Protozoan parasites in humans are the causative agents of protozoan infections (or protozooses). These diseases are contagious and threaten serious complications and consequences. Therefore, protozoosis requires timely diagnosis, accurate identification of the pathogen, and appropriate treatment.
What are protozoan parasites?
This is a group of single-celled microorganisms that cannot independently generate nutrients. In the process of life, they make use of other creatures, causing serious illnesses. The most common human protozoan parasites are listed below:
- flagella - giardia, leishmania, trichomonas, trypanosome;
- sarcodal - dysenteric amoeba;
- ciliates - bursaria, balantidia;
- Sporozoa: malarial plasmodium, coccidia, piroplasms.
trypanosome
The simplest parasite whose life cycle takes place in the body of ungulates (antelopes) or an infected person. The carriers are tsetse flies, which, when bitten by a person, inject saliva with protozoa into their skin.
In a note!
For the development of the disease (African trypanosomiasis or sleeping sickness), the introduction of about 400 trypanosomes is necessary. With one tsetse fly bite, up to half a million individuals of the parasite fall out.
Characteristics of parasitism and disease:
- trypanosomes initially circulate in the bloodstream of an infected person, causing trypanids in the skin (swelling of the face, eyelids), fever with a temperature of up to 40°C, swollen lymph nodes;
- single-celled parasites then migrate to the cerebrospinal fluid, causing drowsiness, iridocyclitis, chronic fatigue, lethargy, slurred speech, coordination;
- the advanced form of trypanosomiasis is characterized by convulsions of the extremities, epileptic seizures, nervous and physical exhaustion, respiratory paralysis, coma, and death.
For the diagnosis of trypanosomiasis, the Romanovsky-Giemsa test, immunofluorescence reaction, enzyme-linked immunosorbent assay (ELISA), lymph node puncture are used. Confirmation of the diagnosis is often carried out by introducing the blood of a sick person into laboratory pigs. Treatment of sleeping sickness involves taking special medications. In the absence of therapy with a high degree of probability, the patient may have a fatal outcome.
Lamblia
Microscopic protozoa (synonyms - giardia or giardia) with four pairs of flagella are full-cycle parasites in the human body. Under certain conditions, they cause the disease giardiasis. Giardia attach to the wall of the small intestine with a large sucker, often settle in the ducts of the liver, gallbladder and other internal organs.
In a note!
Infection with protozoa occurs with food, water, in unsanitary conditions. Giardia cysts with embryos remain invasive in the environment for a long time (up to 3 months in fresh water, up to 4 months in sewage). Diagnosis of protozoa is carried out by microscopy of cysts and adults in feces, blood, detection of antibodies in the ELISA study.
Leishmaniasis
These flagellated protozoa cause the disease leishmaniasis, which is common in tropical and subtropical countries. Infection occurs in a transmissible way: when biting with saliva of blood-sucking insects, animals (dogs, ground squirrels). Mosquitoes, midges, horseflies, ticks can be carriers. There are two types of leishmaniasis in humans:
- skin and mucocutaneous form (pendinskaya ulcer) - leishmania lives and multiplies on human skin, causing inflammation, swelling, ulceration, trophic ulcers, damage to the respiratory tract;
- visceral form - leishmanias settle in the internal organs (spleen, liver, lungs, heart).
A characteristic sign of cutaneous leishmaniasis is the formation of brownish nodules (leishmaniasis) at the site of insect bites. They are then replaced by round, difficult-to-heal ulcers with purulent exudate. The disease lasts for 1-2 years, leaving scars on the skin. In the visceral form, leishmaniasis causes dysfunction of the adrenal glands, kidneys, liver, and spleen. When diagnosing leishmania, they are found in the bone marrow, lymph nodes, skin scrapings, and blood.
In a note!
Treatment of leishmaniasis involves quarantine measures, patient isolation, and medication.
trichomonas
These are the simplest parasites of the human internal environment, which are transmitted sexually, through household contact or as a result of birth infection from mother to child. There are oral, intestinal, and urogenital varieties of Trichomonas. Protozoa are the causative agents of trichomoniasis/trichomoniasis. Urogenital trichomoniasis of the genitourinary system is widespread. The chronic form of the disease threatens impotence and persistent infertility. Characteristics of Trichomonas parasitism:
- body size - up to 18 microns, moves quickly due to mobile flagella;
- drug resistant, determining the chronic course of trichomoniasis;
- quickly die in the environment, in the air, under the direct rays of the sun;
- remain for a long time in damp cloths, sponges, towels, soap dishes;
- frequent infection during sexual intercourse of the vaginal, oral-vaginal type;
- Trichomonas contribute to the development of candidiasis, vulvitis, chlamydia, gonorrhea, cystitis.
