Evaluation of ICT filariasis card test using whole capillary blood: Comparison with Knott's concentration and counting chamber methods

An immunochromatographic card test (ICT) that uses fingerprick whole blood instead of serum for diagnosis of bancroftian filariasis has recently been developed. The card test was validated in the field in Kenya by comparing i ts sensitivity to the combined sensitivity of Knott's concentration and cou nting chamber methods. A total of 102 (14.6%) and 117 (16.7%) persons was f ound to be microfilaremic by Knott's concentration and counting chamber met hods, respectively. The geometric mean intensities (GMI) were 74.6 microfil ariae (mf)/ml and 256.5 mf/ml by Knott's concentration and counting chamber methods, respectively. All infected individuals detected by both Knott's c oncentration and counting chamber methods were also antigen positive by the ICT filariasis card test (100% sensitivity). Further, of 97 parasitologic ally amicrofilaremic persons, 24 (24.7%) were antigen positive by the ICT. The overall prevalence of antigenemia was 37.3%. Of 100 nonendemic area con trol persons, none was found to be filarial antigen positive (100% specific ity). The results show that the new version of the ICT filariasis card test is a simple, sensitive, specific, and rapid test that is convenient in fie ld settings.