Detection of DNA from Leishmania (Viannia): accuracy of polymerase chain reaction for the diagnosis of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) can occur in skin and mucosa, causing disfiguring lesions. The laboratory diagnosis of CL involves immunological methods and optical detection of the parasite, al of which have limitations. There is a need for more effective diagnostic methods for CL which wil allow treatment to be initiated more promptly in order to help prevent the development of severe forms of mucosal disease, and to estimate the prognosis of the infection. The polymerase chain reaction (PCR) has been widely used to diagnose CL, because of its higher sensitivity. This study estimated the accuracy and compared PCRs of samples from lesion scarification (PCR-L) and blood sample-enriched leukocytes (PCR-B) with three conventional diagnostic techniques: parasite direct search (DS), Montenegro skin test (MST), and indirect immunofluorescence reaction (IIF). The study included 276 patients under suspicion of CL. We conducted a cross-sectional study, in which patients were selected by convenience sampling. We used MP3H/MP1L primers to generate a Leishmania (Viannia) (minicircle kDNA) fragment of 70-bp. Of 106 patients with CL, 83.87%, 51.67%, 64.52%, 85.71%, or 96.10% tested positive by PCR-L, PCR-B, DS, IIF, or MST, respectively. Five patients tested positive only by PCR-L, and two other patients only by PCR-B. PCR-L is indicated for use in patients with chronic lesions or Leishmania reinfection, which may progress to mucosal lesion. PCR-B is indicated for use in patients with negative results in conventional tests or for patients with no apparent lesion. PCR is not only useful in diagnosing CL but also helps to identify the infecting species.