Monitoring the Long-Term Effectiveness of Miltefosine in Indian Post-Kala-Azar Dermal Leishmaniasis

Abstract

Post-kala-azar dermal leishmaniasis (PKDL), the dermal sequel to visceral leishmaniasis (VL), is characterized by hypopigmented macules (macular) and/or papules and nodules (polymorphic). Post-kala-azar dermal leishmaniasis plays a significant role in disease transmission, emphasizing the need for monitoring chemotherapeutic effectiveness. Accordingly, this study aimed to quantify the parasite burden in PKDL patients after treatment with miltefosine by a quantitative polymerase chain reaction (qPCR). A Leishmania kinetoplastid gene-targeted qPCR was undertaken using DNA from skin biopsy specimens of patients with PKDL at three time points, i.e., at disease presentation (week 0, n = 157, group 1), upon completion of treatment (week 12, n = 39, group 2), and at any time point 6 months after completion of treatment (week ≥ 36, n = 54, group 3). A cycle threshold (Ct) < 30 was considered the cutoff for positivity, and load was quantified as the number of parasites/µg genomic DNA (gDNA); cure was considered when samples had a Ct > 30. The parasite load at disease presentation (group 1) was 10,769 (1,339–80,441)/µg gDNA (median [interquartile range]). In groups 2 and 3, qPCR results were negative in 35/39 cases (89.7%) and 48/54 cases (88.8%), respectively. In the 10/93 (10.8%) qPCR-positive cases, the parasite burdens in groups 2 and 3 were 2,420 (1,205–5,661)/µg gDNA and 22,195 (5,524–100,106)/µg gDNA, respectively. Serial monitoring was undertaken in 45 randomly selected cases that had completed treatment; all cases in groups 2 or 3 had a Ct > 30, indicating cure. Overall, qPCR confirmed an 89.2% cure (as 83/93 cases showed parasite clearance), and the persistent qPCR positivity was attributed to nonadherence to treatment or unresponsiveness to miltefosine and remains to be investigated.

A phase II, non-comparative randomised trial of two treatments involving liposomal amphotericin B and miltefosine for post-kala-azar dermal leishmaniasis in India and Bangladesh

“…All these patients initially responded well to therapy. In studies where qPCR was used to quantify skin parasite load, parasite DNA had all but disappeared at EOT, but was detectable again months to years later when patients relapsed [ 24 ]. The main limitation of this study is that it does not allow a direct comparison of the two treatment arms.…”