Drug-Resistant Malaria - libdoc.who.int - World Health Organization

MONITORING / 45
table time 1ag and cannot be expected to replace the investigators'
immediate analysis of their own results.
Guidelines for Samp1in~
In principle, the selection of cases for study should follow
the basic precepts for the selection of a statistically valid
sample. However, it is appreciated that the prevalence of
suitable positive cases for testing in a particular study area may
make the application of this process difficult or impossible.
The population to be investigated needs to be
specified in accordance with the objectives of
Appropriate population groups might be:
selected and
the study.
inhabitants of a given geographical area at a given time;
labourers and migrants
geographical area;
in camps within a given
migrants, domestic and internat iona1, between spec ified
areas (indicate also routes of migration);
others.
(a) Is confirmed resistance present or are there reports on
the lack of clinical response ("resistance" being defined in terms
of the test, e.g. growth of schizonts in the presence of 1.5 n-mo1
(== 1.5 x lO-6M/l) or more of chloroquine in the macro in vitro
test, and 5.7 p-mo1 (==1.14 x 10-6M/1) in the micro rn-~
test)?
(b) Does the frequency of resistance reach a certain level
and distribution at which some specific decision may be called for
(e.g. change to alternative drug(s) or drug combinations,
introduction of intensive vector control measures, etc.)?
(c) What is the response of the parasite to the drug (in the
popu1at ion)?
(d) Was the
significantly from
same population?
response of the parasite to the drug
that observed in earlier investigations
!sti~ate_of the Required Sa~p1e Size
changed
of the
It is appreciated that the estimation supposes that the sample