P. falciparum and P. knowlesi

Plasmodium falciparum

P. falciparum is commonly associated with severe malaria infection with high parasitic burden.

In the ring form, RBC may have multiple small rings, accole ring forms and double dot ring forms.

Gemetocytes are crecenteric shaped.

Peripheral blood film of a patient with P. faciparum. Note the high parasitic burden with RBC with multiple ring forms, accole ring forms and double dot ring forms.

Plasmodium knowlesi

P. knowlesi is a simian malaria parasite; the natural hosts are macaques.

The blood stages of P. knowlesi resemble P. malariae, while the ring stages resemble P. falciparum

Peripheral blood film of a patient with P. knowlesi. The parasite burden is not high but some RBC has 2-3 ring forms with some accole ring forms seen as well. This is similar to P. falciparum.

Other Resources

• ASH image bank: Diagnosing Plasmodium falciparum in a teenage traveler by peripheral blood smear
• ASH image bank: Falciparum-Gametocytes and Ring stages