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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]
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 ...
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". [12] [13] An endoparasite lives inside the host's body; an ectoparasite lives outside, on the host's surface. [14]
They were once considered protozoans or protists, but are now known to be fungi, [8] or a sister group to true fungi. [9] These fungal microbes are obligate eukaryotic parasites that use a unique mechanism to infect host cells. [7] They have recently been discovered in a 2017 Cornell study to infect Coleoptera on a large scale.
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.
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 ...
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 ...
The parasitophorous vacuole is formed during cell invasion, when the parasite uses part of the membrane of the host cell to form a parasitophorous vacuolar membrane (PVM). The PVM surrounds the intracellular parasite, creating a separate bubble of cytoplasm-filled plasma membrane within the host cell. The rhoptry and the microneme, special ...