From Latin parasitus (although with more remote origin in a Greek word that means "diner" ), a parasite It is an organism that lives at the expense of another species . The parasite, which can be animal or plant, feeds on the other organism, weakening it although, usually, without killing it.
The biological interaction that involves parasites is known as parasitism . The species that hosts the parasite is known as Guest or host and it undergoes a depauperation of its reproductive capacity before the action of the other organism that, in turn, manages to improve its own conditions and its ability to survive.
It can be said, therefore, that the parasites benefit from the association they establish with the other body, while the latter is harmed by the type of interaction .
In some cases, the parasites themselves can become hosts of a third species, which is known as hyperparasite . In this way a chain is produced where the hyperparasite lives at the expense of the parasite, and the parasite does the same with its Guest .
With the running of weather and the successive generations, the host organisms manage to develop certain defense mechanisms that move the parasites away or minimize their field of action. Parasites, however, can achieve physiological and morphological transformations through the natural selection .
It should be mentioned that symbiotic relationships between a parasite and its host can be beneficial for the lifetime and the evolution of the latter, although it concerns the minority of cases. The action of some of the parasites that most commonly attack our species is detailed below:
* hookworms: are worms that begin their life cycle outside our body and reach it through fruit, vegetables or Water contaminated Once in the intestine, they stick to your wall and feed on the blood to grow, which can cause a kind of anemia known as ankylostomiasis. Among the symptoms caused by the presence of these parasites are diarrhea, nausea, loss of strength and pain in the abdomen;
* platelmintos trematodes: find their habitat in the bloodstream of their hosts and are the cause of the schistosomiasis (a disease that causes strong fevers and hives, among other symptoms, and can cause death). Before entering another organism, they live in the water. Their presence is manifested through damage and inflammation in some organs, mainly in the liver, and they can stay in the same body for several decades, sometimes without showing symptom for a long time. When they do, these are usually coughs, various pains, lethargy and fever;
* wuchereria bancrofti: they are moved by mosquitoes and released in the blood from the host. Their larvae target lymph nodes, especially in the genitals and lower extremities, and reach adulthood within twelve months. They usually cause a disease of the group known as filariasisespecially the elephantiasis (causes excessive growth of certain parts of the body). Among the symptoms that are noticed in its presence are chills, pain in the lymph nodes, fever and skin infections;
* entamoeba histolytica: It is a single-cell organism that attacks people and other primates. It is found in fruits, wet soils and in water. The contamination Fecal collaborates with its spread. It is worth mentioning that the death rate attributed to it exceeds that of the rest of the protozoa. Diarrhea, weakness, weight loss and liver abscess are some of the symptoms of its passage through our body.
In the colloquial language
Finally, the parasite is classified as person who lives, or tries to live, at the expense of another subject, taking advantage of his material resources. For example: “Maximilian is a parasite; since he has never earned his own money, he would be sleeping on the street if it were not for his parents ”.