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 - the "species specific" elements only appear as parasites mature.

Notes:
1. Features such as cytoplasmic dots depend on stain quality and are not easily detected if slides are not stained using recommended protocols (see this page).
2."Species-specific" features are never entirely specific: appearances such as double dot forms, multiply infected cells etc. may ve more frequently seen in some species but it is the overall features that count - 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 fimbriation, ovoid form and some enlargement. 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 of P.falciparum and the number of infected cells amy be high. Forms found may also resemble P.falciparum with parasites that have double chromatin dots, multiply infected red cells, or accolé forms. This may create diagnostic difficulty in cases where only early trophozoites are present. Later forms however begin to resemble parasites of P.malariae and these 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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