The Jordanian Mid Jordan Valley is a classic focus of Leishmania major as revealed by RFLP of 56 isolates and 173 ITS-1-PCR-positive clinical samples

Abstract

The identity of the causative species of cutaneous leishmaniasis (CL) in the endemic Jordanian Mid Jordan Valley (JMidJV) was investigated using the polymerase chain reaction (PCR) amplifying the ribosomal internal transcribed spacer 1 (ITS-1) followed by the restriction fragment length polymorphism (RFLP). The geographical distribution of CL and the usefulness of ITS1 PCR in diagnosis of suspected CL in the study area were also addressed. Over the period from 2004 to 2009, 56 clinical isolates of Leishmania promastigotes and 185 lesion scrapings spotted on filter papers were obtained from suspected CL patients living in the JMidJV, which is divided into northern and southern districts. The majority (67.1%) of patients occurred in the populated eastern part of the southern district. Of the 185 suspected CL patients, 173 (93.5%) were confirmed positive using PCR. Leishmanial DNA was detected in 27 (90%) of 30 patients having clinically atypical lesions of CL and in 60 (92%) of 65 smear- and culture-negative cases having typical lesions of CL. The parasites in all of the 56 isolates and the 173 PCR-positive scrapings were classified as Leishmania major. In conclusion, PCR is useful in diagnosis of CL especially when smear and culture are negative. It is also recommended as a differential diagnostic tool of atypical lesions when CL is endemic. The identification of L. major as the causative species in such a considerable number of CL cases, representative of all mini foci of CL in the study area, shows that the JMidJV is a classic focus of L. major.

Keywords: Cutaneous leishmaniasis; Jordan; PCR diagnosis; Species identification.