Protozoan parasites in humans are the causative agents of protozoal infections (or protozoosis). These diseases are contagious, threatening serious complications and consequences. Therefore, protozoosis requires timely diagnosis, accurate identification of the pathogen and proper treatment.
What are protozoan parasites
This is a group of unicellular microorganisms that are not able to independently generate nutrients. In the process of life, they use other creatures, causing them serious illnesses. The most common human protozoan parasites are listed below:
- flagella - Giardia, Leishmania, Trichomonas, Trypanosoma;
- sarcodal - dysenteric amoeba;
- ciliates - bursaria, balantidia;
- sporozoans - malarial plasmodium, coccidia, piroplasms.
Trypanosoma
The simplest parasite whose life cycle takes place in the body of ungulates (antelopes) or an infected person. Carriers are tse-tse flies, which, when bitten by a person, inject saliva with protozoa into his skin.
On a note!
For the development of the disease (African trypanosomiasis or sleeping sickness), it is necessary to introduce about 400 trypanosomes. With one bite of a tse-tse fly, up to half a million individuals of the parasite fall.
Features of parasitism and disease:
- trypanosomes initially circulate in the bloodstream of an infected person, causing trypanids on the skin (swelling of the face, eyelids), fever with a temperature of up to 40°C, swollen lymph nodes;
- then unicellular parasites migrate into the cerebrospinal fluid, causing drowsiness, iridocyclitis, chronic fatigue, lethargy, impaired speech, coordination;
- the advanced form of trypanosomiasis is marked by convulsions of the limbs, epileptic 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 the lymph nodes are used. Confirmation of the diagnosis is often carried out by introducing the blood of a sick person to laboratory pigs. Sleeping sickness treatment involves taking special medications. In the absence of therapy with a high degree of probability, a fatal outcome of the patient is possible.
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 are attached to the wall of the small intestine with a large sucker, 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 flagellar protozoa cause the disease leishmaniasis, which is common 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, gadflies, ticks can be carriers. There are two types of leishmaniasis in humans:
- skin and mucocutaneous form (pendinskaya ulcer) - leishmania live and multiply in the human skin, causing inflammation, swelling, ulceration, trophic ulcers, respiratory tract damage;
- visceral form - leishmania are settled in the internal organs (spleen, liver, lungs, heart).
A characteristic sign of cutaneous leishmaniasis is the formation of brownish nodules (leishmaniomas) 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 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.
On 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 with impotence and persistent infertility. Features of parasitism of Trichomonas:
- body size - up to 18 microns, quickly move due to mobile flagella;
- resistant to drugs, determining the chronic course of trichomoniasis;
- quickly die in the environment, in the air, under the direct rays of the sun;
- long remain 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 the detection of Trichomonas in swabs from the genitals. Treatment involves the use of drugs, treatment with antiseptics. Therapy is carried out in both partners to avoid 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 dysentery amoebiasis - intestinal and extraintestinal (hepatic or pulmonary). The disease begins 7-10 days after infection with symptoms - bloody diarrhea, fever, vomiting.
If untreated, the consequences of amoebiasis develop - dehydration, exhaustion, weakness, internal bleeding, liver abscess. Infection most often occurs by the oral-fecal route. Carriers of amoeba cysts can be insects - flies, gadflies. During the diagnosis, tissue forms of protozoa are found in the feces. Treatment of amebiasis is stationary, with the use of antibiotics.
Malarial Plasmodium
A representative of the simplest sporozoans, the causative agent of a dangerous disease - malaria. The human body serves as an incubator where the life cycle of the parasite takes place. Features of parasitism:
- infection with sporozoites of plasmodium 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 merozoites are formed by mitotic replication;
- when hepatocytes are destroyed, merozoites penetrate into 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 pass into oocysts and then into sporozoites;
- a mosquito infects a healthy person, and the cycle repeats.
The destruction of erythrocytes and the release of gametocytes into the bloodstream is 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 relapsing character with phases of exacerbation and rest. Different protozoa cause tropical malaria, three-day and four-day. The main therapeutic and diagnostic tool is quinine - natural cinchona or artificially synthesized.
Infusoria balantidia coli
This causative agent of the disease balantidia (or infusor dysentery) lives in the large intestine, causing bleeding ulcers on its walls. Infection with protozoa occurs from domestic animals, mainly the carrier is a pig. Features of anatomy and parasitism:
- the body of the balantidia is ovoid with a dense, 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;
- asexual form (cysts) enters the environment with feces;
- The route of human infection with cysts is oral-fecal.
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
Microscopic, crescent-shaped 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. Features of the disease caused by protozoan parasites in humans:
- often toxoplasmosis is asymptomatic, after recovery, immunity is developed;
- the parasite affects the organs of vision, the reproductive, nervous, lymphatic systems, liver, spleen;
- during pregnancy, toxoplasmosis causes severe congenital pathologies in the fetus or its death;
- the acute form proceeds with convulsions, 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. In their body, huge colonies of Toxoplasma are formed from oocysts. People are intermediate hosts, they become infected by alimentary, contact-household or oral-fecal way.