Effect of parasites on a host organism can be different and depends on many factors: the species and systematic position of the parasite, its location in the host organism, size, metabolic rate, ability to move, excrete toxins etc the Action of the parasite even on the same host may depend on what stage of the parasite lives in its body and the condition of its owner. So, the same parasite that lives in the body of the child, may lead to delay physical and mental development, while in the adult it may not lead to the development of specific symptoms.
The deterioration of health
The most simple action of the parasite - mechanical stimulation of the host tissues in the process of its movement on the surface of the skin or inside the tissues and organs. Mechanical damage to tissues of mouth organs or organs of attachment of parasites may be accompanied by the introduction into the blood of the owner of the saliva, toxins, enzymes that cause hemolysis of red blood cells, as well as viruses, bacteria, protozoa and larvae of parasitic worms.
Skin lesions are usually accompanied by the formation of small wounds, papules or vesicles which cause a feeling of itching or pain. A number of parasites causes more severe tissue damage, sometimes leading even to complete destruction of individual organs (Fig. 18.10).
Parasites that live in the hollow organs, can cause obstruction, and parasites that live in the tissues of the internal environment, putting pressure on the organs often lead to their atrophy. The same parasite may have different effects depending on the organ in which it is located. Naturally, the parasite living in the subcutaneous adipose tissue might go unnoticed, whereas the same parasite, developing in a region of the medulla oblongata, almost inevitably leads to host death.
Long-term arrival of the parasite in the host organism, which is accompanied by chronic chemical and mechanical damage to the body often leads to cancer. This is especially true for many parasites from the class of parasitic flatworms.
Fig. 18.10. Manifestations of leishmaniasis caused by the parasite Leishmania bra-ziliensis and destruction of the nasal septum; - the complete destruction of the nose and palate
An important mechanism of action of parasites on a host organism - "the effect of withdrawal of food." It manifests itself in the first place the owner of the fastest-growing major parasites, such as tapeworms, as well as the simultaneous development of a large number of smaller forms, such as Ascaris. The children can often experience growth retardation, physical and mental development. In adults this may manifest in the loss of body weight. This is based on the original ecological treatment of obesity in humans: patients give capsules containing the infective ascaris eggs. Upon reaching clinical effect of parasites from the body of the patient are expelled.
Due to the fact that the specific needs of the parasites in different foods specific and differ from the needs of the owner, they are able to extract from the organism of certain substances in larger or smaller amounts. So, a tapeworm absorbs from the intestines of the host a large part of vitamin B12, thus breaking his blood, and astonished the red blood cells, absorbs plasma from the blood up to 100 times more amino acids and 8 times more orós acid than whole molecule of the hormone.
Almost all parasites, highlighting the products of its life in an environment is a host organism that cause allergies. Therefore, in most diseases caused by parasites, against the background of their specific symptoms is almost always revealed signs characteristic of various kinds of allergic conditions: eosinophilia, pruritus, hives, facial swelling, bronchospasm, and others. that is why the increase in the number of eosinophils in the blood of the patient under mysterious causes, and diagnosis - a symptom in which it is necessary to survey for the presence of parasites in the body of the patient.
There are exceptions to this rule: Schistosoma haematobium has, or blood flat worm, getting into the human body, reduces the probability of he different kinds of allergic conditions. This unusual phenomenon has been extensively studied.
Parasites often modify the behavior of their hosts in such a way that infected them the next hosts dramatically easier. This increases the probability of successful completion of the developmental cycle of the parasite and in the next generations.
Not all of the examples presently explained. Some are known as empirical facts. However, they imply the necessity of the physician's work with patients with diseases caused by parasites, and make the necessary further study of the factors of human susceptibility to parasites.