Diseases, Conditions, Syndromes

New insights into immune responses to malaria

Advanced technologies have been used to solve a long-standing mystery about why some people develop serious illness when they are infected with the malaria parasite, while others carry the infection asymptomatically.

Diseases, Conditions, Syndromes

Blocking how the malaria parasite suppresses the immune response

The parasites that cause severe malaria are well-known for the sinister ways they infect humans, but new research may lead to drugs that could block one of their most reliable weapons: interference with the immune response.

Diseases, Conditions, Syndromes

Investigational malaria vaccine gives strong, lasting protection

Two U.S. Phase 1 clinical trials of a novel candidate malaria vaccine have found that the regimen conferred unprecedentedly high levels of durable protection when volunteers were later exposed to disease-causing malaria parasites. ...

Diseases, Conditions, Syndromes

Incidents of serious parasitic disease on the rise in Alberta, Canada

A rare parasitic infection imported from Europe continues to take root in Alberta, Canada. The province is now the North American hotspot for human alveolar echinococcosis (AE), which takes the form of a growth in the liver, ...

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Parasitism

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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