Page 116 - Invited Paper Session (IPS) - Volume 2

IPS186 Fagbamigbe, A. F.
Mouatcho et al. found that the specificities, sensitivities, numbers of false
positives, numbers of false negatives and temperature tolerances of the RDTs
vary considerably and are some of the challenges facing the accuracy of RDTs
[16]. Other factors that may influence diagnostic accuracies are the efficiency
of RDT storage, transport or handling of malaria RDTs as well as the expertise
of the handlers [7] but these factors are not available for assessment in the
current study.
Malaria RDTs are generally designed to be used in malaria-endemic areas
where good-quality microscopies are out of reach. It is a requirement that a
diagnostic method must be accurate and available at the point of care if the
effective diagnosis of all malaria cases is to be achieved. A diagnostic test with
a high degree of sensitivity usually has a low false negative rate which ensures
that only a few true cases are not correctly classified. It is therefore imperative
that a screening test used in ruling out cases should have a reasonably high
degree of sensitivity. In the same vein, a diagnostic test with a high degree of
specificity produces low false positive rates which invariably leads to only a
few misdiagnosed subjects. A confirmatory test used in ruling-in cases should
have a high degree of specificity.
There is a need to adhere to the WHO recommendations on the
procurement of malaria RDTs [7] as well as on the storage and use of malaria
RDTs. Total adherence to these recommendations will substantially improve
the discriminatory and predictive accuracy of the malaria RDTS. According to
the WHO, to be reliable, “RDTs should be sensitive enough to reliably detect
malaria parasites at densities associated with disease” [28]. This suggests that
sensitivity of an RDT is a function of the quality of manufacture, species,
number, viability, and strain of parasites present, RDT conditions, storage
conditions, application technique and level of care exercised. The WHO
recommendation stated further that choice of RDT must be guided by the
panel detection score (PDS) against the Plasmodium falciparum (Pf) and
against the Plasmodium vivax (Pv) which must be at least 75% in both cases
and that the false positive rates and invalid rate should be less than 10% and
5% respectively [7]. For RDTs to perform optimally, there must be a
demonstration of the presence of parasitemia, efficient mechanism for quality
control, "cool chain" for transport and storage, adequately trained health
worker and, adequate monitoring [7].

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