Page 9 - 80 guidelines for the treatment of malaria_opt

Glossary

Ring stage. Young usually ring-shaped intra-erythrocytic malaria parasites, before
malaria pigment is evident under microscopy.

Schizonts. Mature malaria parasites in host liver cells (hepatic schizonts) or red blood
cells (erythrocytic schizonts) that are undergoing nuclear division. This process is called
schizogony.

Selection pressure. Resistance to antimalarials emerges and spreads because of the
selective survival advantage that resistant parasites have in the presence of antimalarials
to which they are resistant. Selection pressure describes the intensity and magnitude
of the selection process; the greater the proportion of parasites in a given parasite
population exposed to concentrations of an antimalarial that allows proliferation of
resistant, but not sensitive parasites, the greater the selection pressure.
Severe anaemia. Haemoglobin concentration of < 5 g/100 ml (haematocrit < 15%).

Severe falciparum malaria. Acute falciparum malaria with signs of severity and/or
evidence of vital organ dysfunction.
Sporozoites. Motile malaria parasites that are infective to humans, inoculated by a
feeding female anopheline mosquito. The sporozoites invade hepatocytes.

Transmission intensity. The intensity of malaria transmission measured by the frequency
with which people living in an area are bitten by anopheline mosquitoes carrying
sporozoites. This is often expressed as the annual entomological inoculation rate (EIR),
which is the number of inoculations of malaria parasites received by one person in one
year.

Trophozoites. Stage of development of the malaria parasites within host red blood
cells from the ring stage and before nuclear division. Mature trophozoites contain visible
malaria pigment.
Uncomplicated malaria. Symptomatic infection with malaria parasitaemia without signs
of severity and/or evidence of vital organ dysfunction.

Vectorial capacity. Number of new infections the population of a given vector would
distribute per case per day at a given place and time, assuming conditions of non-
immunity.

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