Helminths: which are dangerous parasitic worms for humans

According to the WHO, every year every second person on the planet is infected with helminths. Many people believe that parasitic worms are not very harmful to health. However, not everything is so simple: helminths can infect important internal organs: heart, lungs, brain.

Helminths - who are they?

Helminths are parasitic worms that can choose the body of a person, animal, plant as a host. There are a total of three classes of helminths:

  • tapeworms.This class includes about 3, 5 thousand species of helminths. The length of parasitic worms varies from a few mm to 10-15 meters;
  • methyls.The parasites got their name because of the presence of shoots, with the help of which they receive nutrients. The human body can infect about 4 dozen species of flukes. As a rule, the length of the worms does not exceed 5 cm;
  • roundworms.This class of helminths has more than 24 thousand species. Roundworms have a spindle shape. Usually their length is not more than 0, 5 meters.

You can get helminths in different ways. Most often, however, parasitic invasion occurs for the following reasons:

  1. Poor hand hygiene.
  2. Unwashed vegetables, fruits; insufficient or insufficient meat, fish - the use of such products increases the risk of parasitic infection.
  3. Keep food open outside the refrigerator. Insects are able to transfer helminth eggs to food that is stored without packaging.
  4. Contact with pets.
causes of infection of the body with parasites

The main symptoms of the presence of parasites in the body:

  • nausea, vomiting, diarrhea;
  • weight loss;
  • allergic rashes;
  • bloating;
  • itching in the anus;
  • gnashing of teeth in a dream.

What helminths are most common in Russia? Think about the most common types of parasitic worms and the diseases they cause.


The body of the tapeworm consists of members, the total number of which varies from 3 to 5000. The main element of fixing the helminth is the head, additional are suction cups, hooks.

The most common causes of tapeworms are:

  • diphyllobotriasis;
  • teniarinosis;
  • teniasis.
tapeworm, a parasite of the human body


The cause of the disease is extensive tapeworm, which affects the human intestine. The development of worm eggs occurs in fresh water. The scheme of the appearance of tapeworm in the human body is as follows:

  • The worm's eggs are swallowed by crustaceans that live in the tank.
  • Infected crustaceans are eaten by fish.
  • A person becomes infected with a parasite by eating fish that has undergone insufficient heat treatment.

The symptoms of the disease develop 1, 5 months after infection. The main sign of the pathology is the presence of whitish fragments of helminths in the stool.

Attaching to the intestinal mucosa, tapeworm absorbs large amounts of vitamin B12. For this reason, people with diphyllobotriasis often develop anemia. In addition, tapeworm can cause enlargement of the liver, spleen, intestinal obstruction.


The cause of the disease is bovine tapeworm, which lives mainly in the small intestine of man. During its development cycle, the helminth replaces two hosts: the intermediate is bovine and the main is human. Beef tapeworm can live in the body for 20 years, multiplying and causing damage to health.

Usually people develop teniarinosis after eating unprocessed or insufficient beef.

The disease often occurs without symptoms and is discovered by chance when a person sees elements of helminths in his stool. In some people, in addition to the main signs of helminth infection, a pain syndrome may appear on the right side of the anterior abdominal wall.

Adult helminths are able to penetrate the appendix, pancreatic duct, bile ducts, provoking acute inflammatory processes in them. With many parasitic infestations, intestinal obstruction can develop.

large tapeworm parasite


The cause of the disease is swine tapeworm, which initially affects the small intestine of humans. Human infection occurs through the consumption of raw or improperly cooked pork.

The parasite can penetrate various organs and tissues, causing pain in the abdomen, back, limbs. The pathology is most favorable when the worm is localized in the subcutaneous adipose tissue and skeletal muscle tissue. When worms enter the eye muscles, they cause decreased visual acuity, tearing and photophobia. Damage to the porcine chain of the brain can be fatal.


The flukes are leaf-shaped and have a high ability to reproduce at different periods of the life cycle. The reproduction of worms is possible not only sexually with fertilization, but also without it. In addition to shoots, worms have many hooks and thorns, so they are securely attached to the mucous membranes of organs.

parasitic species of methyl

Common pathologies caused by flukes:

  • fascioliasis;
  • opisthorchiasis;
  • paragonimiasis.


Fascioliasis occurs when the liver or gallbladder is damaged by the liver fluke. In general, the infection occurs when eating vegetables for which water from open tanks has been used.

