Comparison of Traditional Methods and PCR for Diagnosis of Cutaneous Leishmaniasis in South-West of Iran

The usual method for laboratory diagnosis of cutaneous leishmaniasis was the direct observation of parasites under a light microscope. Although this method has high specificity, it has low sensitivity. The purpose of this study is to compare three methods of direct observation, culture and Mini-exon-PCR to diagnose cutaneous leishmaniasis in Khuzestan province. This study intends to compare sensitivity of PCR approach with sensitivity of the existing traditional methods to diagnose cutaneous leishmaniasis using Mini-exon gene. A total 216 skin biopsies prepared from patients with cutaneous leishmaniasis were studied though direct method, culture in NNN, culture in RPMI 1640 and Mini-exon-PCR and the sensitivity of these methods were compared with each other. In this study Mini-exon-PCR was considered as the gold standard method. Results showed that 46.7% with direct method, 35.1% with culture method in RPMI 1640, 57.8% with culture method in NNN and 70.3% with PCR were positive. Sensitivity was obtained 66.4% for microscopic observation, 50% for culture in RPMI1640, and 82.2% for culture in NNN and 100% for PCR. This study showed that PCR on samples stored in normal saline has higher sensitivity and specificity than other traditional methods (p>0.05). Thus, Mini-exon-PCR on samples in normal saline is a reliable method to diagnose cutaneous leishmaniasis, especially in cases where the diagnosis is negative with the other methods.