Types of worms in humans and methods of infection with them

Worms are representatives of the lower worms that live in the human body. A disease associated with human infection by various types of worms is called helminthiasis. This disease is not uncommon and occurs among certain segments of the population. Children are susceptible to pinworm infection, hunters - trichinella, fishermen and lovers of Japanese cuisine (raw fish in the form of sushi) suffer from diphyllobothriosis.

Many diseases, paradoxically, can occur in the human body due to helminthiasis. Today, the theory of the connection between cancer and parasitic infections is one of the most relevant. In the presence of helminthiasis, symptoms do not always appear, and if, nevertheless, patients with this disease experience any unpleasant and uncomfortable sensations, they are perceived as signs of other diseases. The patient had been treated for years for pancreatitis, gastritis or colitis without suspecting that the cause of his diseases was helminthiasis.

How does the infection occur?

Worms bring many problems to people

Helminth infection occurs as follows:

  • Through unwashed hands
  • In contact with soil
  • After insect bites
  • Because of dirty hands
  • When eating raw meat and fish
  • After eating unwashed fruits and vegetables
  • After contact with an animal
  • After contact with infected people

Mature parasite eggs can be found in soil, water and food (raw and lightly cooked meat or fish). Rare cases of the disease occur due to insect bites. The mechanism of infection with helminthiasis is oral-fecal. A person ingests parasite eggs with food and water. There are also contact and household methods of infection. They occur when hands have not been thoroughly washed after contact with soil or sand.

Vegetables and berries growing in the ground that are not sufficiently washed are also a source of worm infection. Children who play with farm and domestic animals are at risk of getting worms. Pets that walk freely on the streets can bring helminth eggs into the house. Flies and other insects, after contact with animal feces landing on food, can easily transfer helminth eggs. Surprisingly, person-to-person transmission is also possible. This happens in the following way: female pinworms can crawl out of the intestines and lay eggs directly on the underwear, causing severe itching. A person, after scratching an itchy place, can come into contact with other toilet and household items. These items fall into the hands of other family members and then become infected.

Contagion through water is also possible. Many parasite eggs easily fall into open tanks and wells. Drinking unboiled well water is extremely dangerous.

Types of helminthiasis

Helminthiasis differ in the method of penetration into the human body:

  1. Biohelminths
  2. Geohelminths
  3. Contagious

Biohelminths are transmitted to humans through contact with animals. Geohelminths can be infected through the soil. Contagious occurs through contact with an infected person. The disease manifests itself differently depending on the method of infection, the number of worms and the degree of their adaptation in each human organ.

Stages of helminthiasis

Adult and helminth egg

The most destructive effect on the body is not caused by adults, but by their larvae. Adults have already chosen a cozy place for themselves in the human body, and the larva travels through the organs and leaves behind lesions. The most common habitat for parasites is the gastrointestinal tract. Different types of parasites prefer different habitats. Thus, roundworms are found in the small intestine, and pinworms settle in the large intestine and lower parts of the small intestine. According to the habitat of the parasites, helminth infections are:

  • Translucent
  • Cloth

The luminal ones are located in the lumens of the genital organs, and the tissue ones are located inside the tissues. Depending on their growth, parasites can change their habitat, passing from a luminal form to a tissue form. Helminthiasis develops in two stages:

  1. Spicy
  2. Chronic

The acute stage lasts from a week to a month, and the chronic stage lasts until healing. The acute stage begins with the introduction of the egg and continues with the maturation and growth of the parasite. The disease manifests itself as allergic reactions to a foreign organism. During the chronic stage of the disease, various reactions of the body occur. During this period, the parasite moves around the body in search of shelter. The disease is accompanied by disturbances in the functioning of organs and systems in the human body. Integrating into the immune system of the human body, parasites consume substances necessary for their growth and development. This leads to metabolic disorders, disorders of the digestive system and difficult absorption of vitamins and minerals.

In addition to this harm, parasites expel their waste products into the human body, poisoning the body, which leads to intestinal disorders, reduced immunity and the development of bacterial infections. Parasites contribute to the risk of developing cancer. This is due to the negative impact on the immune system and the stimulation of cell division. Often, the patient is examined by many specialists who discover a bunch of diseases. And in this case, all specialists can be replaced by a single doctor - a parasitologist.

