Helminths: which parasitic worms are dangerous to humans

According to the WHO, every year one in two people on the planet is infected by 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, animal or plant as a host. There are three classes of helminths in total:

  • tapeworms.This class includes about 3, 500 types of helminths. The length of parasitic worms varies from a few mm to 10-15 meters;
  • chance.The parasites have earned this name due to the presence of suckers, with the help of which they receive nutrients. The human body can infect about 4 dozen species of worms. As a rule, the worms do not exceed 5 cm in length;
  • round worms.This class of helminths has more than 24 thousand species. Roundworms are spindle-shaped. Normally, its length does not exceed 0. 5 meters.

You can be infected by helminths in several ways. However, most of the time parasitic invasion occurs for the following reasons:

  1. Poor hand hygiene.
  2. Vegetables, unwashed fruits; rare or rare meat, fish - the use of such products often increases the risk of parasitic infestation.
  3. Keep food open outside the refrigerator. Insects are capable of transferring helminth eggs to food 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 skin rashes;
  • swelling;
  • itching in the anus;
  • gnashing teeth in a dream.

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


The body of the tapeworm is made up of limbs, the total number of which ranges from 3 to 5. 000. The main fixing element of the helminths is the head, the additional ones are suction cups, hooks.

The most common causes of tapeworms are:

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


The causative agent of the disease is a wide tapeworm that affects the human intestine. The development of worm eggs occurs in fresh water. The scheme of the tapeworm entering the human body is as follows:

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

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

Binding to the intestinal mucosa, the tapeworm absorbs a large amount of vitamin B12. For this reason, people with diphyllobotriasis often develop anemia. In addition, the tapeworm can cause an increase in the liver, spleen, intestinal obstruction.


The causative agent of the disease is bovine tapeworm, which lives predominantly in the human small intestine. During its development cycle, helminths replace two hosts: the intermediate is cattle, the main one is man. Bovine tapeworms can live in the body for 20 years, multiplying and causing damage to health.

Typically, people develop teniarinhoses after eating rare or rare meat.

The disease often goes on without pronounced symptoms and is detected by chance when a person sees elements of helminth in their stool. In some people, in addition to the main signs of helminth infection, the painful syndrome can occur on the right side of the anterior abdominal wall.

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

bovine tapeworm parasite


The causative agent of the disease is the pig's tapeworm, which initially affects the human small intestine. Human infection occurs through the consumption of raw or undercooked pork.

The parasite can penetrate various organs and tissues, causing pain in the abdomen, back and limbs. Pathology is most favorable when the worm is located in subcutaneous fat and skeletal muscle tissue. When worms penetrate the eye muscles, they cause a decrease in visual acuity, tearing and photophobia. Defeating the brain's pig chain can be fatal.


The worms are leaf-shaped and have a high ability to reproduce at different periods in the life cycle. The reproduction of worms is possible not only sexually with fertilization, but also without it. In addition to suckers, worms have many hooks and spines, due to which they attach themselves reliably to the mucous membranes of the organs.

lucky parasite species

Common pathologies caused by worms:

  • fascioliasis;
  • opistorchiasis;
  • paragonimiasis.


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

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

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


The causative agent of the disease is a feline chance. The name of the parasite is due to the fact that, in addition to man, it usually infects cats and other mammals that feed on fish.

feline parasite chance

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

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

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


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

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

lung 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 ventilation function of the lungs and gas exchange during breathing.

Round worms

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

type of parasitic roundworms

Common diseases caused by nematodes:

  • ascariasis;
  • enterobiasis;
  • trichinosis.


The development of the disease causes ascaris, which initially fixes itself in the small intestine. The average length of adults is 40 cm. The larvae of the parasite can enter the human digestive system with vegetables and fruits not washed, contaminated water. In addition, poorly washed hands before eating are often the cause of ascariasis.

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

Complications with multiple parasitic infestations:

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


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

human moth parasites

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

Symptoms, as in previous cases, develop only with multiple parasitic infestations. Children often have diarrhea, mucus in the stools, difficult and painful digestion, itching in the anus and nausea. With a severe course of the disease, cramps in the limbs can occur. In addition, pinworms are able to penetrate the genitals, causing acute inflammation in them.


This disease causes Trichinella - one of the smallest parasitic worms. The parasite's length 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 the small intestine.

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

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

How to prevent helminth infestation?

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

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