Fish parasites: what are they, how to recognize them, parasite diseases

Parasites in fish are dangerous to humans (photo)

No matter how much they talk about the benefits of fish for the human body, which is achieved due to the content of useful microelements in it. such as iodine or phosphorus, we should never forget that its use can also cause not very pleasant consequences. It is not the product itself that causes harm to health, but the possible content of harmful parasites in it, which subsequently develop in the human body.

Not all parasites are dangerous, but some are. Usually, with insufficient heat treatment, parasites retain their viability. Fans of sushi and rolls are especially susceptible to infection with infectious diseases, since raw fish is mainly used for their preparation.

So which parasites cause serious harm to human health: What are the symptoms and how to avoid it?

Opisthorchiasis

The causative agent of the disease here is the cat fluke. Moreover, the carriers are not only some species of fish (mainly from the carp family), but also cats and dogs. If you eat infected fish within a few weeks after the parasite enters its body, you should know that opisthorchiasis larvae enter the gastrointestinal tract on 10–12 .

At this point, they begin to parasitize the liver and gall bladder, and reach sexual maturity in about a month.

Symptoms of the presence of opisthorchiasis in the body, as a rule, are: an increase in body temperature to 38–40 degrees, allergic skin rashes, gastrointestinal disorders, bloating and nausea. After some time, the acute symptoms become weaker, and the chronic course of the disease begins. If treatment is not started immediately, opisthorchiasis can parasitize the human body for several years and subsequently negatively affect all vital organs.

Diphyllobothriasis

This disease is caused by the presence of a tapeworm in the body, which can also live inside a person for many years and continue to grow. History has recorded cases when the length of the parasite reached 12 meters. Favorite fish species of tapeworms are Far Eastern salmon, river representatives, as well as pike and perch.

Symptoms of diphyllobothriasis are bloating, nausea, heartburn, diarrhea, and allergic skin reactions. In the chronic course of the disease, consequences for other body systems may also be negative.

Clonorchiasis

The Chinese fluke is the same parasite that causes clonorchiasis. Based on the name, you can guess that fish brought from the Chinese and Korean shores, as well as those caught on the Amur, can easily be a carrier of this infection.

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When it enters the human body, it has similar symptoms to opisthorchiasis. In addition, the liver may become enlarged and pain in the right hypochondrium may occur.

Anisakidosis

The parasites that cause this disease love to live in red fish, so roll lovers should be especially careful. The symptoms are similar to those of poisoning, especially in the gastrointestinal tract. If anisacidosis is not treated in time, you can develop a stomach ulcer.

Is it possible to eat fish with tapeworm?

Fresh fish caught should be carefully processed. To do this, rinse it well under running water and clean all the insides . It should be noted that such treatment is not a guarantee of safety if an individual has a mature worm.

This parasite can settle deep in the tissues of its host, and to continue its kind, lay a mass of eggs in different parts of the carcass. The larvae very resistant to external influences and if they are present, it is quite difficult to avoid infection.

When cutting sick fish, you should also remember that eggs can also settle the accessories used to cut and clean the carcass . Dishes and equipment should be washed under hot running water with laundry soap or chemical dishwashing detergent.

The most dangerous consequence of eating contaminated fish is diphyllobothriasis. The parasitic disease affects the organs of the gastrointestinal tract and causes megaloblastic anemia . Fatalities have been reported due to intestinal obstruction.

If you follow simple recommendations, infection can be completely avoided :

• carefully monitor the rules of personal hygiene and thoroughly wash your hands before eating any food, including fish;
• do not catch fish in polluted waters, since it is in sewage waters that the parasite most often likes to live;
• Avoid eating raw or questionably processed fish;
• For safety reasons, do not consume sushi products; it is better to make these dishes yourself according to all accepted safety rules.

Which parasites are not harmful?

Despite the possibility of contracting infectious diseases due to the presence of parasites in the fish’s body, not all of them are dangerous to your health.

1. Ligula. If this worm is found inside a fish, it is enough to simply remove it. The presence of a helminth in a fish body does not give negative consequences, since it does not have the ability to penetrate muscle tissue and develop vigorous vital activity within it. However, it is better to heat treat the fish if you suddenly find such an unpleasant lodger in its body. Both freezing and boiling the product are suitable.
2. Schistocephamos. The favorite habitat of this type of parasite is the intestines of red fish (trout, salmon). Getting rid of them is easy: you just need to know how to clean fish. Clean the fish from the internal organs, but try to make sure that the offal is not found by animals: schistocephamos is a helminth that gets along well in their body.
3. Cystidicola pharyonis. Just like the previous parasite, it loves the abdominal cavity. Simply remove the giblets and boil the fish. It does not take root in the human body.
4. Trienophorus nodulosus. This type of worm infects the liver of fish. The measures to remove it are the same as in the previous example: clean the peritoneal cavity and boil the fish itself.
5. Philometra. This type of worm can hide not only inside, but also under the scales and in the gill area. You will have to clear out illegal settlers manually, and after that it is better to boil the fish. They are not parasitic in the human body. They prefer the carp family.

