The predictive validity of naturally acquired delayed-type hypersensitivity to leishmanin in resistance to Leishmania major-associated cutaneous leishmaniasis.

To accurately quantify the different outcomes of Leishmania major infection and to evaluate the fraction of zoonotic cutaneous leishmaniasis (ZCL) cases prevented by naturally acquired leishmanin skin test (LST) reactivity, a cohort of 470 children was followed up in 2 endemic foci, Remada and Dhiba, in southern Tunisia. During May 1997, before the ZCL emergence season, LST was performed, and results were reassessed 12 months later. Active case detection during the ZCL emergence season showed a high incidence of ZCL: 57.0% in Remada and 13.7% in Dhiba. The preventive fraction of ZCL conferred by LST reactivity increased proportionally with the reaction size before the emergence season, revealing a dose-response effect of approximately 70%. In addition, asymptomatic L. major infection appeared to be a significant form of natural immunization, particularly in the context of relatively low transmission. These findings may help in the design and evaluation of vaccines.

Random amplified polymorphic DNA technique for identification and differentiation of old world Leishmania species.

The random amplified polymorphic DNA technique may be used to explore parasite DNA polymorphisms. We assessed its applicability to identification of Old World Leishmania species. A set of 6 random decamer primers (Al, A4, A5, A7, A10, and A15) was applied to a panel of DNA from 57 representatives of different Old World Leishmania species. The amplification profiles allowed discrimination among species belonging to different taxonomic complexes. Two criteria were used to analyze the profiles: the presence of consistent amplicons at the same electrophoretic position for isolates of the same species, and the presence of distinct amplicons for isolates of different species. Three primers--Al, A7 and A10--rendered such products.