Related topics: malaria
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
Scientists report original source of malaria
Aug 03, 2009 |
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Researchers have identified what they believe is the original source of malignant malaria: a parasite found in chimpanzees in equatorial Africa.
Parasite breaks its own DNA to avoid detection
Apr 15, 2009 |
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The parasite Trypanosoma brucei, which causes African sleeping sickness, is like a thief donning a disguise. Every time the host's immune cells get close to destroying the parasite, it escapes detection by rearranging its DN ...
Deadly parasite's rare sexual dalliances may help scientists neutralize it
Apr 09, 2009 |
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For years, microbiologist Stephen Beverley, Ph.D., has tried to get the disease-causing parasite Leishmania in the mood for love. In this week's Science, he and colleagues at the National Institutes of Health report that t ...
Research supports toxoplasmosis link to schizophrenia
Mar 11, 2009 |
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Scientists have discovered how the toxoplasmosis parasite may trigger the development of schizophrenia and other bipolar disorders.
How mosquitoes could teach us a trick in the fight against malaria
Mar 05, 2009 |
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(PhysOrg.com) -- The means by which most deadly malaria parasites are detected and killed by the mosquitoes that carry them is revealed for the first time in research published today in Science Express. The di ...
Parasite evades death by promoting host cell survival
Dec 08, 2009 |
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Researchers have discovered how the parasite Trypanosoma cruzi, which causes Chagas' disease, prolongs its survival in infected cells. A protein on the parasite activates the enzyme Akt, which blocks cell ...
A boy for every girl? Not even close
Sep 10, 2009 |
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In a perfect world, for every boy there would of course be a girl, but a new study shows that actual sex ratios can sometimes sway very far from that ideal. In fact, the male-to-female ratio of one tropical butterfly has ...
Friendly gut bacteria lend a hand to fight infection, study suggests
Aug 19, 2009 |
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Immunology researchers at UT Southwestern Medical Center have found that bacteria present in the human gut help initiate the body's defense mechanisms against Toxoplasma gondii, the parasite responsible for to ...
Daily temperature shifts may alter malaria patterns
Aug 03, 2009 |
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Daytime temperature fluctuations greatly alter the incubation period of malaria parasites in mosquitoes and alter transmission rates of the disease. Consideration of these fluctuations reveals a more accurate picture of climate ...
Parasites keep things sexy in 'hotspots'
Jul 23, 2009 |
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The coevolutionary struggle between a New Zealand snail and its worm parasite makes sex advantageous for the snail, whose females favor asexual reproduction in the absence of parasites, say Indiana University ...
Study finds role for parasites in evolution of sex
Jul 06, 2009 |
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What's so great about sex? From an evolutionary perspective, the answer is not as obvious as one might think. An article published in the July issue of the American Naturalist suggests that sex may have evolved in part a ...
Baboons, Humans Adapted Similarly to Malaria (w/ Video)
Jun 24, 2009 |
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(PhysOrg.com) -- Evolutionarily speaking, baboons may be our more distant cousins among primates. But when it comes to our experiences with malaria over the course of time, it seems the stories of our two ...
Birds use social learning to enhance nest defense
Jun 04, 2009 |
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Reed warblers live with the threat that a cuckoo bird will infiltrate their nest, remove one of their eggs, and replace it with the cuckoo's own. This 'parasitism' enables the cuckoo to have its young raised by unsuspecting ...
When hosts go extinct, what happens to their parasites?
Jun 01, 2009 |
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(PhysOrg.com) -- Hands wring and teeth gnash over the loss of endangered species like the panda or the polar bear. But what happens to the parasites hosted by endangered species? And although most people would ...
A connected world gives viruses the edge
May 27, 2009 |
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That's one conclusion from a new study that looked at how virulence evolves in parasites. The research examined whether parasites evolve to be more or less aggressive depending on whether they are closely ...
