Leishmanin skin test survey in a focus of high endemicity of Leishmania major in Jordan

Abstract

Cutaneous leishmaniasis (CL) is an endemic disease in Jordan. From 1973 to 1978, a total of 524 cases was reported with almost half of them occurring in the Jordan Valley (Oumeish et al., 1982). In the following years the number of cases recorded from this area has considerably increased. Many subjects were infected in the area of Swaimeh, a small village of about 2000 inhabitants not far from the Jordan River (data from the Ministry of Health). Here, parasites isolated from man and the rodent reservoir Psammomys obesus have been identified isoenzymatically as Leishmania major, agent of zoonotic CL (ZCL) (Saliba et al., 1988). As part of surveillance activities for ZCL in the Jordan Valley, a preliminary survey was carried out among the population of Swaimeh in October 1991, which revealed an impressive prevalence of scars suggestive for past L. major infections. It was thus decided to carry out a leishmanin skin test (LST) in the village in order to obtain epidemetric indices of ZCL. Leishmanin was prepared from the WHO reference strain of L. major (MHOM/SU/73/5-ASKH) according to the techniques and safety procedures described by Gramiccia et al (1990). LST was performed through intradermal injection of 0.1 ml of leishmanin (5 x 105 parasites) and reactions were read 48 h after inoculation by the ball-point pen method (Sokal, 1975). Reactions with an induration size of 5 mm or more were recorded as positive. 399 inhabitants of Swaimeh were carefully examined for the presence of active/past leishmanial lesions and tested with leishmanin. Active lesions were microscopically confirmed. The LST results according to age groups are reported in Table 1. Overall, 350 subjects (87.7%) reacted to the antigen. A positive response was found in 100% of subjects over 5 years. Active leishmanial lesions were found in 8 subjects only (2%), all being LST positive and belonging to age groups from 3 months to 4 years. High correspondence (99.4%) was found between positive LST and presence of active/past lesions.