Abstract
Visceral Leishmaniasis (VL), a life-threating disease in Sudan and Eastern Africa, is usually diagnosed by a painful and invasive tissue aspirate microscopy. This study assessed the diagnostic effectiveness of buffy coat (BC) microscopy and the rK39 immunoassay test separately and combined as an easy non-invasive method applied to peripheral blood sample for field diagnosis of VL. 151 VL suspected patients were recruited from tertiary rural hospitals in Bazura, Gedaref state, from 2014-2015. All patients were tested for VL using rK39 ICT and microscopy smears from LN aspirate and BC in addition to PCR from BC as a reference standard test. Both BC and LN aspirate microscopy showed perfect specificity (100%) with false negative results, while the majority of true positives (81%) had a low-parasite burden. ICT showed almost perfect agreement but limited by its poor specificity. Each of these three tests is inadequate as a consistent single diagnostic tool and should be replaced by PCR in routine practice. Combining the results of risk-free BC microscopy and rk39 ICT, using peripheral blood sample, improved VL diagnosis with almost perfect agreement and 93.4% accuracy. Our findings indicate that combined BC microscopy and ICT are accurate, simple and easy point-of-care VL diagnostic tools in community and rural hospitals that can replace or reduce the use of invasive tissue aspirates microscopy, when PCR is unavailable. This is particularly of value in endemic rural areas, decreasing the delay in final diagnosis and preventing deaths caused by VL.