Gallery of early trophozoites

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General Comments

This stage effectively runs continuously into the late trophozoite stage: at the very earliest point all trophozoites appear as ring forms, and species differences are very difficult to distinguish, with the "species specific" elements only appearing as they begin to mature. We have tried to illustrate this in the selected images.

It is also worth noting that "species specific" features such as cytoplasmic dots are dependent on stain quality and may not be easily detected if not stained as per recommended protocols (see this page). Also, note that "species-specific" features are never entirely specific: appearances such as double dot forms, multiply infected cells etc. are simply more frequent in some species - for more information see the blue links in the descriptions.

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P.falciparum
Small delicate rings, within red cells of normal (or slightly crenated) appearance.
These may be the only forms seen in some patients at diagnosis.
Some parasite forms are typical though not exclusive of the species, these include: accolé forms, double chromatin dot forms, and multiple parasites within infected red cells. Cytoplasmic dots will not generally be found in early trophozoites.

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  Fine ring form

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  Double dot form and normal ring

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  Accolé and double dot forms

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  Multiple parasite form

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P.vivax
Rings begin as small forms in normal sized red cells, but as they develop both parasites and red cells become markedly enlarged and irregular. Schuffners dots develop during this stage initially as a fine dusting but becoming more prominent.

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  Early ring form

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  Early ring form

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  Intermediate trophozoite

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  Intermediate/late trophozoite

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P.ovale
As with the other species development begins with small forms and normal red cells; However as the species develops cahnges to red cells begin that might include finbriation, ovoid form and some enlargmnet. Similar to P.vivax the cytoplasmic James (Schuffners) dots appear initially as a fine dots but becoming more prominent as the parasites mature.

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  Early ring form

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  Ring with dots/fimbriation

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  faint Ziemann's dots

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  Ring early ovoid change

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P.malariae
Generally parasites are infrequent. The very early small forms become a little more robust than P.falciparum, and may acquire features more typical (though not exclusive) for species including central chromatin dot forms, and early parasite elongation or angular forms. Red cells have normal size and shape or may have reduced size, cytoplasmic dots should not be present (although the uncommon fine Stinton's dots may be seen).

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  Ring form in small red cell

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  The central chromatin dot

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  Early elongation, Stinton's dots

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  Early angularity of form

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P.knowlesi
At the early trophozoite stage an infection by P.knowlesi resembles that by P.falciparum and may include cells that have double chromatin dots, muliply infected red cells, and accolé forms. This may create diagnostic confusion in cases where only early trophozoites are present. Later forms begin to resemple parasites of P.malariae and hese should be specifically sought where infections arise in geographical areas associated with this parasite.

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  Fine early rings

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  Double dot (right)

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  Accolé form

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  Multiple infection

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