Not everyone knows what is dangerous about the presence of helminths in the body, the types of worms and ways of infecting people. Some parasites can live in the human body without causing any disturbance. Up to 90% of adults and children do not even suspect that they are infected with worms. Helminths are of great medical importance, as they can be transmitted from person to person and cause dysfunction of internal organs.
The most common types of helminths
Human worms are parasitic worms that live in organs and live off their host. There are several hundred types of them. In some countries, laboratory tests can only detect some of them. The following types of worms are distinguished:
- nematodes (roundworms);
- cestodes (tapeworms);
- trematodes (flukes).
Distinguish between luminal and tissue parasites. The former are distinguished by the fact that they live in the lumen of a hollow organ (intestine, bile ducts). Tissue worms in humans live in the thickness of tissues. There are worms that belong to two groups at once. These are roundworms. Adults live in the lumen of the small intestine, and the larvae can infect the lungs and liver.
The classification of helminths includes the division of worms not only according to their habitat, but also according to the characteristics of the life cycle. Some parasites require intermediate hosts (molluscs, fish, animals) to complete development, in which the larvae mature. Such worms belong to the group of biohelminths. Some parasitic worms need to get into the external environment (water or soil). This is how geohelminths develop.
Contact types of helminthiases are distinguished separately. These include hymenolepiasis and enterobiasis. Infection with pinworms and dwarf tapeworms is possible upon contact with a patient. Distinguish between intestinal and extraintestinal worms. The first group includes pinworm, roundworm, tapeworm, whipworm. Other parasites (fasciola, fluke, echinococcus, trichinella, alveococcus) affect other organs.
Helminths from the nematode group
Various types of helminths are known. The most common are round worms (nematodes). They belong to the type of primordial worms. Human nematodes are arranged as follows:
- have a body that is not divided into segments;
- of various sizes;
- filamentary or spindle-shaped;
- have a skin-muscle sac and cuticle;
- have a digestive system in the form of a through tube;
- able to lay eggs.
Most often, the presence of these worms in humans is manifested by gastrointestinal disorders. The most common nematodes parasitizing in the human body are pinworms, roundworms, hookworms (nekators and hookworms) and whipworms. According to the WHO, more than 1 billion people suffer from enterobiasis. Young children are more likely to get sick.
A person can become infected with pinworms anywhere. This is due to the widespread distribution of the eggs of these helminths. Transmission factors include toys, household items, pens, pencils, unwashed food, dirty hands, railings on buses, telephones. Of all types of helminths, pinworms are detected most often.
These parasites reach a length of 1 cm and have a slender body with a sharp end. They attach to the intestines. Young children who attend kindergartens are more likely to get sick. Pinworms live in the human body for 1-2 months. A person can become infected not only with enterobiasis, but also with ascariasis. Often, these diseases are detected simultaneously. Roundworms are larger (20-40 cm).
These are geohelminths, the eggs of which develop and remain in the soil for a long time. The route of infection is oral. This happens when in contact with the ground, when drinking untreated water, eating vegetables and fruits contaminated with faeces. Very often worms such as whipworms are detected. This is the causative agent of trichocephalosis. They have a thin body that resembles hair. The back of the parasite is thickened.
These helminths reach a size of 55 cm. They parasitize in the colon. Up to 30% of the population are infected with hookworms. These are geohelminths, which are common mainly in countries with warm climates. They are otherwise called crooked heads. These worms parasitize only in humans. Their body length reaches 14 mm. Nekators can live up to 15 years, while hookworms can live up to 8 years.
Representatives of tapeworms
Doctors often have to deal with tapeworms. They are called cestodes. The peculiarity of this type of worms is that their body is divided into segments. This group includes various tapeworms (dwarf, bovine and pork), as well as a wide tapeworm. In children under 14 years of age, the causative agent of hymenolepiasis is often found. This is a dwarf tapeworm.
This type of helminth has the following distinctive features:
- up to 5 cm;
- parasitizes mainly in the intestines;
- has a head (scolex), a neck, a body (strobila), 4 suction cups and hooks;
- divided into segments;
- fully develops in the human body.
