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Re-infection of the mosquito: Difference between revisions

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'''Navigation'''</br>
'''Navigation'''</br>
<span style="font-size:80%">(click blue highlighted text to return to page)</span></br></br>
<span style="font-size:90%">>[[Malaria_Index|Main Malaria Index]]''</span></br>
<span style="font-size:90%">[[Malaria Index|Malaria main index]]</span></br>
<span style="font-size:90%">>>[[Malaria_Biology|Malaria Biology Index]]''</span></br>
<span style="font-size:90%">>[[Malaria Biology|Basic malaria biology]]</span></br>
<span style="font-size:90%">>>>Current page: '''Sexual replication'''</span>
<span style="font-size:90%">>>This page: <u>''Re-infection of the mosquito</u></span>
 
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<span style="font-size:160%; color:navy">The initial infection of the host</br></span>
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|colspan="1" style = "font-size:100%; color:black; background: #afbddb |'''Gametogenesis and sexual replication'''
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When a mosquito feeds from a malaria infected host, the blood meal will contain parasites of all forms. Importantly these forms include male and female gametocytes. The pH and temperature changes with the mosquito midgut cause the gametocytes to gain full sexual maturity (gametogenesis). The male gametocyte then undergoes 3 cycles of division to generate 8 male sexual forms (gametes). These then 8 gamaetes then "break out" of the male microgametocytes in a process known as exflagellation, and fuse with the female gamete (derived from the macrogametocyte) then following successful fusion move to the next stage of development with the mosquito gut wall. Finally the parasite enter the salivary glands of the mosquito as sporozoites where a new infection can be initiated.   
When a mosquito feeds from a malaria infected host, the blood meal will contain parasites of all forms. Importantly these forms include male and female gametocytes. The pH and temperature changes with the mosquito midgut cause the gametocytes to gain full sexual maturity (gametogenesis). The male gametocyte then undergoes 3 cycles of division to generate 8 male sexual forms (gametes). These then 8 gametes then "break out" of the male microgametocytes in a process known as exflagellation, and fuse with the female oocyte (derived from the macrogametocyte). Then following successful fusion move to the next stage of development with the mosquito gut wall. Finally the parasite enter the salivary glands of the mosquito as sporozoites where a new infection can be initiated.   


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|colspan="1" style = "font-size:100%; color:black; background: #afbddb |'''Relevance to blood'''
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|colspan="1" style = "font-size:100%; color:black; background: gainsboro |'''Relevance to blood'''
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In stored samples of blood, the changes of storage may partly mimic the conditions within the mosquito midgut leading to changes that would only normally be seen in the mosquito. Some may be difficult to easily recognise, but are clearly atypical in appearance others have very clear appearances of exflagellation. It is important to be able to recognise these forms.
If samples of blood undergo delayed spreading then the changes to pH and temperature caused by storage may partly mimic the conditions within the mosquito midgut leading to changes that would only normally be seen in the mosquito. Some may be difficult to recognise but are clearly atypical in appearance, others such as "exflagellation" have very clear appearances. It is important to be able to recognise these forms as they can cause confusion and mis-diagnosis.


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File:ExFl1.jpg|<span style="font-size:80%">''A''</span>|link={{filepath:ExFl1.jpg}}
 
File:ExFl2.jpg|<span style="font-size:80%">''B''</span>|link={{filepath:ExFl2.jpg}}
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File:ExFl3.jpg|<span style="font-size:80%">''C''</span>|link={{filepath:ExFl3.jpg}}
File:ExFl4.jpg|<span style="font-size:80%"></span>|link={{filepath:ExFl4.jpg}}
File:ExFl4.jpg|<span style="font-size:80%">''D''</span>|link={{filepath:ExFl4.jpg}}
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<span style="font-size:90%">''The gametes of ''P.falciparum'' are seen in the process of exflagellation from  the male gametocyte in a sample that has undergone delayed processing''</span>
<span style="font-size:200%">&#x2192;</span>[[Images of gametocyte development in stored blood|Click for additional clinical images]]


In the initial stage involves both the male microgametocytes and female macrogametocytes swelling and becoming more globular (A) (often clumping together). At this stage they may be difficult to recognise unless you are familiar with the form. The following stages are quite recognisable for the male gametocte as the male gametes burst from the erythrocytes in the process of exflagellation this may be seen as the early emergence (B), red cell swelling and disollution (C) and emergence of the gametes (D).


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Latest revision as of 18:36, 2 November 2024


Navigation
>Main Malaria Index
>>Malaria Biology Index
>>>Current page: Sexual replication


The initial infection of the host


When a mosquito feeds from a malaria infected host, the blood meal will contain parasites of all forms. Importantly these forms include male and female gametocytes. The pH and temperature changes with the mosquito midgut cause the gametocytes to gain full sexual maturity (gametogenesis). The male gametocyte then undergoes 3 cycles of division to generate 8 male sexual forms (gametes). These then 8 gametes then "break out" of the male microgametocytes in a process known as exflagellation, and fuse with the female oocyte (derived from the macrogametocyte). Then following successful fusion move to the next stage of development with the mosquito gut wall. Finally the parasite enter the salivary glands of the mosquito as sporozoites where a new infection can be initiated.



Relevance to blood

If samples of blood undergo delayed spreading then the changes to pH and temperature caused by storage may partly mimic the conditions within the mosquito midgut leading to changes that would only normally be seen in the mosquito. Some may be difficult to recognise but are clearly atypical in appearance, others such as "exflagellation" have very clear appearances. It is important to be able to recognise these forms as they can cause confusion and mis-diagnosis.


The gametes of P.falciparum are seen in the process of exflagellation from the male gametocyte in a sample that has undergone delayed processing


Click for additional clinical images