External signs of tapeworm fish

It is often impossible to determine the presence of tapeworms or larvae in the inhabitants of rivers and lakes by appearance, especially if they have already been gutted.

You can recognize parasites in fish when cutting it

However, whether a product is dangerous can be determined by several signs:

1. If the fish is not gutted, larvae or adult worms can be seen in its entrails. Most often they look like transparent or cloudy beads with a diameter ranging from fractions of a millimeter to several millimeters. They are located on the outer lining of the intestines, on the swim bladder, and on the gills. Helminthiasis is also expressed in the presence of white or pinkish worms twisted into a spiral on the internal organs of fish.
2. Whole, not yet gutted fish infected with tapeworms often have an excessively swollen abdomen. When you press it, the volume does not decrease. In most cases, when gutted, white or cream-colored ribbons are found in the insides (this is what tapeworm looks like in fish). The worm has a more modest size than that of large animals. Its segments look smooth, and the edges are slightly wavy. Often, after being removed from the abdomen, the worm continues to move weakly for some time, but later dies.
3. When cutting ready-made fish fillets, small spherical formations are found in the thickness. Often they are almost the same color as muscles, but have a slightly different structure. Due to the small size of the larvae, it can be extremely difficult to detect them.

A bloated belly may indicate the presence of parasites in fish.

Indirect signs of the presence of worms in fish are considered to be the small body size of a potential carrier relative to the head, which may indicate exhaustion or developmental delay. However, this feature does not always “work”, since some species of fish by nature have a large head and a small body. A much more obvious sign is the lack of fat deposits in the inhabitants of fresh water bodies. They are usually concentrated in the abdominal area. If, despite the season, there is no fat, most likely there are helminths in the fish.

If a fish is found to have helminthiasis, it is not recommended to throw it away. It is necessary to wrap it in a thick film and bury it to a depth of 50 cm so that it is not dug up by domestic or wild animals.

Worms dangerous to the human body

Among all of the above infection carriers, Diphyllobothrium latum and Diphyllobothrium dendrite should be distinguished. The favorite fish of these worms are perch, pike, burbot, as well as their derivatives: caviar, liver, etc.

Worms of the nematode group, the size of which does not exceed 5 mm, are also at risk. The symptoms of infection with these parasites are similar to all others: diarrhea (or, conversely, constipation), bloating, nausea, gastrointestinal dysfunction. If you find this kind of worms inside a fish, get rid of it, since no heat treatment will help in this case.

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How can you tell if your fish is infected with parasites?

Of course, it is possible to detect the presence of parasites in a fish’s body. There are a number of distinctive features for this:

• drying of the mucous membrane of the organs of vision;
• changes in tissue structures: if you press on the fish, a dent will remain;
• swelling in the abdominal area;
• very unpleasant smell when cutting;
• gills may be marsh-colored;
• mucus-like discharge from the anus;
• when boiling, the presence of foreign particles in the broth, as well as its unusual color.

What diseases are dangerous

Diphyllobothriasis is perhaps one of the most dangerous diseases that a person becomes infected with when eating fish with parasites inside. The thing is that tapeworms, which develop as they remain in the human body, can compress internal organs and thereby lead to dysfunction.

Infections leading to kidney and liver failure, such as opisthorchiasis, also do not bring any benefit to humans. Moreover, other than surgical intervention to remove pathogens from the human body, there are no ways to cure these diseases.

Based on all of the above, the conclusion suggests itself: before eating fish, be sure to check it for the presence of parasitic organisms inside. If you have little experience in this, look on the Internet for photos of fish parasites that are dangerous to humans.

If you have even the slightest suspicion that the fish is infected, it is better not to risk it, but simply get rid of it.

Author of the publication

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Nika

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I am interested in hiking and traveling, photography and videography. I have been going hiking since childhood. The whole family went and went - sometimes to the sea, then to the river, to the lake, to the forest. There was a time when we spent a whole month in the forest. We lived in tents and cooked over fires. This is probably why I am still drawn to the forest and, in general, to nature. I travel regularly. About three trips a year for 10-15 days and many 2 and 3 day hikes.

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How to properly process fish to avoid infection?

In accordance with SanPiN 3.2.3215-14 “Prevention of parasitic diseases on the territory of the Russian Federation,” fish and fish products can be disinfected by freezing, salting and heat treatment.

To destroy nematode larvae, fish must be frozen for 24 hours at a temperature of -20 degrees. On average, the temperature in the freezer of a regular refrigerator is only -18 degrees. In this case, it will take longer to freeze the helminths: 10-14 days.

Trematode larvae (in particular, opisthorchids) die at a temperature of -28 degrees, and the fish must be frozen for at least 32 hours. At a similar temperature, cystode larvae are also destroyed: freezing should last for 72 hours.

In addition, you can disinfect fish in boiling water; to do this, you need to cook it for 20 minutes after boiling, crayfish - 15-20 minutes. You can salt fish weighing up to 2 kg. To do this, add 20% salt to the weight of the fish and salt it for 7 to 14 days.