Identification of patients with Cutaneous Leishmaniasis using microscopic observation and PCR methods

Leishmaniasis is endemic in more than 88 countries and threatens more than 350 million people. Until recently, diagnosis was based primarily on clinical symptoms and microscopic observation of parasites in stained tissue smears.PCR methods using either genomic or kinetoplast DNA (kDNA) are now frequently used as the most sensitive test for screening the suspected patients of cutaneous Leishmaniasis. In this study, we calculated the sensitivity, specificity, positive and negative predictive value of microscopic observation in diagnosis of cutaneous Leishmaniasis compared with the PCR technique as the gold standard.
Skin biopsies stored in ethanol from 45 patients with suspected cutaneous Leishmaniasis (CL) were tested in a polymerase chain reaction (PCR) assay as the gold standard. Then the sensitivity, specificity, positive and negative predictive value of conventional diagnostic method of microscopic observation of Giemsa stained smears were calculated.
The sensitivity, specificity, positive and negative predictive value of conventional diagnostic method of microscopic observation was 71%, 100%, 100% and 71.9%, respectively.
Conclusion The PCR technique has the more ability in distinguishing healthy subjects from patients than microscopic observation of Giemsa stained smears.