Comparative evaluation of two flowcytometric analysers as diagnostic tools for the automated detection of malaria

Abstract

Goals: Automated flowcytometric analysers are used to analyse complete blood count (CBC) in most patients. They differentiate WBC depending on their size, internal granularity, and nuclear content by producing various scattergrams. In malaria, haemozoin pigment-containing cells (parasitized RBC and phagocytic cells) are able to depolarize the laser beam and therefore exhibit abnormal scattergram.

Procedure: A study was conducted to evaluate the diagnostic utility and to determine the sensitivity and specificity of flowcytometric haematology analysers [Sysmex XE-2100 (System 1) and Cell-Dyn 3700 (System 2)] in comparison with the conventional microscopy (QBC, AO, Giemsa) and ICT (Immunochromatographic test) for detection of the malaria parasite.

Results: Fifty-eight of 320 samples were found to be positive for malaria by conventional methods. Considering atypical scattergram, System 1 showed the sensitivity and specificity of 68.9% and 90.6%, respectively; whereas System 2 showed a sensitivity of 100% and specificity of 98.8%.

Conclusion: System 2 (Cell-Dyn 3700) was found to be a highly sensitive and specific tool compared to System 1 and conventional methods. Hence, it may be preferred for automated detection of malaria in the blood samples of patients with a differential diagnosis of malaria and those who are subjected to CBC analysis.

Keywords: Quantitative buffy coat assay; flowcytometric analyser; malaria; microscopy; scattergram.