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Biology Quiz A Q3: Difference between revisions

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! colspan="1" | Explanation of correct answer (click "Expand")
! colspan="1" | Explanation of correct answer (click "Expand")
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|<span style="font-size:90%">''Short answer taken from section "Microscopy vs RDT" (see the section for full details and links).</br></br>''In ideal conditions a well-trained microscopist with experience in malaria, viewing a well-prepared thick blood film using a good quality microscope may detect with equal or better sensitivity than an RDT test.</span>
|<span style="font-size:90%">''Short answer taken from section "Microscopy vs RDT" (see the section for full details and links).</br></br>''<span style="font-size:90%">(1) The number of replication cycles differs between species: the typical number of merozoites formed differs between species with as few as 8 (in P.malariae) up to a possible 32 (in P.vivax)</br>(2) This stage may not always occur in blood: schizonts of ''P.falciparum'' adhere within the small vessels so is not seen in blood unless infection is very severe
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<span style="font-size:90%">In less ideal conditions where equipment, staining quality, or microscopic experience is less good, then RDTs may have equivalent or superior sensitivity to microscopy (including many malarial endemic regions where microscopy may be unavailable or where the sensitivity of microscopy is limited by training, equipment or facilities). RDTs aso provide a more rapid turnaround time allowing emergency use and rapid decision-making.</span>  
 
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<span style="font-size:90%">For species identification thin films are preferred to thick films or RTDS (including mixed infections), as they also allow more accurate identification of sepecies and the % of infected red-cells (for ''P.falciparum'' or ''P.knowlesi'').</span>
File:Schizontreal4.jpg|Mature schizont releasing merozoites|link={{filepath:Schizontreal4.jpg}}
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<span style="font-size:90%">The progressive maturation of the schizont stage means that they have a wide range of morphological forms (as shown in the diagram at thetop of this page). When the merozoites are released this exposes the body to large amounts of free parasite antigens and can result is an immune response causing high fever and illness symptoms. In some cases the development of parasites is synchronous so that all schizonts mature and release their merozoites at the same time - although rarely seen now, this pattern of development may produce a pattern of remitting fever with a distinct periodicity depending on species: underlying the older descriptive terms tertian or quartan malaria.</span>
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|colspan="1" style = "font-size:90%; color:black|<span style="color:black>[[Biology_Quiz_A_Q4|Go to next question (4 of 5)]]</span>
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Revision as of 10:15, 28 November 2024

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Biology Quiz A Q3


The Schizont developmental stage is the asexual replication stage that some trophozoites follow (others enter sexual development as gametocytes). During this stage the parasite undergoes a number of cycles of division to generate between 8 1n3 32 daughter parasites (1-3 on image) depending on species. The stage ends when the red cell membrane lyses releasing these daughter "merozoites" to enter other red cells (4&5 on image).

Concerning schizonts which statements are correct? (select all true statements)

The stage gives rise to gametocytes
Schizont release causes pyrexia
P.malariae" typically forms 32 merozoites
In P.falciparum they are rarely seen
The stage is morphologically variable


Explanation of correct answer (click "Expand")
Short answer taken from section "Microscopy vs RDT" (see the section for full details and links).

(1) The number of replication cycles differs between species: the typical number of merozoites formed differs between species with as few as 8 (in P.malariae) up to a possible 32 (in P.vivax)
(2) This stage may not always occur in blood: schizonts of P.falciparum adhere within the small vessels so is not seen in blood unless infection is very severe



  • Mature schizont releasing merozoites

    Mature schizont releasing merozoites

The progressive maturation of the schizont stage means that they have a wide range of morphological forms (as shown in the diagram at thetop of this page). When the merozoites are released this exposes the body to large amounts of free parasite antigens and can result is an immune response causing high fever and illness symptoms. In some cases the development of parasites is synchronous so that all schizonts mature and release their merozoites at the same time - although rarely seen now, this pattern of development may produce a pattern of remitting fever with a distinct periodicity depending on species: underlying the older descriptive terms tertian or quartan malaria.

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