Monitoring of Parasite Kinetics in Indian Post–Kala-azar Dermal Leishmaniasis

Background: The potential reservoirs of leishmaniasis in South Asia include relapsed cases of visceral leishmaniasis (VL), patients with post-kala-azar dermal leishmaniasis (PKDL), and an asymptomatically infected population. Therefore, assessment of cure in terms of parasite clearance, early detection of PKDL, and asymptomatic VL are pivotal for ensuring elimination. This study aimed to monitor the efficacy of miltefosine and liposomal amphotericin B (LAmB) in PKDL based on parasite load. Methods: Patients with PKDL were recruited from the dermatology outpatient departments or during active field surveys. Skin biopsies were collected at disease presentation, immediately at the end of treatment, and 6 months later. The presence of parasite DNA was assessed by internal transcribed spacer-1 polymerase chain reaction, and quantified by amplification of parasite kinetoplastid DNA. Results: At disease presentation (n = 184), the median parasite load was 5229 (interquartile range [IQR], 896-50898)/μg genomic DNA (gDNA). Miltefosine cleared the parasites to <10 in the macular (n = 17) and polymorphic (n = 21) variants, and remained so up to 6 months later (<10 parasites). LAmB reduced the parasite burden substantially in macular (n = 34; 2128 [IQR, 544-5763]/µg gDNA) and polymorphic PKDL (n = 36; 2541 [IQR, 650-9073]/µg gDNA). Importantly, in patients who returned 6 months later (n = 38), a resurgence of parasites was evident, as the parasites increased to 5665 (IQR, 1840-17067)/µg gDNA. Conclusions: This study established that quantifying parasite load is an effective approach for monitoring patients with PKDL, wherein miltefosine demonstrated near-total parasite clearance and resolution of symptoms. However, in cases treated with LAmB, the persistence of parasites suggested treatment inadequacy. This needs immediate redressal in view of the leishmaniasis elimination program targeted for 2020.