Human parasites are represented by different groups, one of which is protozoa. They are capable of causing diseases of varying severity, and these microorganisms are not as easy to diagnose as groups with a more complex organization. For convenience, in the article they are presented in a table with the main features.
Feature
The simplest include organisms with a primitive organization, which are combined in the phylum Protozoa. It has more than 15, 000 species, and some of them lead a parasitic lifestyle in the human body. All of them are characterized by small sizes, they can be seen only with a microscope and it is impossible to notice them with the naked eye.
Many of the simplest parasites have an extremely primitive structure. Once in the host's body, they begin to multiply. Sometimes this happens by splitting into two halves and sometimes by multiple division. In the latter case, the disease develops quickly, symptoms appear quickly, sometimes even capable of causing the death of a person.
Features of biology
The organism of human protozoan parasites consists of two main parts: the nucleus and the cytoplasm, in which all other organelles are located. The core can be one or more.
Protozoa have the ability to form a cyst if environmental conditions become unfavorable. Because of this, they are able to remain viable for a long time, remaining immobile and lacking nutrients. As soon as conditions return to normal, the cyst shell is destroyed and the microorganism continues its normal functioning. Encystment also allows parasites to successfully spread from organism to organism.
All protozoa are divided into several categories depending on anatomy, mode of movement and other characteristics:
- flagella;
- sarcode
- sporozoans
- ciliates.
Within each group, there are species for which man is the intermediate or definitive host.
main types
Protozoan parasites cause many diseases and parasitize in different organs. For convenience, they are presented in the table.
| Name | Infected body parts | method of infection | Symptoms |
|---|---|---|---|
| balantidia | lower intestines | Eating raw pork or water with cysts | Balantidiasis is often accompanied by diarrhea. White mucus and bloody discharge appear in the stool. The colonic mucosa ulcerates and, in these cases, bleeding may increase. With the progress of the disease, exhaustion of a person occurs, in rare cases it can lead to death. |
| amoeba mouth | Oral cavity, gingival pockets, dental plaque | A person becomes infected by kissing a carrier, using dirty dishes, and eating contaminated food. | It rarely affects people who do not have pathological lesions in the oral cavity. In inflammation, the oral amoeba feeds on epithelium, microbes, leukocytes, and erythrocyte cells. It can cause periodontal disease. |
| dysenteric amoeba | Through the blood stream it penetrates the lungs, liver, heart, genitals, kidneys. Attaches to the intestinal lumen | Ingestion with food or water | In some cases, the disease is asymptomatic. If the dysenteric amoeba attacks the intestinal walls, the pathogenic stage begins. It is characterized by colitis, tissue necrosis, liver damage, abscesses may appear. Very serious consequences cause metastases to the brain and other organs. Possible fatal outcome. Sometimes the disease has a recurrent course. Self-healing rarely occurs |
| Intestinal Giardia | Duodenum and bile ducts. | oral route | Giardia adheres to the mucosal epithelium and impairs nutrient absorption. Mucosal inflammation and constant diarrhea develop. If the infection covers the bile ducts, the skin will turn yellow. Some people develop immunity to intestinal Giardia, especially in countries with a tropical climate. |
| Trichomonas vaginalis | In women - on the vaginal mucosa, in men - on the prostate epidermis and urethra | During intercourse as well as during childbirth from mother to child | Trichomoniasis is manifested by foamy secretion, itching and burning in the mucous membrane of Organs genitals, pain during sex, the appearance of bloody discharge from the urethra, etc. A complication of trichomoniasis is inflammation of the vulva due to protozoan activity, cystitis, prostatitis and infertility. |
| Trypanosoma brussei | Cerebrospinal fluid and the brain | After being bitten by a tsetse fly, which is an intermediate host | It starts with fever and swollen lymph nodes, continues with listlessness, an overwhelming desire to sleep, muscle paralysis and exhaustion. If untreated, coma and death ensue. |
| Cutaneous Leishmania | Contact with a sick person or animal | On the skin, most often on the face or hands | The incubation period lasts from 2 months to 5 years, after which a dense brownish nodule appears at the site of the insect bite. It increases, and then a purulent ulcer opens in its place. The disease lasts for several years and then the final healing of the wounds occurs. Complications can be disorders of the heart, kidneys and adrenal glands. |
| toxoplasma | Infected domestic animals, particularly cats, sometimes become infected by eating food with protozoa | Liver, heart, eyes, brain | In the congenital form - multiple pathologies of fetal development, death in childhood, mental retardation, multiple infections. Acquired toxoplasmosis causes high fever, enlarged liver, headaches, vomiting, convulsions. It often takes a chronic course with increased fatigue and eye damage. Rarely occurs latently |
| isospora | From an infected person with fecal-oral transmission | small intestine epithelium | The incubation period lasts about 10 days. Then the body temperature rises, vomiting and diarrhea appear. Illness is acute for a week or two, then recovery occurs |
| Cryptosporidia | oral route | Intestinal epithelial tissues | Incubation lasts about a week, then diarrhea begins, possibly with spotty inclusions. The stomach may ache, fever appears, signs of dehydration are possible. With the patient's insufficient immune status, the infection can affect other organs: lungs, pancreas, stomach, etc. |
Worms are the simplest
Sometimes you can hear the phrase that the patient is infected with the simplest worms. It should be understood that protozoa are exclusively unicellular microorganisms, in extreme cases, colonies in organization. But they are never multicellular like worms and helminths.
In protozoa, all processes take place within the cell cytoplasm and cell nuclei, while in worms, the anatomical organization is much more complicated: they have differentiated organs that perform special physiological functions. Therefore, it is fundamentally wrong to classify worms as protozoa.
Helminths are sometimes called simpler parasites compared to insects: bed bugs, lice, etc. , as the latter are much higher up the evolutionary ladder. In this interpretation, the name of worms is allowed as protozoan.