Along with pinworms, dwarf tapeworm belongs to contact helminths. The eggs of the parasite can be spread by insects (flies). There are varieties of cestodes that reach 20 m or more. A striking representative is the broad tapeworm. This is the causative agent of diphyllobothriasis. This worm belongs to the group of biohelminths.
To complete its life cycle and transform into an adult, it needs to enter the organism of intermediate hosts (fish and crustaceans). The peculiarity of this parasite is that its long stay in the human body leads to persistent anemia due to a lack of vitamin B12. Diphyllobothriasis often affects people who love fish. These parasites infect people living near freshwater bodies and fishing. The broad tapeworm is able to live in the human intestine for 20 years or more. Animals (cats, dogs, bears) can also act as the final owner.
Often, infection occurs with worms called echinococcus. They live in the human body in the form of larvae. People are intermediate hosts and at the same time a dead-end branch in the development of helminths. Infection occurs when eating meat from infected game or domestic animals, unwashed vegetables and fruits. Echinococci are single-chambered and multi-chambered.
The latter are called alveococci. These cestodes are more often localized in the liver and lungs, forming cysts. They are bubbles with a liquid substance and scolexes (heads) of the parasite. Massive liver damage can lead to tissue compression. If the cyst membrane ruptures, there is a risk of shock. There are other varieties of helminths from the cestode group: bovine and pork tapeworm. They are the causative agents of teniasis and teniarinchiasis.
Only doctors know what worms are. Flukes (trematodes) are very common. These include schistosomes, fascioles, and feline flukes. These types of helminths have the following features:
- small size;
- equipped with suction cups;
- leaf-shaped or rounded (with the exception of schistosomes).
The following groups of flukes are distinguished:
Most often, these parasites do not infect the intestines, but other organs. Infection with worms such as schistosomes can cause damage to the urinary tract (kidneys, bladder), liver, and other organs. More than 300 million people are infected with schistosomes. These are small (up to 2 cm) parasites with an elongated body. Men get sick more often than women.
Schistosomes affect the veins, kidneys, bladder, ureters, and abdominal organs. They feed on blood. Schistosomes are biohelminths. They develop in the body of freshwater molluscs. Their feature is the ability to actively leave the vessels and be excreted with metabolic products (urine and feces) into the environment. Schistosomiasis causes cystitis, anemia, lymphadenopathy, liver, kidney and genital injury.
Rare types of parasites in the human body include fasciola (hepatic and giant fluke). Some individuals reach a size of 10 cm. A person becomes infected through sick herbivores in an alimentary way when eating salads and greens growing next to stagnant bodies of water. Raw water can also be a transmission factor.
Fascioles are hermaphrodites. They affect the bile ducts, leading to the development of cholestasis and liver fibrosis. In severe cases, hepatitis or cholecystitis occurs. Among the endemic human helminths is the feline fluke. It causes opisthorchiasis. The reason is eating infected fish.
Not everyone knows what types of worms are transmitted through meat. This group includes such worms as bovine and pork tapeworm, echinococcus, Trichinella. A pathology such as trichinosis can lead to serious consequences. It is a disease caused by small round worms. Trichinella enter the human body through food.
It is dangerous to eat the following products:
- game (bear meat, wild boar);
- homemade sausage;
- homemade bacon;
- steaks and lightly rare meat;
It is not recommended to eat walrus, seal and nutria meat. The risk group includes hunters, tourists, livestock breeders and people who do not cook well or do not cook meat well enough. Trichinosis is characterized by a severe allergic reaction, edema and muscle damage. In difficult situations, a lethal outcome is possible.
Meat is a transmission factor for bovine and pork tapeworm. People become infected by eating pork or beef, which contains helminth Finns. This is an intermediate (larval) form of parasite development. Adult pork tapeworms reach 4 m in length, and bovine - 20 m.
The following risk factors for infection with teniasis and teniarinhoses are distinguished:
- lack of veterinary supervision;
- poor heat treatment of meat;
- cattle breeding (cows, pigs);
- unsanitary conditions;
- infection with cysticercus water.