Diagnosis of trichomoniasis includes detection of Trichomonas in swabs from the genitalia. Treatment involves the use of drugs, treatment with antiseptics. Therapy is carried out on both partners to prevent relapse. Prevention of urogenital trichomoniasis includes recommended measures for all sexually transmitted diseases.
dysenteric amoeba
This sarcode microorganism is a parasite that causes dangerous diseases in humans. There are two forms of dysentery amebiasis: intestinal and extraintestinal (hepatic or pulmonary). The disease begins 7-10 days after infection with symptoms: bloody diarrhea, fever, vomiting.
If left untreated, the consequences of amebiasis develop: dehydration, exhaustion, weakness, internal bleeding, liver abscess. Infection occurs most often by the fecal-oral route. Carriers of amoeba cysts can be insects: flies, horseflies. During diagnosis, tissue forms of protozoa are found in the feces. Treatment of amebiasis is stationary, with the use of antibiotics.
malarial plasmodium
Representative of the simplest sporozoa, the causative agent of a dangerous disease - malaria. The human body serves as an incubator where the life cycle of the parasite takes place. Characteristics of parasitism:
- infection with plasmodium sporozoites occurs when bitten by a malarial mosquito;
- sporozoites enter the bloodstream with the saliva of an infected insect;
- sporozoites settle in the liver, penetrate into its cells (hepatocytes);
- here the merozoites are formed by mitotic replication;
- when hepatocytes are destroyed, merozoites penetrate erythrocytes;
- from merozoites as a result of the sexual cycle gametocytes are formed;
- a mosquito becomes infected with gametocytes when bitten by an infected person;
- in the body of a mosquito, gametocytes become oocysts and then sporozoites;
- a mosquito infects a healthy person and the cycle repeats itself.
The destruction of erythrocytes and the release of gametocytes into the bloodstream is accompanied in humans by attacks of fever, vomiting, anemia, seizures, and joint pain. In severe cases, the risk of death increases. Malaria often takes on a relapsing character with phases of exacerbation and rest. Different protozoa cause tropical, three- and four-day malaria. The main therapeutic and diagnostic agent is quinine, natural from cinchona or artificially synthesized.
Infusoria balantidia coli
This agent that causes balantidia disease (or infusing dysentery) lives in the large intestine, causing bleeding ulcers on its walls. Protozoan infection occurs from domestic animals, mainly the carrier is a pig. Characteristics of anatomy and parasitism:
- the body of the balantidia is ovoid with a dense and strong shell (pellicle);
- on the surface there are many cilia that serve for movement;
- the sexual form of the parasite is necessary for reproduction by simple fission;
- the asexual form (cysts) enters the environment with feces;
- The route of human infection with cysts is fecal-oral.
The resettlement of protozoa in the intestines is accompanied in humans by headache, vomiting and dyspepsia. The acute stage of balantidiasis is manifested by a feverish state, signs of severe intoxication, loose stools with blood clots. In the absence of timely treatment, a fatal outcome is possible.
Toxoplasma gondii
Crescent-shaped microscopic spore protozoa of the order Coccidia are widely distributed in the environment. They are the causative agents of the disease - toxoplasmosis. In healthy people, ingested pests are destroyed by immune cells. Characteristics of the disease caused by protozoan parasites in humans:
- often toxoplasmosis is asymptomatic, after recovery, immunity develops;
- the parasite affects the organs of vision, the reproductive, nervous, lymphatic, liver, spleen systems;
- during pregnancy, toxoplasmosis causes serious congenital pathologies in the fetus or its death;
- the acute form causes seizures, paralysis, liver hypertrophy, heart problems;
- in a chronic course, dysfunctions of the heart, damage to the organs of vision are possible.
The main hosts of protozoa are felines. Huge colonies of Toxoplasma are formed on their body from oocysts. People are intermediate hosts, they are infected through food, domestic-contact or oro-faecal.