Question

Schuffner’s dots occur in
A. Amoeboid trophozoite
B. Signet ring trophozoite
C. Rosette trophozoite
D. Infected RBC

Answer 1

Schuffner’s dots can be defined as a hematological finding that is associated with malaria, exclusively found in infections caused by P. ovale or P. vivax. These dots are fine, round, uniformly red or red-yellow colored after staining with Romanowsky stains.

Complete answer:
Option (A) is incorrect. Schuffner’s dots do not occur in amoeboid trophozoite because these dots are present in the infected RBCs of the host when the host gets infected by a malarial parasite i.e., P. vivax. This amoeboid trophozoite is a developmental stage of P. vivax.
Option (B) is incorrect. Signet ring stage of trophozoite is the early stage of trophozoite development of the malarial parasite in the red blood cell. Schuffner’s dots do not occur in the signet ring trophozoite but these dots occur in the infected RBCs.
Option (C) is incorrect. Rosette trophozoite is a developmental stage of malarial parasite i.e., Plasmodium malariae. In this stage, the schizonts will have 8-10 merozoites that are arranged in a rosette pattern with a clump of pigment in the center.
Option (D) is correct. P. vivax and P. ovale are malarial parasites that produce morphological alterations in the RBCs of the infected host. These infected RBCs when seen under a light microscope after staining the blood smears with Romanowsky stains, showed multiple brick-red dots. These dots were Schnuffner’s dots and hence, it can be concluded that they occur in infected RBCs.

Hence, the correct answer is option (D).

Note: The malarial parasites such as P. vivax and P. ovale are known for producing morphological changes in the RBCs of the infected host. These morphological changes in the RBCs are Schuuffner’s dots that are important for identifying the species of the malarial parasite.