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An obligate parasite depends completely on the host to complete its life cycle, while a facultative parasite does not. Parasite life cycles involving only one host are called "direct"; those with a definitive host (where the parasite reproduces sexually) and at least one intermediate host are called "indirect".
A perspective on the evolutionary options can be gained by considering four questions: the effect on the reproductive fitness of a parasite's hosts; the number of hosts they have per life stage; whether the host is prevented from reproducing; and whether the effect depends on intensity (number of parasites per host). From this analysis ...
When an intracellular parasite goes to enter a host cell, it is particular about the type of host cell. This is because most intracellular parasites are able to infect only a few different cell types. [21] Viruses use a number of host receptors to gain entry to the cell, usually by causing endocytosis. [7]
Inside the cells they undergo spontaneous transformation into oval-shaped amastigotes. [22] [23] Granulocytes selectively kill the promastigotes by oxidative mechanism, while amastigotes are resistant. [24] Then the surviving amastigotes undergo cell division using simple binary fission. Multiplication continues until the host cell can no ...
Parasites need a host body and the haematophagous insect triatomine (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major vector in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food.
Main article: Human parasite Endoparasites Protozoan organisms Common name of organism or disease Latin name (sorted) Body parts affected Diagnostic specimen Prevalence Source/Transmission (Reservoir/Vector) Granulomatous amoebic encephalitis and Acanthamoeba keratitis (eye infection) Acanthamoeba spp. eye, brain, skin culture worldwide contact lenses cleaned with contaminated tap water ...
T. gondii has been shown to produce a protein called GRA28, released by the MYR1 secretory pathway, which interferes with gene expression in infected cells and results in cells that behave like dendritic cells, becoming highly mobile in the body. [41] Since the parasite can change the host's immune response, it may also have an effect, positive ...
Human parasites are divided into endoparasites, which cause infection inside the body, and ectoparasites, which cause infection superficially within the skin. The cysts and eggs of endoparasites may be found in feces , which aids in the detection of the parasite in the human host while also providing the means for the parasitic species to exit ...