Comparison of the quantitative buffy coat technique with the conventional thick blood film technique for malaria case detection in the field

The quantitative buffy coat (QBC) technique was compared with the conventional thick blood film technique in a malaria survey carried out in a mesoendemic area of malaria in Betau, Pahang, Malaysia. The QBC technique was found to be a rapid technique but had a sensitivity of about 56% and a specificity of 95%, using the thick blood film method as the "gold standard". Malaria species identification was unsatisfactory with the QBC technique as it could identify parasites correctly in only about 60% of specimens. It was unable to detect as positive about 58% of specimens which had parasite counts < or = 500 per ul but could detect about 94% of those with counts > 500 per ul. This difference in positive detection rate was significantly different (p < 0.05). It cannot quantify parasitemia easily and the specimens cannot be stored for future reference and for quality control purposes. It is therefore concluded that the QBC technique cannot replace the classical thick blood film technique for use in malaria control programmes. Its use may be appropriate in situations like busy blood banks and outpatient clinics where rapid screening of malaria infection is needed but where experienced malaria microscopists may not be available.