Human parasites are represented by different groups, one of which is the 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 characteristics.
Characteristic
The simplest include organisms with a primitive organization, which are combined in the Protozoa phylum. It has more than 15 thousand species, and some of them lead a parasitic lifestyle on the human body. All of them are characterized by their small size, they can only be seen under 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 other times by multiple splitting. In the latter case, the disease develops rapidly, the symptoms appear quickly, sometimes capable of even causing the death of a person.
characteristics 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 may be one or more.
Protozoa have the ability to form a cyst if environmental conditions become unfavourable. Due to this, they are able to remain viable for a long time, remaining immobile and without nutrients. As soon as conditions return to normal, the cyst shell is destroyed and the microorganism continues its normal function. Encystment also allows parasites to successfully spread from one organism to another.
All protozoa are divided into several categories based on anatomy, mode of movement, and other characteristics:
- flagella;
- sarcode
- sporozoa
- ciliates.
Within each group, there are species for which humans are the intermediate or definitive host.
main types
Protozoa-type parasites cause many diseases and parasitize in different organs. For convenience, they are presented in the table.
| Name | infected body parts | infection method | 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 becomes ulcerated and, in such cases, bleeding may increase. With the progress of the disease, exhaustion of a person occurs, in rare cases it can lead to death. |
| mouth amoeba | Oral cavity, gum 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 erythrocytes. It can cause periodontal disease. |
| dysenteric amoeba | Through the bloodstream it penetrates into the lungs, liver, heart, genitals, kidneys. 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, the pathogenic stage begins. It is characterized by colitis, tissue necrosis, liver damage, abscesses may appear. Very serious consequences cause metastases in the brain and other organs. Possible fatal outcome. Sometimes the disease takes a recurrent course. Self-healing rarely occurs |
| intestinal giardia | Duodenum and bile ducts. | orally | Giardia adheres to the mucosal epithelium and impairs nutrient absorption. Inflammation of the mucosa and constant diarrhea develop. If the infection covers the bile ducts, yellowing of the skin appears. Some people develop immunity to intestinal Giardia, especially in countries with a tropical climate. |
| trichomonas vaginalis | In women, in the vaginal mucosa, 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 of the mucous membrane of the genital organs, pain during sexual intercourse, 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 begins with a fever and swollen lymph nodes, continues with apathy, an irresistible desire to sleep, muscle paralysis, and exhaustion. If left untreated, coma and death occur. |
| Cutaneous 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 dense nodule of brown color 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 healing of the wounds occurs. Complications can be disorders of the heart, kidneys, and adrenal glands. |
| toxoplasma | Infected domestic animals, mainly cats, sometimes infection occurs by ingesting food containing protozoa | liver, heart, eyes, brain | In congenital form: multiple pathologies of fetal development, death in infancy, mental retardation, multiple infections. Acquired toxoplasmosis causes high fever, enlarged liver, headaches, vomiting, seizures. It often takes a chronic course with increased fatigue and eye damage. It rarely occurs latently. |
| isospore | 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. The disease is acute for a week or two, then recovery occurs. |
| crypto sporidia | orally | epithelial tissues of the intestine | Incubation lasts about a week, then diarrhea begins, possibly with inclusions of spots. The stomach may hurt, fever appears, signs of dehydration are possible. With an insufficient immune status of the patient, the infection can 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 should be understood that protozoa are exclusively unicellular microorganisms, in extreme cases, organizing colonies. But they are never multicellular like worms and helminths.
In protozoa, all processes occur 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.
Sometimes helminths are called the simplest parasites compared to insects - bedbugs, lice, etc. , since the latter are much higher up the evolutionary scale. In this interpretation, the name of worms as protozoa is allowed.