The simplest parasite is an organism that is adapted to invade and live in the cells and tissues of other organisms. The simplest parasites cannot live alone in an open environment like other protozoa, but must invade the body of another organism for protection and nutrition.
The simplest parasites and their varieties
The simplest organisms are eukaryotic systems that exist as structurally and functionally independent individual cells (including those species that are gregarious or that form colonies). Protozoa develop relatively complex subcellular features (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 visible to the naked eye. As single-celled eukaryotes, they move to survive, feed, and reproduce.
There are some of the simplest parasites that cause problems. They are present in our food, soil and water and can make us seriously ill if they ever 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 the central nervous system (brain, cranial nerves and spinal cord), while others live in the intestines, causing symptoms such as diarrhea, and they are not deadly.
There are four types of protozoan parasites, classified according to how they move:
- sarcodes are a group of amoebae that move through pseudopods and contractions that change the shape of their cells;
- mastigophores move with the help of flagella;
- siliophores use cilia;
- sporozoans are immobile when in their mature stage.
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 characteristics are responsible for many of the simplest infections and quickly cause acute symptoms of the disease.
The developmental stages of protozoan parasites that occur within the host generally consist of feeding on trophozoites and can be found intracellularly (within the host's cells) or extracellularly (in hollow organs, body fluids, or inter-cells between cells). Although trophozoites are ideal for their parasitic mode of existence, they are not very 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.
Ways 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).
- Fecal-oral transmission of ecologically stable stages of cysts: parasites pass in the feces of one host and are transmitted with food or water to another (for example, Entamoeba histolytica, Giardia duodenalis, and Balantidium coli are all forms of cysts fecal disease leading to dysentery, giardiasis, and balantidiosis).
- Transmission occurs when parasites are ingested by blood-sucking arthropods (insects or arachnids) and transmitted to new hosts through a bite (for example, Trypanosoma brucei, which is transmitted by tsetse flies and causes sleeping sickness, and Plasmodium spp. , Hemosporidia, transmitted by mosquitoes). and causing malaria).
- Predator-to-prey transmission occurs when the simplest parasite gets stuck in the victim's tissues (for example, a cow, a goat, a pig) and is eaten by a predator (in our case, a person).
The simplest human parasites and the diseases they cause.
Acanthamoeba. This parasite infects a person's eyes or brain and causes exogenous amebiasis. You 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). It lives in the intestinal mucosa, it causes ciliated dysentery, also called balantidiosis.
Blastocystis (Blastocystis). This parasite infects the intestines of the host. It enters humans through ingested food contaminated with human or animal feces. The disease caused by this parasite is called blastocytosis.
Cryptosporidium (Cryptosporidium). It lives in the human intestine. Distributed all over the world. It enters the human body through ingested food contaminated with human or animal feces.
Dysentery amoeba (Entamoeba histolytica). This simpler parasite causes intestinal amebiasis. It is most often found in areas with high population density, poor sanitation, and tropical regions. It is transmitted by the fecal-oral route.
Giardia lamblia. It lives in the lumen of the small intestine. If people consume food or water contaminated with feces, latent Giardia cysts can infect the body and cause intestinal giardiasis. It is especially dangerous for children and requires mandatory compliance with the treatment regimen.
Isospora (Isospora belli). It affects the epithelial cells of the small intestine. Distributed all over the world. It is transmitted by the fecal-oral route and is the causative agent of isosporia.
Leishmania. It parasitizes the skin and internal organs of a person. It exists around the world in various forms. Transmitted by some types of mosquitoes when bitten.
Negleria (Naegleria fowleri). It causes primary amoebic meningoencephalitis as it lives in the human brain. Infection occurs through contaminated soils, 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 tropical regions where Anopheles, also known as the anopheles mosquito, is 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 is in contact with contaminated material.
Toxoplasma (Toxoplasma gondii). It affects the liver, heart, eyes and brain. A parasite spread throughout the world. People can become infected after eating raw or undercooked pork, lamb, goat, or milk. It can also exist in contaminated food or soil due to cat feces. 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 the so-called sleeping sickness. The second parasite causes Chagas disease by affecting the blood, muscles, nerves, heart, esophagus, and intestines. It is also transmitted by insect bites.
How to treat infections caused by protozoan parasites in humans?
The treatment plan for a protozoan parasite infection will depend on the specific diagnosis. Usually your doctor will prescribe medicine, for example to treat trichomoniasis, giardiasis or cryptosporidiosis. Medication for toxoplasmosis is generally not prescribed unless there are conditions for this in the form of pregnancy, some other illness, or a serious and long-term infection.
Your doctor may also recommend other treatments to help relieve 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 generally recommended to drink plenty of fluids to replenish the loss in the body.
How can protozoan parasites be prevented?
There are several steps you can take 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 food to the recommended core temperature.
- drink clean water, including bottled water, when you travel;
- avoid swallowing water from lakes, streams, or ponds;
- Avoid cat litter and feces during pregnancy.
If you suspect 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 other people.