Value of the quantitative buffy coat capillary tube test (QBC) in the microscopic diagnosis of bancroftian filariasis.

The diagnostic performance of the commerical quantitative buffy coat capillary tube technique was compared with the standard diagnosis of filariasis by microscopical examination of Giemsa stained thick blood films. The comparison was conducted among 83 subjects. The QBC test was highly sensitive than the thick blood film in detection of microfilaraemic patients. The percentage of positive cases among 35 subjects with fever and enlarged lymph nodes in the axilla or in the groin was 48.6% versus 42.8% by thick blood film. The sensitivity was 94.4% versus 83.3% in 18 subjects with lymphatic varices or hydrocele. The sensitivity of the QBC capillary tubes was poor (20%) versus 6.6% among 30 filarial patients with different degrees of lymphatic edema. It is concluded that the QBC capillary test is very simple, rapid and convenient as a diagnostic method for microfilaraemic patients but not suggested to be used neither in the quantitation of the parasite numbers or in species identification.