Background: It has always been a challenge to increase the concentration of malaria parasites in blood without compromising on specificity. The conventional thick smear method is a good sensitive tool. But the disadvantage is that a lot of expertise and experience is needed to perform this. A pilot study was undertaken to improvise the Quantitative Buffy Coat (QBC) method so that the advantages of both thick and thin smears could be combined.
Methods: Used QBC capillary tubes were washed off the blood and the dye and thoroughly cleaned and dried. The floats were preserved. Blood samples of ten malaria positive patients collected already in EDTA bottles were drawn onto the washed and dried QBC capillaries. The float was re-inserted and centrifugation done as recommended by the QBC manufacturers. The capillary tubes were broken with the aid of a diamond pencil at the area were parasites infested cells were most likely to be seen i.e. just below the buffy coat area. Smears were made onto a slide with this material and stained using the conventional Romanowsky method of staining. Ordinary microscopy was carried out and parasitaemia were quantified as number per oil immersion field and the results were compared with the recorded thin film reports. Five known negative controls were treated similarly.
Results: Parasites number was found to be on an average ten times higher per oil immersion field compared to the conventional methods. Negative controls yielded valid outcomes.
Conclusion: This preliminary study promises to be a useful tool in screening for malaria in endemic areas where resources are limited. It also adds to the specificity compared with the original QBC method. Larger study involving more samples is required to further validate the results. Any easy method (preferably automated) to cut the capillary tube thereby eliminating the risk of infection to the operator would help a long way in making the method more user friendly.HTML PDF
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