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Guidelines for the treatment of malaria – 2 edition

Malaria pigment (haemozoin). A dark brown granular pigment formed by malaria
parasites as a by-product of haemoglobin catabolism. The pigment is evident in mature
trophozoites and schizonts. They may also be present in white blood cells (peripheral
monocytes and polymorphonuclear neutrophils) and in the placenta.

Merozoites. Parasites released into the host bloodstream when a hepatic or erythrocytic
schizont bursts. These then invade the red blood cells.

Monotherapy. Antimalarial treatment with a single medicine (either a single active
compound or a synergistic combination of two compounds with related mechanism
of action).

Plasmodium. A genus of protozoan vertebrate blood parasites that includes the causal
agents of malaria. Plasmodium falciparum, P. malariae, P. ovale and P. vivax cause malaria
in humans. Human infections with the monkey malaria parasite, P. knowlesi have also
been reported from forested regions of South-East Asia.

Pre-erythrocytic development. The life-cycle of the malaria parasite when it first
enters the host. Following inoculation into a human by the female anopheline mosquito,
sporozoites invade parenchyma cells in the host liver and multiply within the hepatocytes
for 5–12 days, forming hepatic schizonts. These then burst liberating merozoites into the
bloodstream, which subsequently invade red blood cells.
Radical cure. In P. vivax and P. ovale infections only, this comprises a cure as defined
above plus prevention of relapses by killing hypnozoites.
Rapid diagnostic test (RDT). An antigen-based stick, cassette or card test for malaria
in which a coloured line indicates that plasmodial antigens have been detected.

Recrudescence. The recurrence of asexual parasitaemia after treatment of the infection
with the same infection that caused the original illness. This results from incomplete
clearance of parasitaemia due to inadequate or ineffective treatment. It is, therefore,
different to a relapse in P. vivax and P. ovale infections, and it differs from a new infection
or re-infection (as identified by molecular genotyping in endemic areas).

Recurrence. The recurrence of asexual parasitaemia following treatment. This can be
caused by a recrudescence, a relapse (in P. vivax and P. ovale infections only) or a new
infection.

Relapse. The recurrence of asexual parasitaemia in P. vivax and P. ovale malaria deriving
from persisting liver stages. Relapse occurs when the blood stage infection has been
eliminated but hypnozoites persist in the liver and mature to form hepatic schizonts.
After variable intervals of weeks to months, the hepatic schizonts burst and liberate
merozoites into the bloodstream.

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