**Figure 3.**

*(5) Howell Jolly body (in a 36-year-old lady with sickle cell disease).*

some level of knowledge and experience. Several species of *Plasmodium* spp. exist. *Plasmodium* spp. may exist in different forms such as ring forms (trophozoites), gametocytes and schizonts. *Babesia* spp. appear in small ring forms (like *Plasmodium falciparum*) but schizonts and gametocytes are not formed [1, 21]. Unlike *Plasmodium* spp., *Babesia* spp. do not produce pigments. However, *Babesia* spp. may appear in groups outside the erythrocyte. Clinical history and travel history is also helpful in differentiating the two parasites. Other red cell inclusions such as Heinz bodies and haemoglobin H inclusions can only be appreciated with supravital staining (reticulocyte preparations). Heinz bodies are denatured haemoglobin (seen in oxidant injury, G6PD deficiency). Haemoglobin H inclusions are seen in alpha-thalassemias giving rise to the characteristic 'golf ball' appearance of the erythrocytes [1, 11, 12].

Rouleaux formation refers to stacking of red cells like coins in a single file. Rouleaux is seen in hyperproteinaemias. Elevated plasma fibrinogen or globulins reduces the zeta potential (repulsive force) between circulating red cells, facilitating their stacking effect. Rouleaux is associated with myeloma/paraproteinaemias, other plasma cell disorders as well as B cell lymphomas. On the other hand, agglutination refers to clumping or aggregation of red cells into clusters or masses and is usually antibody mediated [1]. Agglutination of red cells may be seen in cold haemagglutinin disease and Waldenstrom's macroglobulinaemia [1, 11]. Agglutination is associated with falsely reduced red cell count and high MCV. Pre warming the specimen with heating block helps to disperse the red cells prior to making of a blood smear and automated cell counts.
