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Evaluation of ICT filariasis card test using whole capillary blood: comparison with Knott's concentration and
1Centre for Clinical Research, Kenya Medical Research Institute, Nairobi.
Insights
A new immunochromatographic card test (ICT) for bancroftian filariasis diagnosis using whole blood demonstrated 100% sensitivity and specificity in field validation. This rapid test is suitable for convenient use in endemic areas.
Area of Science:
- Tropical Medicine
- Infectious Diseases
- Diagnostic Technologies
Background:
- Bancroftian filariasis diagnosis traditionally relies on methods requiring serum or complex procedures.
- A need exists for rapid, sensitive, and specific field-deployable diagnostic tools.
Purpose of the Study:
- To validate a newly developed immunochromatographic card test (ICT) for diagnosing bancroftian filariasis using fingerprick whole blood.
- To compare the ICT's performance against established parasitological methods (Knott's concentration and counting chamber).
Main Methods:
- Field validation of the ICT filariasis card test in Kenya.
- Comparison of ICT results with Knott's concentration and counting chamber methods for microfilaremia detection.
- Assessment of ICT sensitivity and specificity using parasitological and antigenemia data.
Main Results:
- The ICT demonstrated 100% sensitivity, correctly identifying all individuals positive by both Knott's and counting chamber methods.
- The ICT showed 100% specificity, with no positive results in non-endemic control individuals.
- A significant proportion (24.7%) of parasitologically amicrofilaremic individuals were antigen positive by ICT, indicating a 37.3% overall antigenemia prevalence.
Conclusions:
- The ICT filariasis card test is a simple, sensitive, specific, and rapid diagnostic tool.
- The test's convenience with fingerprick whole blood makes it highly suitable for field settings in bancroftian filariasis surveillance and diagnosis.
Abstract:
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 its sensitivity to the combined sensitivity of Knott's concentration and counting chamber methods. A total of 102 (14.6%) and 117 (16.7%) persons was found to be microfilaremic by Knott's concentration and counting chamber methods, respectively. The geometric mean intensities (GMI) were 74.6 microfilariae (mf)/ml and 256.5 mf/ml by Knott's concentration and counting chamber methods, respectively. All infected individuals detected by both Knott's concentration and counting chamber methods were also antigen positive by the ICT filariasis card test (100% sensitivity). Further, of 97 parasitologically amicrofilaremic persons, 24 (24.7%) were antigen positive by the ICT. The overall prevalence of antigenemia was 37.3%. Of 100 nonendemic area control persons, none was found to be filarial antigen positive (100% specificity). 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 field settings.