Evaluation of rK-39 Strip Test Using Urine for Diagnosis of Visceral Leishmaniasis in an Endemic Region of India

Abstract

Abstract. The definitive diagnosis of visceral leishmaniasis (VL) requires invasive procedures for demonstration of parasites in tissue smear or culture. These procedures need expertise and laboratory supports and cannot be performed in the field. The aim of the present study was to evaluate the existing rK-39 immunochromatographic nitrocellulose strips test (ICT) with some modification in human urine for diagnosis of VL. The test was performed on both sera and urine samples on the same 786 subjects (365 confirmed VL and 421 control subjects). The sensitivity of the rK-39 ICT in serum was 100%, whereas the specificity was 93.8%, 100%, and 96.2% in healthy controls from endemic, non-endemic, and other infectious diseases, respectively. However, in urine samples, the test showed 96.1% sensitivity and 100% specificity. Considering sensitivity and feasibility of the test in the field, rK-39 ICT using urine samples can be an alternative to conventional invasive VL diagnosis.

Evaluation of Urine as a Diagnostic Specimen for Visceral Leishmaniasis in Sudan

“…The rk39 test had a sensitivity of 72.1% (95% CI: 57.3-83.3) and a specificity of 76.9% (95% CI: 58.9-88.9) using the initial diagnosis (clinical symptoms combined with positive serology) as reference. The sensitivity of DAT on urine was 62.8% (95% CI: 47.9-75.6) and specificity 69.2% (50.0-83.5).These sensitivities and specificities are lower than those observed on the Indian sub-continent [2][3][4], but are better than those of another urine based diagnostic test, KAtex, in East Africa [7]. The difference between Indian and East African level of specificity and sensitivity could be explained by the heterogeneity of L. donavani strains in East Africa versus their homogeneity in India [7].…”

“…There are several reports, in particular from the Indian subcontinent that describes a good diagnostic performance of rK39 strip tests using urine samples [2][3][4]. In contrast, limited information on testing of urine samples with serology is available from East Africa (Sudan and Ethiopia), another VL hot spot, although it is well known that both tests have an overall good sensitivity and specificity in that particular region when performed on serum samples; DAT: 94.23% and 89.97%, respectively and rK39: 94.48% and 88.75%, respectively [5].…”

To evaluate efficacy and safety of amphotericin B in two different doses in the treatment of post kala-azar dermal leishmaniasis (PKDL)

“…The major drawback is, it becomes positive in treated cases of VL. As regards to noninvasive samples, urine can be used in place of blood and serum in rK39 based strip test for diagnosis of VL, but it has not been tested for PKDL [26]. Slit aspirate is another simple and minimally invasive method showing high sensitivity and specificity with rK39 strip test, however microscopical observation of slit aspirate sample offers low sensitivity (60%) [12].…”

Visceral Leishmaniasis Control and Elimination: Is There a Role for Vaccines in Achieving Regional and Global Goals?

“…Development of more sensitive serological tests shows promise. As an example, the rK39 immunochromatographic test showed excellent diagnostic performance in India and Nepal, 36 and further development and standardization of such an assay should be encouraged. Finally, the possibility to establish a controlled human infection model to accelerate clinical evaluation of VL vaccines was raised.…”