Which species shows a band form trophozoite across the red blood cell in blood smears?

• A. Plasmodium falciparum
• B. Babesia sp.
• C. Plasmodium malariae
• D. Trypanosoma cruzi

Answer: (C)

Recognizing a band-shaped trophozoite spanning the red blood cell points to Plasmodium malariae. On a thin blood smear, the trophozoite of this species often appears as a slender band that stretches across the RBC, a hallmark that helps distinguish it from other malaria parasites. In contrast, Plasmodium falciparum usually shows multiple tiny ring forms per cell and rarely mature trophozoites; Plasmodium vivax and Plasmodium ovale produce enlarged red cells with Schuffner’s stippling; Babesia forms often show the Maltese cross arrangement of merozoites inside red cells; and Trypanosoma cruzi appears as circulating trypomastigotes rather than a band-like trophozoite across an RBC.