribed if intra-tissue parasites are suspected. But the problem is that anisakids cannot be attributed to either of the 2 types of helminths with certainty, so relying only on the test results would be illogical. For example, a characteristic increase in the level of leukocytes, and in particular eosinophils, determined during a clinical blood test, is observed in various helminthiases and does not give an idea of which parasite caused the disease. In addition, a similar picture can also be observed in the acute course of allergic reactions, infections, gastrointestinal diseases, etc.

It may seem logical to ask the question, why do they prescribe tests at all if their results do not provide the necessary information? The need for such studies can be explained by the fact that initially the doctor cannot say with certainty that the patient's ill health is associated with anicasidosis or any other helminthiasis, so he considers any options and reasons. In addition, the test results will be useful when the patient needs to be prescribed treatment, because they can tell the doctor about the patient's body condition and possible disorders in it, which will be an obstacle to prescribing specific drugs.

Scientists consider the most specific tests to be those for anisakid allergens (skin prick test) and the basophil transformation test with an extract of nematodes of the Anisakidae family.

Instrumental diagnostics is considered even more informative than conventional tests for anisakiasis. Doctors have 2 popular methods that allow identifying larvae that have penetrated the mucous membranes of the gastrointestinal tract: radiography using contrast (especially in the gastric form of the disease) and fibrogastroscopy (endoscopy). In the second case, it is even possible to take biomaterial (biopsy) for further examination if swelling and multiple small erosions are visible on the mucous membrane of the stomach, esophagus or intestines (the parasite is unlikely to be there in splendid isolation).

It should be said that endoscopy allows not only to detect anisakid larvae and conduct a more detailed study to determine the localization of parasites, but also to immediately remove those individuals that will be visible through the translucent mucous and submucous layers. This is why such a study is more preferable, especially considering that effective methods of drug treatment of anisakidosis have not yet been developed.

Anisakiasis with traditional gastrointestinal localization should be differentiated from gastric and duodenal ulcers, exacerbation of gastritis, pancreatitis, cholecystitis. Similar symptoms can manifest themselves in acute food poisoning, appendicitis, colitis, diverticulitis, tumors in the stomach or intestines. In addition, other helminthiases can occur with similar symptoms.

Extraintestinal forms of anisakiasis are similar to acute and tuberculous peritonitis, pancreatic cancer. When helminths return to the pharynx and larynx, it is very important not to give in to the first impulse and not to diagnose tonsillitis or bronchitis, the treatment of which will certainly not help the patient.

The similarity of anisakiasis symptoms with various unrelated diseases only confirms the necessity and value of differential diagnostics. However, despite the developed diagnostic methods, the majority of cases of anisakiasis remain unrecognized.

Prevention

Needless to say, we are considering a very unpleasant and to a certain extent dangerous disease, the effective treatment of which, given the sufficient prevalence of helminthiasis, has not yet been developed. In such circumstances, the most correct thing to do is to observe caution and preventive measures that help prevent the disease.

It should be noted that these measures are very simple, but for the sake of health, you may still have to give up some food preferences:

• It is recommended, if possible, to consume fish from proven water bodies where parasites have not been found. And even in this situation, freshly caught fish should be gutted and washed as quickly as possible while it is still alive, because in dead fish parasites pass into the eggs, milt and meat of the fish, where they are more difficult to detect.
• If the fish is purchased at retail outlets and its whereabouts are unknown, the best thing to do is to subject it to sufficient heat treatment: boil, bake, fry, etc.
• For lovers of salted, marinated and smoked fish, it is recommended to cook it yourself, provided that fresh fish is pre-frozen at a temperature no higher than minus 18 degrees for 2 weeks. At lower temperatures, the freezing period of fish can be reduced (however, not everyone has the opportunity to deep freeze fish).
• You should buy ready-made salted, marinated and smoked fish in those retail outlets where the products are checked for the presence of helminths and other parasites. Do not forget that salt and marinades do not kill anisakids.
• You should never taste raw minced fish or pieces of fish for salt. At the same time, you should have a separate board in the kitchen on which only fish and seafood will be cut. It would also be good to have separate dishes and a knife for these purposes, if there are none, then after cutting the fish, the dishes and kitchen utensils should be subjected to heat treatment.
• In the refrigerator, fresh and salted fish should be kept separate from products that will not be subsequently subjected to heat treatment (gastronomy, cooking, chopped vegetables, etc.). This also applies to freezers, if the temperature in them is lower than recommended for the rapid death of nematodes.
• Sushi and other overseas delicacies from fish and seafood lovers should understand that they are putting themselves in danger, especially when visiting dubious establishments or trying to cook such dishes at home without knowledge of technologies and safety precautions. Moreover, it is not worth accustoming children to such "delicacies", for whom the optimal delicacy would be boiled or baked fish that has been heat-treated at a temperature of at least 60 degrees for 20 or more minutes.

Anicasidosis is not the only parasitic disease that can be contracted as a result of eating sea or river fish. Therefore, when thinking about the benefits of this product for our body, we must not forget about the danger that can lurk inside the aquatic inhabitants of fresh and salt water bodies. Moreover, there are many ways to benefit from fish without harming yourself and your loved ones.

Forecast

Anisakiasis is a parasitic disease that can have different incubation periods and features of the course. And it is good if a person seeks help in the first hours or days after infection, while the harm from the introduction of anisakid is minimal. In this case, the treatment prognosis is favorable, although much also depends on the concentration of parasites and the form of the disease (the invasive form usually proceeds and is treated more difficultly than the non-invasive), the treatment used. You cannot wait until the larvae die naturally, because during their stay in the human body they can cause a lot of harm, and the consequences of their vital activity will have to be treated for more than one month.

The prognosis significantly worsens as the nematodes migrate and penetrate deeper into the tissues of the organs. A severe form of the disease, which has negative consequences, is observed when the intestinal walls are perforated or helminths penetrate into the lungs.