Plasmodium falciparum: Morphology

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Morphology of Plasmodium falciparum
(See Malaria Biology pages for an explanation of these stages)

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The early trophozoite

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The earliest growth stage, this is characterised by fine ring forms with few other changes to red cell or parasite.

• Ring forms are fine and delicate and may be the sole form present (synchronicity)
• Frequently the red cells contain multiple parasites
• Parasites may have a distinctive "double dot" or signet ring form
• Parasites may appear on the accolé forms that appear flattened against the cell membrane
• Affected red cells have normal size and haemoglobin content

GALLERY

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The late trophozoite

The late trophozoite

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The later growth stage of trophozoites where parasites modification of the erythrocyte is seen with characteristic added dots and possible minor changes to red cell form:

• Parasites resemble early ring forms, but are thicker and may be slightly larger
• Additional blue/grey dots and clefts are seen in red cell cytoplasm when stained correctly
• These dots have low number a characteristic "dot" or "line" form Maurer's dots and clefts
• Size and shape of infected red cells is usually unaffected, but may become crenated
• The double dot, accolé, and multiple parasite forms remain present

GALLERY

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The schizont

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• File:PFS-main image 2.jpg

The schizont is the asexual form of the malaria parasite in blood - for a detailed description see the "Biology of malaria" section in the main menu:

• Do not generally circulate in this species unless overwhelming infection
• The merozoites cluster "untidily" as they develop
• Schizonts develop progressively to form 8-16 merozoites when mature
• In this species the loose malaria pigment may be seen in clumps between the parasites
• Red cell size is generally unaffected but red cells become pale as haemoglobin is metabolised by the parasites

→Click for P.falciparum schizont gallery

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The gametocyte

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• File:PFG-main image.jpg

The sexual replication form (very distinctive).

• male and femaie gametocytes are elongated and have the appearance of rods
• They parasites are rod shaped but the membrane may cause them to curve into a “"banana" form”
• The residual membrane (empty of haemoglobin) is often seen as a "blister" to the side of the parasite
• The single chromatin area is in the centre of the parasite, often has pigment overlying it
• Gametocytes may not be be seen, or may be the only form present (particularly after treatment)

→Click for P.falciparum gametocyte gallery

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