Malaria Treatment & Prevention

Hi Raymond,

Thank you for posting this. I agree, and would like to add that where I work
in Zimbabwe, we regularly encounter the same problem. RDTs have been
valuable in their convenience and speed, but problematic in their frequent
discord with our microscopy. This disagreement leaves the clinician with a
perplexing decision. Many of the housestaff will treat empirically
regardless of a negative RDT if they are especially concerned (and after
ruling out other etiologies), but we admittedly have very little knowledge
about threshholds of sensitivity and specificity etc. Any expert advice that
could be provided in this realm would be greatly appreciated.

I hope you are well Raymond. Take care my friend.
Cheers,
-Dan

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Dan Schwarz
Alpert School of Medicine, Brown University
Harvard School of Public Health

Dear Raymond,
We have previously conducted an evaluation of RDTs in a field setting. It is not uncommon to find discordant results 9GE and RDTs. The only way to correctly interpret RDTs results is having the clinical context. RDTs have detect persistent antigenicity in blood for a long time when all the parasites have been cleared (HRP-2) up to 4 weeks.(Kyabayinze DJ, Tibenderana JK, Odong GW, Rwakimari JB, Counihan H: Operational accuracy and comparative persistent antigenicity of HRP2 rapid diagnostic tests for Plasmodium falciparum malaria in a hyperendemic region of Uganda. Malar J 2008, 7:221.). On the other hand QC the slides and find the error rates.
Daniel

Hi--

I don't have any answers, but some more questions:
a) isn't the real problem when the RDT is negative?
b) I assume that the epidemiological context (level of endemicity, season) is important in the "clinical context" -- if so, the discussion started by Prashant on 12/7 might be relevant.
c) There are many RDTs out there -- which ones have the lowest discordance rates?