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nd
Guidelines for the treatment of malaria – 2 edition

Figure A6.2 Effectiveness of artesunate plus mefloquine combination
on parasite levels and resistance

Total parasites
10 12
m
10 10 Drug concentration

Detection limit
10 8
n
10 6 x

A
10 4 y

10 2
B B 1
0
0 1 Weeks 2 3 4

Note: The artesunate plus mefloquine combination. If no artesunate is given, then the number of
parasites exposed to mefloquine alone is given by the area of A; with the combination administered
for 3 days the number of parasites exposed to mefloquine alone is given by the area of B (100
million times fewer). Furthermore, mefloquine levels are higher (m to n) when confronting B than
when confronting the same number of parasites (B1) if no artesunate is given (x to y). If a parasite
containing a de novo mefloquine-resistant mutation were to occur, then such a parasite should
still be susceptible to artesunate. Thus, the probability of selecting a resistant mutant is reduced by
100 million times; as only a maximum of 100 000 parasites are exposed to mefloquine alone after
the fourth day (i.e. in the third cycle), and any artesunate-resistant parasite selected by artesunate
initially would always be killed by the accompanying mefloquine. As a result, the combination is
more effective, reduces transmission and prevents the emergence of resistance to both drugs.

a6.5 monitoring of antimalarial drug resistance

a6.5.1 monitoring methods

The rapid spread of antimalarial drug resistance over the last few decades has increased
the need for monitoring in order to ensure proper management of clinical cases, allow
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