Malaria is a serious Parasitic infection caused by several different species of plasmodium as plasmodium falciparum, plasmodium vivax, plasmodium ovale, plasmodium malariae (and less commonly by plasmodium knowlesi). The disease presents with symptoms such as anemia, fever, nausea and chills and accounts for a great morbidity and mortality in tropical countries in particular.
How is malaria Diagnosed?
Well malaria is diagnosed by two methods;
One of the methods which is actually the gold standard involves detecting and identifying the parasites in a blood smear. In this method, the laboratory scientist pricks your finger to obtain a small volume of blood which is then smeared onto a glass slide and stained with the appropriate dyes to make the parasites visible under the microscope. This method when properly carried out by an experienced scientist will allow the species of plasmodium causing your malaria to be identified and the numbers of the parasite present in the drop of blood can also be quantified.
The other method which is actually the topic of today’s discussion involves the use of the Malaria Rapid Diagnostic Test (RDT) kit. The commonest malaria RDT kits available in the market today can only detect infections caused by only plasmodium falciparum, which is the commonest plasmodium species found in Africa (it doesn’t mean the other species are absent in Africa). Now here is what you need to know about the malaria Rapid Diagnostic Test:
- A positive RDT results might not mean you HAVE Malaria: You might be surprised by now because there is this widespread misconception among most people that a positive RDT results mean you have malaria parasites in you and should get some medication to take care of that. The truth is that the Malaria RDT kit has been made to detect a particular protein(antigen) of plasmodium falciparumcalled histidine-rich protein II. One fascinating thing about this particular protein (histidine-rich protein II) is that it can persist in the blood for about 28 days even after you have taken antimalarial treatment. So, when the malaria RDT is performed during this period it will turn out positive when actually the parasites has been cleared from the blood by the antimalarial drugs. So, it is often advised (though many don’t follow) that the blood film be examined to confirm the presence of malaria parasites even when Malaria RDT results show ‘positive’. This will prevent you from taking antimalarial drugs at the time you don’t need them (mind you, this can lead to resistance to the antimalarial drugs).
- A negative RDT results might not mean you DON’T HAVE Malaria: As I mentioned earlier, many of the malaria RDT kits available on the market can only detect plasmodium falciparumso a negative test results using such a kit is only indicative that malaria falciparumis absent, but the other species may/may not be present in your blood. So, whenever your malaria RDT results turn out negative you might want to still proceed and do the blood film microscopy to confirm.
- The malaria RDT is not quantitative: what this means is that the test kit cannot tell you the number of parasites in your blood. This makes it difficult for your doctor to know the severity of your infection and how closely you should be monitored.
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