Plasmodium falciparum: Morphology: Difference between revisions
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(Created page with " ---- '''Geographical distribution''' ''P.falciparum'' infection occurs in tropical and subtropical areas of central and South America, Africa, and S.E.Asia; this resembles the distribution of ''P.malariae'' and overlaps but is distinct from the distribution of ''P.vivax'' and ''P.ovale''. Detailed geographical information may be accessed here: [https://malariaatlas.org/explorer/#/]. ---- '''The early trophozoite''' <gallery mode="nolines" widths=200px heights=2...") |
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*Affected red cells have [[Size and shape of infected red cells|normal size]] and haemoglobin content | *Affected red cells have [[Size and shape of infected red cells|normal size]] and haemoglobin content | ||
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Revision as of 13:59, 14 March 2024
Geographical distribution
P.falciparum infection occurs in tropical and subtropical areas of central and South America, Africa, and S.E.Asia; this resembles the distribution of P.malariae and overlaps but is distinct from the distribution of P.vivax and P.ovale.
Detailed geographical information may be accessed here: [1].
The early trophozoite
The earliest developing stage, and often the only form present in this species:
- Ring forms that are fine and delicate
- Frequently the red cells contain multiple parasites
- Parasites may have a distinctive double chromatin dot (signet ring form)
- Parasites may appear on the edge of the red cell and have a flattened appearance (accolé forms)
- Affected red cells have normal size and haemoglobin content
| [[[P.falciparum early trophozoites gallery|Click for gallery]] |
The late trophozoite
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The later developing stage:
- Parasites resemble early ring forms, but thicker and slightly larger
- Additional dots and clefts in cytoplasm when stained correctly (blue and relatively low in number).
- These are Maurer's dots and clefts
- Size and shape of infected red cells usually unaffected, but may become crenated
- Look for double chromatin dot, Accolé forms, multiple parasites/cell
The schizont
The asexual replication stage:
- Do not generally circulate in this species unless overwhelming infection
- Contain multiple asexually formed developing parasites (most frequently 8-16)
- Development is progressive: first there are multiple chromatin dots, later a distinct nucleus and cytoplasm appears
- Loose pigment may be seen in clumps between the parasites
- Red cell size is generally unaffected but haemoglobin will largely be absent (metabolised by the parasites)
The gametocyte
The sexual replication stage (very distinctive).
- Gametocytes are elongated but are also restricted by the red cell membrane
- They appear as straight rods but frequently curve into a “banana form”
- The residual membrane (empty of haemoglobin) may appear as a "blister" to the side of the parasite
- The single chromatin area is in the centre of the parasite, often pigment overlies or surrounds it
- Gametocytes may not be seen in many cases.
Gallery
Click here to see gallery of Plasmodium falciparum forms