The simplest parasite is an organism that is adapted to invade and live in cells and tissues of other organisms. Even the simplest parasites cannot live on their own in an open environment like other protozoa, but must invade the body of another organism to receive protection and nourishment.
The simplest pests and their varieties
The simplest organisms are eukaryotic systems that exist as structurally and functionally independent single cells (including gregarious or colony-forming species). Protozoa develop relatively complex subcellular traits (membranes and organelles) that allow them to survive in harsh environmental conditions. Most protozoa are microscopic organisms, and only a few of them grow large enough to be seen with the naked eye. As single-celled eukaryotes, they move around to survive, feed, and reproduce.
There are some of the simpler parasites that cause problems. They are present in our food, our soil and our water and can make us very sick if they get inside us.
Each different protozoan parasite can cause different diseases in our body. Some of them can cause serious diseases of the respiratory tract (passage of air from the nose to the lungs) and central nervous system (brain, cranial nerves and spinal cord), while others live in the intestines, causingsymptoms such as diarrhea, and are not fatal.
There are four types of protozoan parasites, which are classified according to how they travel:
- Sarcodia are a group of amoeba that move with the help of pseudopodia and contractions that change the shape of their cells;
- mastigophores move with the help of flagella;
- siliophores use eyelashes;
- sporozoa are immobile when mature.
Life cycles of protozoan parasites
Most protozoa have enormous reproductive potential because they have a short generation time, undergo rapid sequential development, and produce large numbers of offspring asexually or sexually. These features are responsible for many of the simpler infections, quickly causing acute symptoms of the disease.
The developmental stages of protozoan parasites that occur in the host usually consist of feeding on trophozoites and can be found intracellularly (in host cells) or extracellularly (in hollow organs, bodily fluids orinternodes between cells). Although trophozoites are ideal for their parasitic mode of existence, they are poorly resistant to external environmental conditions and do not survive long outside their hosts. To move from host to host, protozoan parasites use one of four main modes of transmission: direct, fecal-oral, transmissible, and predator-to-prey.
Modes of transmission of protozoan parasites to humans
- Direct transmission of parasites through intimate contact with the body - sexually (for example, Trichomonas spoke of fungi, which cause trichomoniasis in humans).
- Faecal-oral transmission of ecologically stable stages of cysts - parasites pass in the stool from one host and are transmitted with food or water to another (eg, Entamoeba histolytica, Giardia duodenalis, and Balantidium coli are allforms of fecal cysts that lead to dysentery, giardiasis and balantidiosis).
- Transmission occurs when parasites are ingested by blood-sucking arthropods (insects or arachnids) and transmitted to new hosts by bite (for example, Trypanosoma brucei, transmitted by tsetse flies and causing sleeping sickness, and Plasmodium spp. Haemosporidia, transmitted by mosquitoes and causing malaria).
- Transmission from predator to prey occurs when the simplest parasite gets stuck in the tissues of the victim (for example, a cow, a goat, a pig) and is eaten by a predator (in our case, one person).
The simplest human parasites and the diseases they cause
Acanthamoeba. This parasite infects a person's eyes or brain and causes exogenous amebiasis. He can live in any region of the world. People can get it by cleaning contact lenses with tap water.
Babesia. It infects red blood cells and causes a disease called babesiosis. Different types of parasites live in different parts of the world. It is transmitted by ticks when bitten.
Balantidium (Balantidium coli). Lives in the intestinal lining, causes ciliated dysentery, also called balantidiosis.
Blastocystis (Blastocystis). This parasite infects the intestines of the host. It enters humans through the ingestion of food contaminated with human or animal excreta. The disease caused by this parasite is called blastocytosis.
Cryptosporidium (Cryptosporidium). Lives in the human intestine. Distributed worldwide. It enters the human body through the ingestion of food contaminated with human or animal feces.
Amoeba dysentery (Entamoeba histolytica). This simplest parasite causes intestinal amebiasis. Most often found in areas with high population density, poor sanitation and tropical regions. It is transmitted by the fecal-oral route.
Giardia lamblia. Lives in the lumen of the small intestine. If people consume food or water contaminated with feces, dormant Giardia cysts can infect the body, causing intestinal giardiasis. It is especially dangerous for children and requires compulsory adherence to the treatment regimen.
Isospore (Isospora belli). Affects epithelial cells in the small intestine. Distributed all over the world. It is transmitted by the fecal-oral route and is the causative agent of isosporia.
Leishmania. Parasitizes a person's skin and internal organs. It exists all over the world in various forms. Transmitted by certain types of mosquitoes when bitten.
Negleria (Naegleria fowleri). Causes primary amoebic meningoencephalitis because it lives in the human brain. Infection occurs through contaminated soil, swimming pools and contaminated water.
Plasmodium (Plasmodium falciparum, P. vivax, P. ovale, P. malariae). The parasites enter the red blood cells and cause malaria. They exist in the tropics where Anopheles, also called Anopheles mosquitoes, are transported.
Rhinosporidium seeberi. It multiplies in the nose and nasopharynx, growing there as spores. It exists in India and Sri Lanka. People who swim in public waters can become infected with the parasite when the nasal mucosa comes in contact with contaminated material.
Toxoplasm (Toxoplasma gondii). Affects the liver, heart, eyes and brain. A parasite widespread all over the world. People can get infected after eating raw or undercooked pork, lamb, goat, or milk. May also exist in food or soil contaminated with cat droppings. The disease caused by this parasite is called toxoplasmosis or parasitic pneumonia.
Trichomonas (Trichomonas vaginalis). It infects the female urogenital tract. Symptoms differ in men and women. It is the causative agent of trichomoniasis, a sexually transmitted infection.
Trypanosomes (Trypanosoma brucei, Trypanosoma cruzi). The first type of parasite affects the central nervous system, blood, and lymph. It is transmitted by the tsetse fly and causes what is called sleeping sickness. The second parasite causes Chagas disease by affecting the blood, muscles, nerves, heart, esophagus and intestines. Also transmitted by insect bites.
How to treat infections caused by protozoan parasites in humans?
The treatment plan for a protozoan parasitic infection will depend on the specific diagnosis. Usually your doctor will prescribe medicines, for example, to treat trichomoniasis, giardiasis or cryptosporidiosis. Usually, drugs are not prescribed for toxoplasmosis unless there are conditions for it in the form of pregnancy, other illness or severe and prolonged infection.
The doctor may also recommend other treatments to help relieve the symptoms. For example, many parasitic infections can cause diarrhea, which often leads to dehydration. Therefore, when treating an infection caused by protozoan parasites, it is usually recommended to drink plenty of fluids to replenish the loss in the body.
How to prevent protozoan parasites?
There are several things you can do to reduce your risk of getting a parasitic infection:
- practice safe sex using a condom;
- wash your hands regularly, especially after handling raw food or feces;
- Cook the food to the recommended core temperature.
- drink clean water, including bottled water, when traveling;
- avoid swallowing water from lakes, streams or ponds;
- avoid litter and cat feces during pregnancy.
If you think you have a parasitic infection, make an appointment with your doctor. They can help diagnose the cause of your symptoms and recommend a treatment plan. The sooner you start treatment, the sooner you can help stop the infection from spreading to others.