Sweet success of parasite survival could also be its downfall

University of York scientists from the Department of Chemistry are part of an international team which has discovered how a parasite responsible for spreading a serious tropical disease protects itself from starvation once ...

Mother cells as organelle donors

Microbiologists at LMU and UoG have discovered a recycling process in the eukaryotic parasite Toxoplasma gondii that plays a vital role in the organism's unusual mode of reproduction.

Malaria could be felled by an Antarctic sea sponge

The frigid waters of the Antarctic may yield a treatment for a deadly disease that affects populations in some of the hottest places on earth. Current medications for that scourge—malaria—are becoming less effective as ...

A new generation of anti-malarial drugs

Malaria is endemic to large areas of Africa, Asia and South America and annually kills more than 400,000 people, a majority of whom are children under age 5, with hundreds of millions of new infections every year.

Lessons on parasitism from the curious Dicyemida

The incredible diversity of life forms on the planet led Charles Darwin to note, "From so simple a beginning, endless forms most beautiful and most wonderful have been, and are being, evolved." In order to gain a true understanding ...

How worms snare their hosts

Acanthocephala are parasitic worms that reproduce in the intestines of various animals, including fish. However, only certain species of fish are suitable as hosts. A study by the University of Bonn now shows how the parasites ...

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Parasitism 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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