Human parasites can inhabit all organ systems. The vital activity of helminths can become a prerequisite for the development of cancer, and microscopic fungi and mites provoke 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. According to the canons of modern medicine, the concept of "parasite" does not apply to pre-nuclear (prokaryotic) organisms: bacteria and viruses. It is characterized by protozoa, fungi, worms, arthropods that live in the host's body, subsisting exclusively on it.
Microparasites
Human and animal organisms are a fertile environment for the life of microscopic fungi as well as protozoa. Indiscernible to the naked eye, they cause damage to the skin and internal organs.
Parasitic protozoa
An infection caused by a protozoan is called a protozoan. These diseases are widespread in tropical areas and in temperate latitudes. Approximately 50 species of protozoa parasitize human organs and tissues. They can become infected through sexual contact, food, or insect bites.
Giardiasis is widespread. Up to 40% of children and 10% of adults have this pathology. The lamblia's favorite habitat is the small intestine. The disease can be accompanied by digestive disorders, allergic reactions, although it is usually asymptomatic. The pathogen is transmitted by food, with unboiled water and contaminated food.
According to various sources, 30 to 50% of the world's population is infected with toxoplasmosis. Its pathogen often lives in the host's organism without clinical manifestations. Toxoplasma poses the greatest danger to pregnant women: it causes stillbirth or serious malformations. The infection occurs through contact with domestic mammals (cats, rabbits, rodents) and through the consumption of raw meat.
The most common sexually transmitted infection is the protozoan. This is trichomoniasis. More than 150 million people are infected worldwide each year. The manifestations of the disease are determined by the affected organs. 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 prostatitis, although more often the infection is asymptomatic.
In tropical regions, diseases such as malaria, leishmaniasis, Chagas disease, and sleeping sickness are widely known. Its causative agents are plasmodia, leishmania, and trypanosomes, respectively. Parasites are carried by blood-sucking insects: mosquitoes, tsetse flies, triatomeaceous bugs. By biting sick animals or people, they acquire and distribute the causative agents of these diseases.
Parasitic fungi
About 100 species of fungi are known to be quite dangerous to humans. Its optimal habitat is the warm and humid areas of the body, for example, the interdigital spaces. However, these organisms can also infect the skin and other areas of the human body.
Fungi of the Trichophyton, Microsporum, Epidermophyton species cause dermatomycosis: ringworm and pityriasis versicolor, lesions on the feet, scalp, rarely on the mucous membranes. The causative agents of these diseases can be transmitted to humans from sick animals or people. In severe cases, bacterial infections join dermatomycosis.
Mold fungi and their spores are no less harmful to humans. They cause diseases like this:
- penicellosis;
- mucosis;
- 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, parasitic fungi cause pneumonia and bronchial asthma. People with weakened immunity and chronic diseases are more susceptible to yeast infections.
Helminths
Parasitic worms' favorite habitat is the digestive tracts of humans and animals, where they feed on food, bile, and blood digested by the host. All helminths belong to the following classes:
- roundworms (nematodes);
- flatworms (tapeworms and trematodes).
Flat Parasitic Worms
Trematode eggs and larvae (flatworm flukes) often enter the human body with raw water, unwashed vegetables, meat and fish not sufficiently heat treated. Here's how:
- liver;
- Chinese
- giant;
- lanceolate trematodes;
- lucky cat.
Sometimes a person becomes infected by direct contact: larvae of tropical schistosome parasites pierce the skin of people who swim in fresh water and then enter the bloodstream, where they live and feedof erythrocytes.
Most flukes affect the liver, gallbladder and ducts of these organs and cause disease: flukes. The living environment of a pulmonary parasite is the muscles, the subcutaneous fatty tissue, the brain, but especially the lungs. The disease caused by this helminth is called paragonimiasis. The small metagonium trematode lives in the small intestine, leading to metagonimosis.
Trematodes are small in size - their flat, leaf-shaped body does not exceed 10 cm - however, the consequences of their permanence in 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 tapeworms (cestodes) can reach tens of meters in length. The main route of infection with cestodes is food. These helminths enter the human body with raw 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 the parenchymal organs (liver, lungs, spleen).
Of all tapeworms, the following are the most common:
- was bullish;
- echinococcus;
- wide ribbon;
- pork tapeworm;
- alveococcus.
Parasitic roundworms
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 life they can migrate to the muscles, lungs, heart and pharynx. The following nematodes are prevalent in the human population:
- pinworms;
- roundworm;
- toxocares;
- Trichinella;
- hookworms;
- Strongylids.
Roundworm eggs and larvae enter the human body through food and water. Nematodes, such as hookworms and strongylids themselves, invade the host's body. These helminths are found mainly in the tropics.
The omnipresent nematodes are pinworms, roundworms, and toxocaras. The former affect children most often and cause enterobiasis, the most common helminthiasis. Dogs are carriers of Toxocara, although these nematodes can also infect humans. Roundworms live in humans and are not dangerous to most animals, except for pigs.
Arthropod parasites
Parasitic cestodes, flukes, 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, typhus, and relapsing fever.
Lice drink human blood and parasitic mites live on human skin. The itching of scabies gnaws through the ducts, demodex lives in the hair follicles and the ducts of the sebaceous glands. The vital activity of these parasites causes allergies, accompanied by a rash, redness of the skin and itching.
The world we live in is developing rapidly, the standard of living is constantly increasing, and today it seems to many that parasitic diseases are the majority of the residents of third world countries. However, population migration leads to the spread of such pathologies beyond the natural foci. In this regard, it is important to remember the basic rules of hygiene, the observance of which will help to avoid infection.