Table 3

Comparison between P. knowlesi and P. malariae parasites in human infections

P. malariae*

P. knowlesi

HOST ERYTHROCYTE

Size

Not enlarged

Not enlarged

Shape

Rounded, not distorted

Rounded, generally not distorted

Stippling

Ziemen's stippling under certain staining conditions

Irregular dots or stippling in some erythrocytes with mature trophozoites, schizonts and gametocytes

PARASITE

Early trophozoite (ring form)

Ring form with dense cytoplasm and single chromatin; sometimes with accessory dot

Ring forms are compact with dense cytoplasm; single or double chromatin and rarely triple chromatin; appliqué forms; multiple parasites in single erythrocyte

Late trophozoite

Regular and compact cytoplasm; appearance of pigment

Dense and thick cytoplasm; Cytoplasm slightly amoeboid and irregular; band forms; varying pigmentation

Mature trophozoite

Compact, rounded, heavily pigmented; band forms; not amoeboid

Compact and dense cytoplasm, rounded shape with dark brown pigment; band forms; not amoeboid

Schizont

Occupies whole erythrocyte, contains 6–12 merozoites, usually 8; merozoites clustered around dark-brown malaria pigment forming rosette pattern

Occupies whole erythrocyte; contains up to 16 merozoites; merozoites irregularly scattered or grape-like cluster; malaria pigment scattered or collects into a single mass

Gametocyte

Round, compact, occupies whole erythrocyte, scattered malaria pigment; early forms are very similar to mature trophozoites

Round, compact, fills whole erythrocyte, scattered or clumped malaria pigment; early forms are very similar to mature trophozoites

*Based on descriptions by Garnham [1], Coatney et al [16] and Warrell & Gilles [12].

Lee et al. Malaria Journal 2009 8:73   doi:10.1186/1475-2875-8-73