Protozoan parasites in humans are the causative agents of protozoan infections (or protozoosis). These diseases are contagious and threaten serious complications and consequences. Therefore, protozoan disease requires timely diagnosis, accurate identification of the pathogen and appropriate treatment.
What are protozoan parasites
This is a group of single-celled microorganisms that are not able to independently generate nutrients. During life, they use other creatures, causing them serious illnesses. The most common human protozoan parasites are listed below:
- flagella - giardia, leishmania, trichomonas, trypanosoma;
- sarcodal amoeba - dysenteric;
- ciliates - bursaria, balantidia;
- sporozoa - malarial plasmodium, coccidia, piroplasma.
Trypanosome
The simplest parasite, the life cycle of which takes place in the body of ungulates (antelopes) or an infected person. Carriers are tsetse flies which, when bitten by a person, inject saliva containing protozoa into their skin.
On a note!
For the development of the disease (African trypanosomiasis or sleeping sickness), the introduction of about 400 trypanosomes is necessary. With one bite of a tsetse fly, up to half a million individuals of the parasite fall out.
Characteristics of Parasitism and Disease:
- trypanosomes initially circulate in the blood of an infected person, causing trypanids on the skin (swollen face, eyelids), fever with temperature up to 40°C, swollen lymph nodes;
- then the unicellular parasites migrate into the cerebrospinal fluid, causing drowsiness, iridocyclitis, chronic fatigue, lethargy, speech and coordination disorders;
- the advanced form of trypanosomiasis is characterized by convulsions of the limbs, seizures, nervous and physical exhaustion, respiratory paralysis, coma and death.
For the diagnosis of trypanosomiasis, the Romanovsky-Giemsa test, immunofluorescence reaction, enzyme immunoassay (ELISA), puncture of lymph nodes are used. Diagnosis confirmation is often done by introducing the blood of a sick person into laboratory pigs. The treatment of sleeping sickness consists of taking special medications. In the absence of treatment with a high degree of probability, a fatal outcome of the patient is possible.
lambia
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 are attached to the wall of the small intestine with a large suction cup, often settle in the ducts of the liver, gallbladder and other internal organs.
On 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.
Leishmania
These flagellated protozoa cause leishmaniasis, a common disease in tropical and subtropical countries. Infection occurs in a transmissible way - when bitten with saliva of blood-sucking insects, animals (dogs, ground squirrels). Mosquitoes, mosquitoes, horseflies, ticks can be carriers. There are two types of leishmaniasis in humans:
- cutaneous and mucocutaneous form (pendinskaya ulcer) - leishmania live and multiply in human skin, causing inflammation, swelling, ulceration, trophic ulcers, damage to the respiratory tract;
- visceral form - leishmanias are installed in the internal organs (spleen, liver, lungs, heart).
A characteristic sign of cutaneous leishmaniasis is the formation of brownish nodules (leishmaniamas) at the site of insect bites. Then they are replaced by round, difficult to heal ulcers with purulent exudate. The disease drags on for 1-2 years, leaving scars on the skin. In its visceral form, leishmaniasis causes dysfunction of the adrenal glands, kidneys, liver and spleen. When diagnosed with leishmania, they are found in bone marrow, lymph nodes, skin scrapings, and blood.
On a note!
The treatment of leishmaniasis involves quarantine measures, isolation of the patient and medication.
Trichomonads
These are the simplest parasites of the human internal environment, which are transmitted sexually, through family contact or as a result of infection at birth 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 with impotence and persistent infertility. Characteristics of Trichomonas parasitism:
- body size - up to 18 microns, rapidly moving due to mobile flagella;
- drug resistant, determining the chronic course of trichomoniasis;
- quickly die in the environment, in the air, under direct sunlight;
- long stay on wet washcloths, 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 genitals. Treatment involves the use of drugs, treatment with antiseptics. Therapy is performed in both partners to prevent relapses. Prevention of urogenital trichomoniasis includes measures recommended for all sexually transmitted diseases.
dysenteric amoeba
This sarcode microorganism is a parasite that causes dangerous diseases in humans. There are two forms of dysenteric amebiasis - intestinal and extra-intestinal (hepatic or pulmonary). The disease begins 7-10 days after infection with symptoms - bloody diarrhea, fever, vomiting.
If left untreated, the consequences of amoebiasis develop - dehydration, exhaustion, weakness, internal bleeding, liver abscess. Infection most often occurs via the fecal-oral route. Carriers of amoeba cysts can be insects - flies, horseflies. During diagnosis, tissue forms of protozoa are found in the stool. Treatment of amoebiasis is stationary, with the use of antibiotics.
Malaric 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 mosquito carrying malaria;
- sporozoites enter the bloodstream with the saliva of an infected insect;
- sporozoites settle in the liver, enter its cells (hepatocytes);
- here, merozoites are formed by mitotic replication;
- when the hepatocytes are destroyed, the merozoites enter the erythrocytes;
- from merozoites as a result of the sexual cycle, gametocytes are formed;
- a mosquito is infected with gametocytes when bitten by an infected person;
- in the body of a mosquito, the gametocytes pass into the oocysts and then into the sporozoites;
- a mosquito infects a healthy person and the cycle repeats itself.
The destruction of erythrocytes and the release of gametocytes into the bloodstream are accompanied in humans by bouts of fever, vomiting, anemia, convulsions and joint pain. In severe cases, the risk of death increases. Malaria often takes on a recurrent character with phases of exacerbation and rest. Different protozoa cause tropical, three-day and four-day malaria. The main therapeutic and diagnostic agent is quinine - natural from cinchona or artificially synthesized.
Infusoria balantidia coli
This causative agent of the disease balantidia (or dysentery infusor) lives in the large intestine, causing bleeding ulcers on its walls. Protozoan infection occurs in domestic animals, mainly the carrier is a pig. Features of Anatomy and Parasitism:
- the body of balantidia is ovoid with a dense, solid shell (pellicle);
- on the surface, many cilia are used 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 oral-fecal.
The reinstallation of protozoa in the intestines is accompanied in humans by headaches, 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
The microscopic, crescent-shaped spore protozoa of the order Coccidia are widely distributed in the environment. These are the causative agents of the disease - toxoplasmosis. In healthy people, ingested parasites are destroyed by immune cells. Features of the disease caused by protozoan parasites in humans:
- often toxoplasmosis is asymptomatic, after recovery immunity develops;
- the parasite affects the organs of vision, reproductive, nervous, lymphatic systems, liver, spleen;
- during pregnancy, toxoplasmosis causes severe congenital pathologies in the fetus or its death;
- the acute form results in convulsions, paralysis, enlarged liver, heart problems;
- in a chronic course, malfunctions of the heart, damage to the organs of vision are possible.
The main hosts of protozoa are felines. In their body, huge colonies of Toxoplasma are formed from oocysts. Humans are intermediate hosts, they become infected through food, contact-household or oral-faecal routes.