A Quantitative Polymerase Chain Reaction (qPCR) Protocol Predictive of Treatment Outcome in Cutaneous Leishmaniasis Caused by Leishmania braziliensis.

Leishmania braziliensis is the most prevalent agent causing cutaneous leishmaniasis (CL) in Brazil. While inflammation is a hallmark of CL, few parasites are found at the lesion site, leading to challenges regarding diagnosis. Using L braziliensis kDNA and human 18S rRNA as targets, the present study developed a quantitative polymerase chain reaction assay to determine parasite load in biopsies from patients with CL who were residing in an endemic area in northeastern Brazil. In addition, we investigated whether parasite load correlated with clinical outcome, and we observed that patients with higher parasite load were more likely to experience therapy failure. Moreover, patients with CL in the early phase of infection presented higher levels of parasite transcripts than individuals in later phases. Thus, our results suggest that parasite load as determined by quantitative polymerase chain reaction may constitute a valuable prognostic tool to aid in the determination of disease severity and treatment outcome.