Parasitism
hideParasitism is a type of symbiotic relationship between two different organisms where one organism, the parasite, takes favor from the host, sometimes for a prolonged time. In general, parasites are much smaller than their hosts, show a high degree of specialization for their mode of life, and reproduce more quickly and in greater numbers than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and diverse animals such as tapeworms, flukes, the Plasmodium species, and scabs. Parasitism is differentiated from parasitoidism, a relationship in which the host is always killed by the parasite such as moths, butterflies, ants, flies and others.
The harm and benefit in parasitic interactions concern the biological fitness of the organisms involved. Parasites reduce host fitness in many ways, ranging from general or specialized pathology (such as castration), impairment of secondary sex characteristics, to the modification of host behaviour. Parasites increase their fitness by exploiting hosts for food, habitat and dispersal.
Although the concept of parasitism applies unambiguously to many cases in nature, it is best considered part of a continuum of types of interactions between species, rather than an exclusive category. Particular interactions between species may satisfy some but not all parts of the definition. In many cases, it is difficult to demonstrate that the host is harmed. In others, there may be no apparent specialization on the part of the parasite, or the interaction between the organisms may be short-lived. In medicine, only eukaryotic organisms are considered parasites, with the exclusion of bacteria and viruses. Some branches of biology, however, regard members of these groups as parasitic.[citation needed]
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News tagged with parasites
Measuring and modeling blood flow in malaria
Nov 23, 2009 |
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When people have malaria, they are infected with Plasmodium parasites, which enter the body from the saliva of a mosquito, infect cells in the liver, and then spread to red blood cells. Inside the blood cells, the parasites ...
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Scientists reveal malaria parasites' tactics for outwitting our immune systems
Nov 30, 2009 |
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Malaria parasites are able to disguise themselves to avoid the host's immune system, according to research funded by the Wellcome Trust and published today in the journal Proceedings of the National Academy of ...
Nuclear science to fight sleeping sickness
Nov 27, 2009 |
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The International Atomic Energy Agency on Friday announced an agreement to help African nations battle the tsetse fly, the main carrier of parasites that causes sleeping sickness with its bites.
Discovery opens new avenues for treating devastating freshwater fish parasite, 'Ich'
Dec 02, 2009 |
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Researchers from the University of Georgia College of Veterinary Medicine have made an "unexpected" dual discovery that could open new avenues for treating Ichthyophthirius multifiliis, or "Ich", a devastating ...
Why we outlive our ape ancestors
Dec 02, 2009 |
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In spite of their genetic similarity to humans, chimpanzees and great apes have maximum lifespans that rarely exceed 50 years. The difference, explains USC Davis School of Gerontology Professor Caleb Finch, is that as humans ...
Ants are friendly to some trees, but not others
Nov 06, 2009 |
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Tree-dwelling ants generally live in harmony with their arboreal hosts. But new research suggests that when they run out of space in their trees of choice, the ants can get destructive to neighboring trees.
Study shows link between influenza virus and fever
Nov 16, 2009 |
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One feature of the "new influenza" is a sudden rise in temperature. Up to now it was not exactly understood how this reaction occurs. Scientists at the University of Bonn and the Technical University of Munich, Germany, have ...
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