Human parasites can reside in all organ systems. The vital activity of helminths can become a prerequisite for the development of cancer, and fungi and microscopic mites lead to allergies.
The human body can be inhabited by at least 300 parasitic species, including representatives of bacteria, viruses, protozoa, microscopic fungi, helminths (parasitic worms), individual arthropods. These organisms not only consume nutrients assimilated by the host, but also poison it with the products of their vital activity. In accordance with the canons of modern medicine, the concept of "parasite" does not apply to prokaryotic organisms: bacteria and viruses. Characterizes protozoa, fungi, worms, arthropods that live in the body of the host, living exclusively in it.
Microparasites
Human and animal organisms are a fertile environment for the life of microscopic fungi as well as protozoa. Indistinguishable to the eye, they cause damage to the skin and internal organs.
Parasitic protozoa
An infection caused by a protozoan is called a protozoan. Such diseases are prevalent in tropical areas as well as in mild latitudes. About 50 species of protozoa parasitize human organs and tissues. They can be infected through sexual contact, food or insect bites.
Giardiasis is very common. Up to 40% of children and 10% of adults have this pathology. The preferred habitat for lamblia is the small intestine. The disease can be associated with digestive disorders, allergic reactions, although it is often asymptomatic. The pathogen is transmitted by food - with undigested water and contaminated food.
According to various sources, 30 to 50% of the world's population are infected with toxoplasmosis. Its pathogen often lives in the host organism without any clinical manifestation. Toxoplasma poses the greatest risk to pregnant women: it causes intrauterine fetal death or severe malformations. Infection occurs through contact with domestic mammals (cats, rabbits, rodents) and consumption of uncooked meat.
The most common sexually transmitted infection is protozoal. This is trichomoniasis. More than 150 million people are infected worldwide each year. Manifestations of the disease are determined by the organs affected. In women, Trichomonas lives in the vagina, causing inflammation, accompanied by urethritis. In men, the protozoan affects the prostate gland, the seminal vesicles, in severe cases leading to the prostate, although most often the infection is asymptomatic.
In tropical regions, diseases such as malaria, leishmaniasis, Chagas disease and sleep sickness are widely known. Their causative agents are plasmodia, leishmaniasis and trypanosomiasis, respectively. Parasites are transmitted by blood-sucking insects: mosquitoes, cetse flies, triatomaceous bugs. By biting sick animals or people, they acquire and disperse the causative agents of these diseases.
Parasitic fungi
About 100 species of fungi are known to be quite dangerous to humans. Their optimal habitat is the warm and humid area of the body, for example, interdigital spaces. However, these organisms can also infect the skin and other areas of the human body.
Fungi of the species Trichophyton, Microsporum, Epidermophyton cause dermatomycosis: ringworm and colored pityriasis, lesions of the feet, head, rarely of the mucous membranes. The causative agents of these diseases can be transmitted to humans from animals or sick people. In severe cases, bacterial infections join dermatomycosis.
Mold fungi and their spores are no less harmful to humans. They cause diseases like this:
- penicelosis;
- mucosa;
- aspergillosis.
These pathologies are characterized by inflammation of all parts of the respiratory tract without exception, otitis media and various allergic reactions. In severe cases, the parasitic fungus causes pneumonia as well as bronchial asthma. People with weakened immunity and chronic diseases are more susceptible to fungal infections.
Helminths
The preferred habitat for parasitic worms is the digestive tract of humans and animals, in which they feed on the host's digested food, bile and blood. All helminths belong to the following classes:
- roundworms (nematodes);
- flatworms (strips and flakes).
Flatworms
Eggs and larvae of trematodes (flatworm flukes) most often enter the human body with raw water, unwashed vegetables, meat and fish not properly treated in heat. Thus:
hepatic;
Sometimes a person becomes infected through direct contact: the larvae of tropical schistosome parasites pierce the skin of people who swim in fresh water, then enter the bloodstream, where they live and feed on erythrocytes.
Most trematodes affect the liver, gallbladder and ducts of these organs, causing disease - trematodes. The living environment of a pulmonary eruption is muscle, subcutaneous adipose tissue, brain, but above all, lungs. The disease caused by this helminth is called paragonimiasis. The small trematode metagonium lives in the small intestine, leading to metagonism.
Hair is small in size - their flat, leaf-shaped body does not exceed 10 cm - however, the consequences of their stay on the body of animals and humans are fatal. Long-term parasitism of these helminths can lead to the development of cancer, cirrhosis and gallstone disease.
Unlike trematodes, the body of worms (cestodes) can reach tens of meters in length. The main route of infection with cestodes is food. These helminths enter the human body with immature meat and fish. The main environment for the development of cestodes is the small intestine, in which adult worms live, while the larval forms live in parenchymal organs (liver, lungs, spleen).
Of all the tapeworms, the following are the most common:
- bullish ribbon;
- ekinokoku;
- wide ribbon;
- pork ribbon;
- alveokoku.
Round parasitic worms
Diseases caused by parasitic roundworms - nematodes - rank first among all helminthiases in terms of frequency of development. The habitat of most adult parasites is the intestines, but at certain stages of their lives they can migrate to the muscles, lungs, heart and pharynx. In the human population, the following nematodes are prevalent:
- peg worms;
- round worm;
- toxicos;
- Trichinella;
- fat worms;
- Strongness.
Eggs and larvae of roundworms enter the human body through food and water. Nematodes themselves, such as fat worms and fortilids invade the host body. These helminths are found mainly in the tropics.
ubiquitous nematodes are worm worms, roundworms and toxocarp. The former most often affect children, causing enterobiasis - the most common helminthiasis. Dogs are carriers of Toxocara, although these nematodes can infect humans as well. Roundworms live in humans and are not dangerous to most animals, except pigs.
Arthropod parasites
Parasitic cestodes, trematodes and nematodes are adapted to live in the internal organs of their hosts. In contrast, most parasitic arthropods live on the surface of the body. Most often, a person becomes infected with lice and mites, the causative agents of demodicosis and scabies. These parasites are dangerous because they can carry pathogenic bacteria and rickettsia that cause Volyn fever, typhoid and relapsing fever.
Lice drink human blood and parasitic mites live on human skin. The scabies itches through the passages in it, the demodex lives in the hair follicles and sebaceous gland ducts. The vital activity of these parasites leads to allergies, accompanied by rash, skin rash and itching.
The world we live in is evolving rapidly, the standard of living is constantly rising and today for many it seems that parasitic diseases are the majority of the inhabitants of third world countries. However, population migration leads to the spread of such pathologies beyond natural foci. In this regard, it is important to remember the basic rules of hygiene, observance of which will help avoid infection.