Testing urine samples with rK39 strip as the simplest non-invasive field diagnosis for visceral leishmaniasis: An early report from eastern India

Background: Diagnosis of visceral leishmaniasis (VL) is a major obstacle in the control of this disease. The rK39 strip-test using patient's blood is a breakthrough; however, it still requires a blood sample, which is a concern for safety in the field. We tried to simplify the test using the patient's urine instead of blood. Aims: To observe the sensitivity and specificity of the urine test in comparison with the blood test. Materials and Methods: We tested active and post-treatment VL patients, Post Kala azar dermal leishmaniasis (PKDL), VL/HIV and control subjects (healthy, disease suspects and diseased other than VL) with the rK39 strip-test using blood and urine samples. Statistical Analysis: The level of agreement between the urine and blood testing was calculated by inter-rater agreement (kappa) statistics. Results: Forty-two active VL, 40 treated VL, six PKDL, three VL/HIV and 139 controls (54 healthy, 21 disease suspects and 64 diseased other than VL) were tested. All VL-related cases showed positive results with urine as well as blood samples (100%). The urine testing was found to have 100% sensitivity and 86.33% specificity for the diagnosis of VL. Kappa statistic between the two methods was 0.916 (P<0.001). Urine testing had more false-positive results in comparison with blood testing (13.67% vs. 9.45%), but the test subjects were from VL-endemic areas and they might be exposed to Leishmania donovani infection. Conclusions: The present study has the potentiality of providing a new, yet simplest non-invasive screening tool for VL in remote rural areas.