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ANNEX 6. Resistance to antimalarials medicines

for early detection of changing patterns of resistance, and suggest where national malaria
treatment policies should be revised. The monitoring procedures available include
therapeutic efficacy testing (also known as in vivo testing). This involves the repeated
assessment of clinical and parasitological outcomes of treatment during a fixed period
of follow-up time to detect any reappearance of symptoms and signs of clinical malaria
and/or parasites in the blood, which would indicate reduced parasite sensitivity with the
particular drug. Other methods include in vitro studies of parasite susceptibility to drugs
in culture and studies of point mutations or duplications in parasite resistance genes with
molecular methods and antimalarial blood concentration measurement.

a6.5.2 reporting of treatment failures

Reports of cases of treatment failure and decreased drug sensitivity have often provided
important first evidence for more widespread resistance in an area. Although such
evidence is subject to bias, it can be collected without much effort at peripheral health
centres. If standardized and registered, such reports can make a valuable contribution
to national early-warning systems; this facilitates cost-effective monitoring by national
programmes.

A6

a6.6 criteria for antimalarial drug policy change

The WHO malaria treatment guidelines recommend that antimalarial treatment policy
should be changed at treatment failure rates considerably lower than those recommended
previously. This major change reflects the availability of highly effective drugs and the
recognition both of the consequences of drug resistance, in terms of morbidity and
mortality, as well as the importance of high-cure rates in malaria control.

It is now recommended that a change of first-line treatment should be initiated if the
total failure proportion exceeds 10%. However, it is acknowledged that a decision to
change may be influenced by a number of other factors; these include: the prevalence and
geographical distribution of reported treatment failures; health service provider and/or
patient dissatisfaction with the treatment; the political and economical context; and the
availability of affordable alternatives to the commonly used treatment.

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