Protozoa are unicellular eukaryotic organisms and there are many different kinds of these micorscopic creatures. Some dwell in the sea and provide an important part of the ecosystem as food and a system of creating detritus for sea life. They are consumed by a variety of oceanic creatures. On land, these prevalent, creatures can live in the soil and all over nature. Some protozoa move, while some do not and do not move or rely on other ways of transportation. These beings serve as food to larger creatures which in turn support large ecosystems. They even live inside other beings. You will find them residing in creatures and providing services, such as decomposing or breaking down food such as in cattle or termite digestive systems. They sometimes have a cyst stage which is dormant in their lives. They can spend this time exposed to extreme conditions and still survive. This allows parasitic protozoa to become cysts and live outside of hosts and even be passed. This is something to consider when examining how someone can get infected.
Bacteria are prokaryotic microorganisms that have a variety of types, shapes and more. They are one of the world’s first life forms. They outnumber all other life and exceed the biomass of all other life, simply because despite their microscopic size they are prevalent and may be found in almost, if not all environments and exposures. They live in and on other animals as well. Sometimes they live symbiotically, sometimes they release harmful chemical wastes, sometimes they are parasitic and sometimes they do not affect their host. Bacteria cells have no nucleus and do not usually have membrane-bound organelles. Since the 1990s they have been distinguished from their distant but similar relatives, the Archaea.
Now rickettsia are bacteria. They are pleomorphic and they are nonmotile and gram negative. They do not form spores. They can appear as cocci, rods, or thread like. They are intracellular parasites, which means they restricted to reproducing and growing in a host’s cells. They are distinguished from true bacteria by having cell walls which make it more like the gram-negative bacteria than the chlamidia (pathogenic bacteria), mycoplasma (whose lack of a cell wall gives it a resistance to antibiotics) and ureaplasma (a urease positive bacteria). They are usually carried by arthropods. Interestingly, they may be the closest living relative to the bacteria that would later evolve into the mitochondria organelles of eukaryotic cells.
A parasite is a creature which survives by feeding off of a host creature. It may do this in a variety of ways. When one creature gets benefit and the other that does not, the benefitting creature is considered a parasite if the creature not benefitting is being negatively affected. Fungi are a kingdom of eukaryotic organisms and can be one-celled or multi-celled. They are distinguished from bacteria, protists, animals and plants as a unique kingdom and include molds, yeasts and mushrooms. Genetically, they are closer to animals than plants. They are prevalent, varied and most have not even been determined. They attack crops, causes damage and breaks things down, causes illness in animals and humans and more. Many of them release dangerous chemicals that may remain in food or feed even after cold or heat processing.
Viruses are distinct from many other organisms in that they need to reside inside of the living cell of another creature. They can infect bacteria,, archaea, animals, plants and more. They help provide important qualities to the ecosystem, for instance, viruses in the ocean destroy microscopic bacteria and archae as well as other organisms. This helps initially in microscopic material, by creating detritus, the food for much of the microscopic oceanic life. On land, they are prevalent and survive in soil, organisms and are throughout the environment. Viruses spread in a variety of was on land and sea. They can transmit through insects, even on plants. They can transmit through the soil, through microscopic and not so microscopic vectors. Animals can carry them, and be bitten by insects or be eaten by a predator, further propagating the spread of the virus. Viruses are dangerous in that they prove resistant or immune to drugs, immunizations or treatments. They adapt quickly.
Arbovirus is an acronym for ARthropod-BOme virus and specifically refers to viruses that utilize arthropods as the vector. This means they go through a cycle of living in a host which carries the virus, a vector which is an organism which carries it and moves the virus, giving it to other beings. There are a variety of arboviruses, such as the yellow fever, tick-borne encephalitis virus, dengue virus, west nile virus, African swine fever, Rift Valley fever virus and more.
Transmission is the way in which the infection is spread and involves a few stages. The parasite exits the host or reservoir where it usually lives and procreates. The movement to the new host then takes place. The organism then enters the new host. It then leaves the new host, creating the cycle over again. It can be transmitted in many ways but some of the most common forms of transmission are Organism to Organism (touch, contaminated body fluids or blood, saliva or aerosol/air), Food, Water, Insects and Fomites.
Infection is when an organism infects the host organism’s body tissue. In many organisms, such as mammals, the host body reacts in ways such as inflammation and adaptive response in order to help rid the body of infection. What kind of vector carries the pathogen. The lack or presence of a cell wall or membrane lined organelles may indicate what it may resist or be able to withstand from an antibiotic.
Infestation is when the host is being invaded or overrun by parasites of pests. Normally this reference is used to specifically refer to parasitic diseases which are caused by arthropods such as lice, mites, ticks and other arthropods as well as worms. It is not always used to refer to bacteria, protozoa and fungi. They can be external or internal depending on the parasite’s location, lifestyle and age. It may also be used to refer to a location.
The disease causing organism is the organism that is causing the illness. The vehicle or vector is the organism the disease is transmitted on, and they are separate beings. It is important to note that the vector could be a variety and it is not normally intentionally trying to actively spread the disease (this is not always the case, one exception for example is cordycepts a fungus which does have some control over its host to help spread the disease for instance, another would be the protozoan Toxoplasmosis gondii). Fomites can be cleaned, animals can be treated, as can people. The parasite may not always be shedding and therefore may not always be transmittable. It depends on what it is, its lifestyle, how it is transmitted, if it can survive and for how long outside of a host body and a variety of other factors.
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