## Discriminating Features: *P. vivax* vs *P. falciparum* **Key Point:** Schüffner's dots (also called Schüffner's stippling) are fine, diffuse cytoplasmic dots visible in RBCs infected with *P. vivax* on Giemsa-stained blood smears. These are **absent in *P. falciparum*** and represent the most reliable morphological discriminator on routine blood smear examination. ### Morphological Comparison Table | Feature | *P. vivax* | *P. falciparum* | | --- | --- | --- | | **Schüffner's dots** | Present (fine, diffuse) | Absent | | **RBC size** | Enlarged (1.5–2× normal) | Normal or slightly enlarged | | **RBC shape** | Distorted, irregular | Preserved | | **Maurer's clefts** | Absent | Present (coarse stippling) | | **Gametocyte shape** | Round/oval | Banana/crescent-shaped | | **Ring trophozoites** | Single chromatin dot | Often two chromatin dots | ### Clinical Pearl **High-Yield:** Schüffner's dots are an electron microscopy finding (knob-like projections on RBC membrane) but become visible on light microscopy as cytoplasmic stippling in *P. vivax*. This feature is the **gold standard discriminator** on peripheral smear and is tested frequently in NEET PG. ### Why Schüffner's Dots Matter - They indicate *P. vivax* infection with ~95% specificity - Their absence effectively rules out *P. vivax* and favours *P. falciparum* - They are visible on **routine Giemsa staining** without special techniques - Maurer's clefts (seen in *P. falciparum*) are coarser and less consistent than Schüffner's dots **Mnemonic:** **S**chüffner = **V**ivax (both have 'V' sound); **M**aurer = **F**alciparum (coarse clefts in *F*alciparum) [cite:Baveja 6e Ch 45]
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