Most often, only 1 adult tapeworm lives in the intestines of sick people. Despite this, the parasite can cause indigestion and intestinal obstruction. The presence of these helminths in humans can be detected by examining feces. A feature of the bovine tapeworm is that its segments during bowel emptying are able to crawl out and actively move.
The herbivores themselves become infected by eating grass contaminated with the feces of sick animals. Finns (cysticercus) are formed in the body of livestock (pigs and cows). When buying and cutting meat, they can be easily spotted. They are round and yellow in color. A person infected with a bovine tapeworm is not dangerous to others.
There are several types of worms that can be infected by eating insufficiently cooked or fried fish. The human body requires different products. Millions of people around the world consume freshwater fish, caviar and milk. They are at risk of contracting diphyllobothriasis and opisthorchiasis.
In some regions, the broad tapeworm and the cat fluke are endemic helminths. The reason is active fishing and fish infection. Opisthorchiasis infected up to 75% of the population. These parasites also infect animals (cats, foxes, dogs). Infection occurs when eating half-baked fish (carp, bream, roach, ide), infected with parasite larvae.
Risk factors include fast frying of infected raw materials, the use of lightly salted, dried or raw fish, caviar, kebabs. The mechanism of infection is alimentary. The feline fluke belongs to the group of flukes. This helminth does not exceed 2 cm in length. These worms cause stagnation of bile, inflammation of the pancreas, hepatitis, dyskinesia.
If untreated, the likelihood of developing cancer and cirrhosis increases. Fish can cause diphyllobothriasis. This is cestodosis caused by a wide tapeworm. Infection with these worms occurs when infected fish from freshwater bodies are consumed. The most dangerous are ruff, pike, perch, pike perch, burbot. All these are predatory fish. The second intermediate hosts of the tapeworm are crustaceans.
These helminths live in the small intestine of humans and some animals that feed on fish with tapeworm larvae. Unlike the causative agent of opisthorchiasis, this helminth affects the intestines, causing atrophy of the mucous layer. Anemia often develops. Diphillbotriosis mainly affects adults. The risk group includes people with fishermen in their family and lovers of dried and lightly salted fish.
Worms affecting the skin
There are helminths that affect the skin and soft tissues. This group includes rishta (the causative agent of dracunculiasis). It is a nematode up to 120 cm in size. It affects the subcutaneous tissue and intermuscular tissue. A person becomes infected by drinking dirty water or bathing. Parasites enter the intestines and then into the subcutaneous tissue.
When the helminth becomes sexually mature, it secretes special substances that corrode the skin. At this point, an ulcerative defect forms, through which the parasite displays the larvae. This happens when it comes into contact with water. Such patients experience severe itching. Rishta is more common in tropical countries. Cyclops (freshwater crustaceans) are intermediate hosts.
There are worms that can independently invade human skin upon contact with water. These include intestinal acne. The main infection mechanism is percutaneous. The larvae of the parasite damage the skin and rush into the blood. Risk factors for infection include walking on the ground with bare feet, swimming in muddy water bodies, and doing agricultural work.
How to get rid of different types of helminths
The doctor should treat patients after laboratory and instrumental studies. The antihelminthic drug is selected depending on the type of worms.
Many drugs kill and remove various types of helminths from the body. Almost always, doctors prescribe medications of a wide spectrum of action, since even after the detection of parasite eggs in the feces, it is very difficult to determine their species.
If an infectious person (in the case of hymenolepiasis or enterobiasis) lives with someone in the same apartment, then examination and treatment of these persons is required.
Each anthelmintic medicine has not only indications, but also contraindications.
Medication alone is not enough. Some types of parasitic worms require surgery. With echinococcosis, cysts are removed. The operation is also required in the presence of parasites in the heart and brain. Some helminths require compliance with sanitary and hygienic measures.
They are done after treatment and while taking medication. To get rid of pinworms, you need to change your underwear every day, wash it and iron it with an iron, wear tight swimming trunks, wash the floors and wipe all household items.
Thus, there are a large number of different parasitic worms that inhabit the human body.