Promising prognostic factors in Cutaneous Leishmaniasis in regions of Leishmaniavirus 1 circulation

ABSTRACT Background Cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) may involve parasite dissemination from the primary skin lesion to clinically healthy mucosal sites, a process potentially relevant to the development of mucosal leishmaniasis. Parasite burden and Leishmania RNA Virus 1 (LRV1) have been proposed as factors influencing parasite persistence, dissemination, and treatment response. We investigated whether parasite load and LRV1 detection in skin lesions were associated with Leishmania in clinically healthy nasal mucosa and, in a subset of patients, with therapeutic outcome. We also assessed the relationship between LRV1 and parasite load. Methodology/Principal findings We conducted a prospective observational cohort study. Parasite load and LRV1 were assessed by qPCR in skin lesions and clinically healthy nasal mucosa from patients with localized cutaneous leishmaniasis in Rondonia, Brazilian Amazon. Samples were evaluated before treatment (D0), at the end of treatment (D20), and during follow-up (D90-180). Among 178 patients screened, CL was confirmed in 113. LRV1 was detected in skin lesions in 34.51% of patients and in nasal mucosa in 24.13%. Leishmania DNA was detected in clinically healthy nasal mucosa in 12.38% of patients. LRV1 detection in the skin lesion was associated with detection of Leishmania in the nasal mucosa. Higher parasite loads were observed in more recent lesions. Among patients evaluated for therapeutic outcome, higher parasite load before treatment was associated with treatment failure and was the factor most strongly associated with an unfavorable response in multivariate analysis. Conclusions/Significance LRV1 detection in cutaneous lesions was associated with Leishmania in clinically healthy nasal mucosa, although the significance of this association and its relationship with parasite dissemination require further investigation. In contrast, parasite burden was associated with therapeutic outcome, with higher pre-treatment loads observed in patients who experienced treatment failure. The absence of an association between LRV1 and parasite load suggests that these two parameters may provide distinct information regarding parasite detection at mucosal sites and therapeutic response.