In addition to the standard signs of a parasitic infection, a person may experience asthma attacks, which are accompanied by shortness of breath, flushing, dilated pupils and tachycardia. If an adult has caused a blockage in the bile ducts, then obstructive jaundice develops. Signs of pathology:

  • perceiving pain in the right hypochondrium;
  • yellowing of the skin;
  • fever;
  • colorless stools.


The cause of the disease is feline methyl. The name of the parasite is due to the fact that in addition to humans, it often infects cats and other mammals that eat fish.

feline methyl parasite

As a rule, feline flukes affect the liver and pancreas, causing inflammation in the organs. The symptoms are different and depend on the number of parasites. The patient may experience:

  • symptoms of intoxication;
  • fever;
  • beehives;
  • itchy skin;
  • pain in muscles, joints, right hypochondrium.

In some cases, helminths cause enlarged lymph nodes, the development of jaundice. The chronic form of the pathology often leads to hepatitis, liver cirrhosis.


The culprit of the disease is pulmonary methyl, which enters the human body with infected crustaceans.

First the parasite enters the human intestine, then the abdominal cavity. The end point of his journey is lung tissue. In addition, the worm is able to penetrate the brain and affect the central nervous system.

parasitic pulmonary methyl

Specific signs of parasitic invasion of the lungs:

  • chest pain;
  • sputum cough, which may contain pus and blood;
  • fever.

In some cases, helminths cause impaired ventilation of the lungs and gas exchange during respiration.


Due to their structure, roundworms (nematodes) are able to survive even in extreme conditions. Their body is covered with a three-layer musculoskeletal sac, which reliably protects the parasites from external influences.

type of parasitic roundworms

Common diseases caused by nematodes:

  • ascariasis;
  • enterobiosis;
  • trichinosis.


The development of the disease provokes roundworm, which is initially fixed in the small intestine. The average length of adults is 40 cm. The larvae of the parasite can enter the human digestive system with unwashed vegetables and fruits, contaminated water. Also, poorly washed hands before eating are often the cause of ascariasis.

During the penetration of larvae into the human body, subfebrile fever, allergic rashes and cough with clear sputum can be observed. Signs of the intestinal stage of ascariasis (diarrhea, abdominal pain) are observed only in the presence of several parasites. As a rule, life in the intestine of a worm is asymptomatic.

Complications with multiple parasitic infestations:

  • bile duct obstruction;
  • purulent inflammatory processes in the gallbladder, liver;
  • inflammation of the appendix;
  • intestinal obstruction.


The provokers of the disease are pinworms - small worms up to 1 cm long. Helminths penetrate the human digestive system in the same way as roundworms.

parasites of human pinworms

Currently, enterobiosis is the most common parasitic pathology in the world. In general, the disease is diagnosed in children under 10 years of age.

Symptoms, as in previous cases, develop only in multiple parasitic infestations. Children often have diarrhea, mucus in the stool, difficult and painful digestion, itchy anus and nausea. In severe disease, limb cramps may occur. In addition, pinworms are able to penetrate the genitals, causing acute inflammation in them.


This disease provokes Trichinella - one of the smallest parasitic worms. The length of the parasite rarely exceeds 4 mm. In the larval stage, worms can infect skeletal muscle. The exception is the myocardium - the muscle tissue of the heart. Adults parasitize in the small intestine.

As a rule, human infection occurs when eating half-roasted pork. At the same time for the development of the disease is enough to consume only 30 g of meat affected by parasites.

The pathology is manifested by the standard symptoms of parasitic invasion. Swelling of the eyelids, face, arms and legs, lower back pain, masticatory muscles may occur at an advanced stage. Possible complications are complete or partial loss of mobility, airway paralysis.

How to avoid helminth infection?

To reduce the risk of parasitic worm infections, it is important to follow these guidelines:

  1. Wash your hands thoroughly before eating, after visiting the street, public places.
  2. Follow the correct technology for cooking meat, fish. The heat treatment of meat and fish products must last at least 20 minutes.
  3. Do not eat dried or dried fish.
  4. Performs deworming of pets.
  5. Get tested regularly, even if you have no pathological signs. The most common diagnostic methods are macroscopic and microscopic examination of the stool. The first method allows you to detect adults, and the second - eggs and larvae of worms.