Classification of helminths

Roundworms are quite common in the human intestine.

Types of worms in humans:

  1. Flatworms
  2. Roundworms

Flatworms include:

  • Trematodes (opisthorchiasis, schistosomes, paragonimus)
  • Cestodes (broad tapeworm, pig tapeworm, echinococcus, alveococcus)
  • Roundworms or nematodes:
    • Pinworm
    • Ascaris
    • Hookworm
    • Trichinella

This classification of helminths is presented in the medical literature. To successfully solve a problem such as helminthiasis, it is necessary to discover in-depth characteristics of the structure and life cycle of parasites.


Another name for trematodes is flukes. These parasites are flat-leaf or spear-shaped with two shoots. One sucker is in the mouth, and the second, which serves for attachment, is in the peritoneum. All flukes enter the body through an intermediate host. Most of these parasites are hermaphrodites.


This is a moth - a worm up to 1. 3 cm long with two suckers. Opisthorchosis is a hermaphrodite that parasitizes the liver, gall bladder and pancreas of humans and some carnivores (foxes, dogs, cats). The eggs of opisthorchiasis are passed out of the human or animal body with faeces. When these eggs enter a body of water, they are ingested by freshwater molluscs, where they hatch and develop into larvae. The process of development and maturation of the larvae lasts two months. The larvae then crawl out of the mollusk and penetrate the skin of the carp. After six weeks, the larvae turn into full-fledged mature parasites. Opisthorchiasis enters the body of an animal or a person after eating infected fish. This worm can live in a living organism for up to 20 years. Symptoms of opisthorchosis:

  1. Alergy
  2. Weakness
  3. Headache
  4. dizziness
  5. depression
  6. Loss of consciousness

Damage caused to the body by opisthorchiasis:

  • Poisoning by waste products from parasites
  • Damage to liver tissue
  • Gallbladder damage
  • Impaired outflow of bile
  • Inflammation of the pancreas
  • Secretory dysfunction
  • Decreased gastric motility
  • Thickening of the walls of some organs, the appearance of tumors as a result.

The chronic course of the disease is characterized by:

  • Heaviness after eating
  • pain
  • vomiting
  • nausea

Prevention of infection: To avoid contracting opisthorchiasis, you should not eat raw fish. Larvae die during heat treatment of products. Dried fish can only be eaten if it has been previously salted. Also, the larvae die when the fish is frozen for a long time.


Garlic is an effective anthelmintic

These parasites are of different sexes, needle-like, 0. 4 to 2. 6 cm long. Females are longer than males and larger, producing 3000 eggs per day. The method of reproduction is the same as that of the previous type of parasite, by freshwater molluscs. The larva enters the human body through the skin and mucous membranes while swimming in a freshwater body. It can also enter the body of a person who accidentally swallows water while swimming. After a day of penetration, the larva turns into an adult and enters the peripheral veins, through which it is sent to the lungs and venous vessels. There the schistosoma reaches sexual maturity.

Schistosoma lays eggs in the intestines, mucous membranes and bladder. The eggs are then excreted from the human body in urine or faeces and start their developmental journey all over again. Schistosoma lives in the human body for several decades, causing harm and infecting new individuals. The problems that arise when infected with schistosomes are caused to the human body not by adults, but by their eggs. Only half of the eggs are released from the body, the rest accumulate in the organs. The eggs of this parasite have spines that damage a person's internal organs, often causing ulcers in the infected person. Patients with schistosomiasis experience the following symptoms:

  • Appetite disorder
  • anemia
  • Enlarged liver
  • Altered spleen
  • Decreased intestinal motility
  • Stomach pains
  • constipation
  • diarrhea
  • Losing weight
  • Intestinal bleeding
  • Pain during urination
  • Allergies
  • Weakness

When the genitourinary system is infected, patients experience:

  1. Menstrual irregularities and miscarriages in women
  2. Impotence and incomplete ejaculation in men

If the eggs enter the central nervous system:

  • Acute cerebral schistosomiasis
  • Chronic brain damage
  • Death

Infected children have delayed growth and development and poor school performance. Disease prevention includes avoiding swimming and walking barefoot in tropical waters.


