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 more complex organization. For convenience, the article is presented in a table with the main characteristics.
Characteristically
The simplest include organisms with primitive organization, which are fused into the Protozoan type. There are more than 15, 000 species, and some of them lead a parasitic lifestyle in the human body. They are all characterized by small size, can only be seen under a microscope, and are impossible to spot with the naked eye.
Many of the simplest parasites have an extremely primitive structure. When they enter the body of the host, they begin to reproduce. Sometimes this happens by dividing into two halves, and sometimes by multiple divisions. In the latter case, the disease develops rapidly, symptoms appear quickly, and can sometimes even cause death.
Properties of biology
The organism of protozoan human 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 cysts if environmental conditions become unfavorable. Therefore, they are able to remain sustainable for a long time, remaining immobile and without nutrients. As soon as the condition normalizes, the cyst shell is destroyed and the microorganism continues to function normally. Encystation 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 humans are intermediate or final hosts.
Main types
Protozoan parasites cause many diseases and parasitize various organs. For convenience, they are shown in the table.
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| Name |
Infected body parts |
Mode of infection |
Symptoms |
|---|
| Balantidia |
lower part of the intestine |
Consumption of uncooked pork or water with cysts |
Balantidia is often accompanied by diarrhea. White mucus and bloody discharge appear in the feces. The mucous membrane of the large intestine ulcerates and in such cases increased bleeding may occur. As the disease progresses, the person becomes exhausted, and in rare cases it can lead to death. |
| amoeba from the mouth |
Oral cavity, right pockets, dental plaque |
A person becomes infected by kissing the 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. May cause periodontal disease. |
| dysenteric amoeba |
It penetrates the bloodstream into the lungs, liver, heart, genitals, kidneys. It settles in the intestinal lumen |
Ingestion with food or water |
In some cases, the disease is asymptomatic. If the dysenteric amoeba attacks the intestinal walls, then the pathogenic stage begins. It is characterized by colitis, tissue necrosis, liver damage, abscesses may occur. Very severe consequences cause metastases in the brain and other organs. Possible fatal outcome. Sometimes the disease has a recurrent course. Self-healing is rare |
| Intestinal Giardia |
Duodenum and bile ducts. |
oral route |
Giardia sticks to the epithelium of the mucous membrane and impairs the absorption of nutrients. Inflammation of the mucous membranes and persistent diarrhea develop. If the infection affects the bile ducts, yellowing of the skin appears. Some people develop immunity to intestinal Giardia, especially in countries with tropical climates. |
| Trichomonas vaginalis |
In women - on the mucous membrane of the vagina, in men - in the epidermis of the prostate and in the urethra |
During sexual intercourse, as well as during childbirth from mother to child |
Trichomoniasis is manifested by foamy discharge, itching and burning on the mucous membrane of the genital organs, pain during sex, the appearance of bloody discharge from the urethra, etc. A complication of trichomoniasis is inflammation of the vulva due to the action of protozoa, cystitis, prostatitis and infertility |
| Trypanosoma brussei |
Cerebrospinal fluid and brain |
After being bitten by a ceca fly, which is a middle host |
It starts with fever and swollen lymph nodes, continues with apathy, irresistible desire to sleep, muscle paralysis and exhaustion. If left untreated, coma and death result. |
| Skin leishmaniasis |
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 brownish dense nodule appears at the site of the insect bite. It increases, and then a purulent ulcer opens in its place. The disease lasts up to several years, and then the final scarring of the wounds occurs. Complications can be disorders of the heart, kidneys and adrenal glands. |
| Toxoplasma |
Infected domestic animals, mostly cats, sometimes get an infection when 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, liver enlargement, headaches, vomiting, convulsions. It often has a chronic course with increased fatigue and eye damage. It rarely occurs in latent form |
| Isospora |
From an infected person by fecal-oral transmission |
small intestinal epithelium |
The incubation period lasts about 10 days. Then the body temperature rises, vomiting and diarrhea occur. The disease is acute for a week or two, and then recovery occurs |
| Crypto sporidia |
oral route |
Intestinal epithelial tissues |
Incubation lasts about a week, then diarrhea begins, possibly with the appearance of spots. Stomach pain may occur, fever may occur, and signs of dehydration may occur. In case of insufficient immune status of the patient, the infection can also affect other organs: lungs, pancreas, stomach, etc. |
Are worms the simplest
Sometimes you can hear the phrase that the patient is infected with the simplest worms. It must be understood that protozoa are exclusively single-celled microorganisms, which in extreme cases organize colonies. 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 complex: they have differentiated organs that perform special physiological functions. Therefore, it is fundamentally wrong to classify worms as protozoa.
Helminths are sometimes called the simplest parasites in relation to insects: bed bugs, lice, etc. , Since the latter are much higher on the evolutionary scale. In this interpretation, the name worm is allowed as a protozoan.
