Clinical and immunological characteristics of tegumentary leishmaniasis cases in Bolivia

Background Tegumentary leishmaniasis (TL) is a parasitic disease that can present a cutaneous or mucocutaneous clinical form (CL and MCL, respectively). The disease is caused by different Leishmania species and transmitted by phlebotomine sand flies. Bolivia has one of the highest incidences of the disease in South America and the diagnosis is done by parasitological techniques. Our aim was to describe the clinical and immunological characteristics of CL and MCL patients attending the leishmaniasis reference center in Cochabamba, Bolivia, in order to gain updated clinical and epidemiological information, to evaluate the diagnostic methods used and to identify biomarkers related to clinical disease and its evolution. Methodology/Principal findings The study was conducted from September 2014 to November 2015 and 135 patients with lesions compatible with CL or MCL were included. Epidemiological and clinical data were collected using a semi-structured questionnaire. Two parasitological diagnostic methods were used: Giemsa-stained smears and culture of lesion aspirates. Blood samples obtained from participants were used to measure the concentrations of different cytokines. 59.2% (80/135) were leishmaniasis confirmed cases (CL: 71.3%; MCL: 28.7%). Sixty percent of the confirmed cases were positive by smears and 90.6% were positive by culture. 53.8% were primo-infections. Eotaxin and monokine induced by IFN-gamma presented higher serum concentrations in the MCL clinical presentation compared to CL cases and no-cases. None of the cytokines presented different concentrations between primo-infections and secondary infections due to treatment failure. Conclusions/Significance In Bolivia, parasitological diagnosis remains the reference standard in diagnosis of leishmaniasis because of its high specificity, whereas the sensitivity varies over a wide range leading to loss of cases. Until more accurate tools are implemented, all patients should be tested by both smears and culture of lesion aspirates to minimize the risk of false negatives. Our results showed higher concentrations of several cytokines in MCL compared to CL, but no differences were observed between CL and no-cases. In addition, none of the cytokines differed between primary and secondary infections. These results highlight the need of further research to identify biomarkers of susceptibility and disease progression, in addition to looking at the local cellular immune responses in the lesions. Author summary Tegumentary leishmaniasis is a parasitic disease caused by different Leishmania species and transmitted by phlebotomine sand flies. The disease is distributed worldwide and it can present a cutaneous or mucocutaneous clinical form. The clinical outcomes of the disease depend on factors inherent to the parasite, the vector and the host. Bolivia has one of the highest incidences of the disease in South America, where the diagnosis is mainly done by parasitological techniques. The present study was conducted from September 2014 to November 2015 with 135 patients attending the leishmaniasis reference centre in Cochabamba (Bolivia). We aimed to describe the clinical, epidemiological and immunological characteristics of leishmaniasis patients to gain knowledge on tegumentary leishmaniasis and evaluate the suitability of the diagnostic methods used. In South America, Giemsa-stained smears and the culture of lesion aspirates remain the reference standards in diagnosis because of their high specificity, however the sensitivity varies over a wide range resulting in some loss of case detection. Until more accurate tools are implemented, all patients should be screened by both tests to minimize the risk of false negatives. Additionally, for better disease management, identification of biomarkers of susceptibility and disease progression would be desirable.