Thick films - parasites identification: Difference between revisions
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<span style="font-size:90%">Early trophozoite forms (''P.ovale'')</span> | <span style="font-size:90%">'''Early trophozoite forms''' (''P.ovale'')</span> | ||
<gallery mode="nolines" heights=200px widths=200px> | <gallery mode="nolines" heights=200px widths=200px> | ||
File:4 ET_PO.jpg|A|link={{filepath:4 ET_PO_anno.jpg}} | File:4 ET_PO.jpg|A|link={{filepath:4 ET_PO_anno.jpg}} | ||
File:4 LT_PO.jpg|B|link={{filepath:4 LT_PO_anno.jpg}} | File:4 LT_PO.jpg|B|link={{filepath:4 LT_PO_anno.jpg}} | ||
</gallery> | </gallery> | ||
<span style="font-size:90%">The early trophozoites shown on this thick-film image are well preserved with a well defined chromatin dot and cytoplasm; in contrast to many examples the infected red cell has resisted complete lysis allowing its outline to be distinguished and also the frequent (although less well defined) James' dots to be seen (as well as a suggestion of gold/brown pigment). This makes it possible to infer the species as likely to be''P.ovale'' or ''P.vivax'' although a thin film | <span style="font-size:90%">The early trophozoites shown on this thick-film image are well preserved with a well-defined chromatin dot and cytoplasm; in contrast to many examples found on thick films the infected red cell has resisted complete lysis allowing its outline to be distinguished and also the frequent (although less well defined) James' dots to be seen (as well as a suggestion of gold/brown pigment). This makes it possible to infer the species as likely to be ''P.ovale'' or ''P.vivax'' although a thin film would provide much greater diagnostic confidence and is recommended for species identification.</span> | ||
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<span style="font-size:90%">Late trophozoite forms</span> | <span style="font-size:90%">'''Late trophozoite forms''' (''P.vivax'')</span> | ||
<gallery mode="nolines" heights=200px widths=200px> | <gallery mode="nolines" heights=200px widths=200px> | ||
File:4 PV_ET.jpg|link={{filepath:4 PV_ET.jpg}} | File:4 PV_ET.jpg|link={{filepath:4 PV_ET.jpg}} | ||
File:4 LT_PO_dots.jpg|link={{filepath:4 LT_PO_dots_anno.jpg}} | File:4 LT_PO_dots.jpg|link={{filepath:4 LT_PO_dots_anno.jpg}} | ||
</gallery> | </gallery> | ||
<span style="font-size:90%"></span> | <span style="font-size:90%">These examples show slightly better preservation and detection of "species-specific" parasite features, in this case an irregularity of parasite cytoplasm suggests a distortion of the ring associated with infection by ''P.vivax''. This impression is supported by the large size of the parasite compared to the surrounding erythrocyte and by the suggesion of Schuffner's dots in the red cell cytoplasm.</span> | ||
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<span style="font-size:90%">Schizont forms</span> | <span style="font-size:90%">'''Schizont forms'''</span> | ||
<gallery mode="nolines" heights=200px widths=200px> | <gallery mode="nolines" heights=200px widths=200px> | ||
File:4 PO_schizontLT.jpg|link={{filepath:4 PO_schizorLT_anno.jpg}} | File:4 PO_schizontLT.jpg|link={{filepath:4 PO_schizorLT_anno.jpg}} | ||
Revision as of 10:16, 4 March 2025
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Recognising specific parasite features on malaria thick films
In some species and parasite forms the morphology will be better preserved allowing a more confident identification and assignment of either parasite developmental stage, species or associated species. This can vary within the preparation according to the thickness of the preparation and the relative rsistance to lysis. Some examples are given below:
NOTE: the images are at relatively low magnification - to view them properly please click on the image to view in larger annotated form, then use the "back" button on your browser to return to the referring page.
Early trophozoite forms (P.ovale)
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A
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B
The early trophozoites shown on this thick-film image are well preserved with a well-defined chromatin dot and cytoplasm; in contrast to many examples found on thick films the infected red cell has resisted complete lysis allowing its outline to be distinguished and also the frequent (although less well defined) James' dots to be seen (as well as a suggestion of gold/brown pigment). This makes it possible to infer the species as likely to be P.ovale or P.vivax although a thin film would provide much greater diagnostic confidence and is recommended for species identification.
Late trophozoite forms (P.vivax)
These examples show slightly better preservation and detection of "species-specific" parasite features, in this case an irregularity of parasite cytoplasm suggests a distortion of the ring associated with infection by P.vivax. This impression is supported by the large size of the parasite compared to the surrounding erythrocyte and by the suggesion of Schuffner's dots in the red cell cytoplasm.
Schizont forms
Gametocyte forms
Malaria pigment
