Helminths: which are dangerous parasitic worms for humans

According to the WHO, every year every other person on the planet is infected with helminths. Many people think 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, animals, plants 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;
  • flukes.The parasites got their name due to the presence of teats, with the help of which they get nutrients. The human body can infect about 4 dozen species of flukes. The length of the worm as a rule is not more than 5 cm;
  • roundworms.This class of helminths has more than 24 thousand species. Roundworms are spindle-shaped. Usually their length is not more than 0. 5 meters.

You can get helminths in a variety of ways. However, the most common parasitic invasion occurs for the following reasons:

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

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

  • nausea, vomiting, diarrhea;
  • weight loss;
  • allergic rash;
  • bloating;
  • itching in the anus;
  • grinding teeth in sleep.

Which helminths are the most common in Russia? Consider the most common types of parasitic worms and the diseases they cause.


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

The most common causes of tapeworms are:

  • diphyllobotriasis;
  • teniarinhoses;
  • teniasis.
tapeworm, a parasite in the human body


The cause of the disease is a broad tapeworm that affects the human intestine. The development of worm eggs takes place in fresh water. The scheme of tapeworm entry into the human body is as follows:

  • Worm eggs are swallowed by crabs that live in the tank.
  • Infected crabs are eaten by fish.
  • A person becomes infected with the parasite by eating fish that has undergone insufficient heat treatment.

The symptomatology of the disease develops 1, 5 months after infection. The main sign of pathology is the presence of whitish fragments of helminths in the feces.

By attaching to the intestinal mucosa, tapeworm absorbs a large amount 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 causative agent of the disease is bovine tapeworm, which predominantly lives in the human small intestine. During its development cycle, the helminth replaces two hosts: the intermediate is cattle, the main man. Bovine tapeworm can live in the body for 20 years, multiplying and causing damage to health.

Typically, people develop teniarinhosis after eating undercooked or undercooked beef.

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

Adult helminths are able to penetrate the appendix, pancreatic duct, biliary tract, causing acute inflammatory processes in them. In multiple parasitic infections, intestinal obstruction may develop.

bovine tapeworm parasite


The causative agent of the disease is swine tapeworm, which initially affects the small intestine of man. Human infection occurs by consuming 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 fat and bone muscle tissue. When worms penetrate the eye muscles, they cause a decrease in visual acuity, lacrimation and photophobia. Defeat of the pig chain brain can be fatal.

Naive people

Flakes are leaf-shaped and have a high ability to reproduce at different periods of the life cycle. Worm reproduction is possible not only sexually by fertilization, but also without it. In addition to mammals, worms have many hooks and spines, due to which they are reliably attached to the mucous membrane of organs.

a species of fluke parasite

Common pathologies caused by flukes:

  • fascioliasis;
  • opisthorchiasis;
  • paragonimiasis.


Fascioliasis occurs when the liver or gallbladder is damaged by liver fluke. Basically, the infection occurs when eating vegetables, for which water was used from open tanks.

In addition to the standard signs of parasite infection, a person may experience asthma attacks accompanied by shortness of breath, redness of the face, dilated pupils and tachycardia. If an adult has caused bile duct obstruction, then obstructive jaundice develops. Signs of pathology:

  • cramping pains in the right hypochondrium;
  • yellowing of the skin;
  • fever;
  • colorless feces.


The cause of the disease is the feline fluke. 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 fluke parasite

Cat flu is typically affecting 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;
  • hives;
  • itchy skin;
  • pain in muscles, joints, right hypochondrium.

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


The culprit of the disease is the pulmonary fluke, which enters the human body by infected cancers.

First the parasite enters the human intestine and 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.

pulmonary fluke parasite

Specific signs of parasitic lung invasion:

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

In some cases, helminths cause a violation of the ventilatory function of the lungs and the exchange of gases during respiration.


Thanks to their structure, roundworms (nematodes) can survive even in extreme conditions. Their body is covered with a three-layer musculocutaneous sac that reliably protects parasites from external influences.

a species of parasitic roundworm

Common diseases caused by nematodes:

  • ascariasis;
  • enterobiasis;
  • trichinosis.


The development of the disease is provoked by ascaris, 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 with 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 rash, and cough with clear sputum discharge may be observed. Signs of intestinal stage ascariasis (diarrhea, abdominal pain) are observed only in the presence of several parasites. Life in the intestines of a single worm is generally asymptomatic.

Complications with multiple parasitic attacks:

  • bile duct obstruction;
  • purulent inflammatory processes in the gallbladder, liver;
  • appendicitis;
  • intestinal obstruction.


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.

human pinworm parasites

Currently, enterobiasis is the most common parasitic pathology in the world. Basically, the disease is diagnosed in children under 10 years of age.

Symptoms, as in previous cases, develop only in multiple parasitic infections. Children often have diarrhea, mucus in the stool, difficult and painful digestion, itching in the anus, and nausea. With severe disease, limb cramps can 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 muscles. The exception is the myocardium - the muscle tissue of the heart. Adults parasitize on the small intestine.

Human infection usually occurs when you eat half-baked pork. At the same time, for the development of the disease, it is enough to consume only 30 g of meat affected by parasites.

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

How to avoid helminth infection?

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

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