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]
For more information about Parasitism, read the full article at
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News tagged with parasites
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 ...
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 ...
Tiny UK parasitoid wasp discovered
Oct 20, 2009 |
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(PhysOrg.com) -- A new species of parasitoid wasp that feeds on a common whitefly pest has been discovered in the UK by a Natural History Museum scientist.
Parasite growth hormone pushes human cells to liver cancer
Oct 09, 2009 |
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Scientists have found that the human liver fluke (Opisthorchis viverrini) contributes to the development of bile duct (liver) cancer by secreting granulin, a growth hormone that is known to cause uncontrolled growth of cel ...
Gut worms may protect against house-dust mite allergy
Sep 28, 2009 |
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(PhysOrg.com) -- A study conducted in Vietnam has added further weight to the view that parasitic gut worms, such as hookworm, could help in the prevention and treatment of asthma and other allergies.
Sex life may hold key to honeybee survival
Sep 14, 2009 |
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The number and diversity of male partners a queen honeybee has could help to protect her children from disease, say University of Leeds scientists, who are investigating possible causes of the widespread increase ...
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 ...
Diarrhea disorder Giardiasis caused by two different parasite species
Aug 21, 2009 |
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(PhysOrg.com) -- Researchers from Uppsala University and the Karolinska Institute have found major genetic differences between the human variants of the intestinal parasite Giardia intestinalis. Sequencing of the genomes ...
New discovery points the way towards malaria 'vaccine'
Aug 21, 2009 |
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Malaria kills anywhere from one to three million people around the world annually and affects the lives of up to 500 million more. Yet until now, scientists did not fully understand exactly how the process that caused the ...
Parasites persuade immune cells to invite them in for dinner, says new research
Aug 21, 2009 |
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The parasites that cause leishmaniasis use a quirky trick to convince the immune system to effectively invite them into cells for dinner, according to a new study published today in PLoS Pathogens. The re ...
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 ...
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.
Portuguese scientists show Schistosoma haematobium direct link to tumours
Jul 30, 2009 |
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Schistosoma haematobium (S. haematobium) is a parasitic flatworm that infects millions of people, mostly in the developing world, and is associated with high incidence of bladder cancer although why is not clear. Now, however, ...
Discovery to aid in future treatments of third-world parasites
Jul 27, 2009 |
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Schistosomiasis, one of the most important of the neglected tropical diseases, is caused by infection with parasitic helminths of the genus Schistosoma. These parasites are long lived (>10 years) and dwell ...