Prevention of worm infection - hand washing

Paragonimus is a 1 cm long lung fluke with an egg-shaped body and red spines. This parasite multiplies in the lungs of animals and enters the human body by eating crabs and freshwater crabs. The parasite affects the respiratory system. Patients with paragonimosis are characterized by allergic reactions and reduced immunity. Symptoms:

  • rise in temperature
  • cough
  • Separation of sputum from the lungs when coughing
  • dyspnea
  • In severe cases, the sputum contains blood and parasite eggs
  • Wheezing is clearly heard in the patient's lungs

Prevention: Avoid eating raw crabs and crayfish.


Representatives of cestodes are tapeworms of different lengths. Some parasites reach gigantic sizes. On the head of these parasites there are shoots, hooks or suction slits. Parasites need these devices to adhere to the intestinal walls. Cestodes affect the whole human body, they are most dangerous for children, who quickly develop anemia.


These parasites reach a length of up to 5 cm and are the causative agents of the Echinococcus disease. The multichamber representative of this type of worms is the cause of a disease such as alveococcosis. The disease is transmitted by cattle and domestic animals. When these animals are cared for, parasite eggs fall from their fur onto people's hands. When parasites enter a person's intestines, they burrow into the mucosa. As the parasite matures, it develops 4 parts, the last of which is filled with eggs. These areas break off and spread throughout the body, infecting it. The fourth section scatters eggs all over the body.

The patient's infected organ is enlarged, for example, the liver. Suppuration may form. An enlarged organ may even rupture the abdominal cavity. And this can lead to serious sepsis of the body and even death. Symptoms:

  • Weakness
  • dizziness
  • Allergic reactions to parasite waste products.

Echinococcus affects:

  1. brain
  2. Spinal cord
  3. eyes
  4. Thyroid gland
  5. Liver
  6. Lungs
  7. Uterus

This parasite can provoke the formation of tumors, including malignant ones. The most unpleasant thing is that the treatment of this disease is possible only with surgery. Prevention: personal hygiene when in contact with animals.


These worms with an elongated body, round or cylindrical, parasitize most often in the body of children. These roundworms include pinworms, roundworms and hookworms.


Giardia are parasites too!

These are small white worms. The length of the female is 1 cm, the male is 0. 5 cm. These parasites have a pointed tail, which is why they were called pinworms. The habitat of sedges is the human intestine. The front end of the parasite has a suction cup, with the help of which the pincers penetrate the intestine, and the sharp end hangs in the lumen and damages the walls. This disease is called enterobiosis. You can get infected from a person through dirty hands. The disease is observed in children of preschool age attending kindergarten. A symptom of pinworm infection is itching near the anus. More often, itching is felt at night, when the female lays eggs, releasing a special substance. Symptoms:

  1. itching
  2. diarrhea
  3. Stomach pains
  4. Headache
  5. Lack of appetite

Prevention: hand washing.


These worms are the largest. The length of the female is up to 0. 5 m. The female lays 200 thousand eggs per year, regardless of the male. The mechanism of infection is fecal-oral. Ascaris eggs enter the human body along with unwashed vegetables and fruits, through dirty hands. The larva, entering the intestine, is selected from the shell and penetrates the intestinal walls as it migrates through the intestinal veins to the liver, through the hepatic veins into the heart, through the pulmonary arteries into the bronchi, then into the trachea and into the mouth. Part of the larvae die in the open air, the rest are swallowed back. Symptoms:

  • nausea
  • Vomiting
  • Jaundice
  • Pancreatitis
  • Frequent acute respiratory infections
  • Bronchitis
  • Pneumonia


  • Washing hands
  • Washing vegetables and fruits
  • Maintaining personal hygiene
  • Protect food from flies, cockroaches and other vectors.

In conclusion, we can say that the cause of the disease is not always bacteria and viruses that have entered the body. Parasites can cause enormous harm to human health. If vague symptoms appear, the possibility of a parasite entering the body should not be excluded, the patient should visit a parasitologist.