A randomised, double-blind, controlled trial of a killed L. major vaccine plus BCG against zoonotic cutaneous leishmaniasis in Iran

Abstract

Safety and efficacy of killed (autoclaved) L. major promastigotes, ALM, mixed with BCG against zoonotic cutaneous leishmaniasis was tested in healthy volunteers (n=2453) in a randomized double blind trial vs. BCG as control. Side-effects were similar in both groups but tended to be slightly more frequent and prolonged in the ALM+BCG group. Leishmanin skin test conversion (induration ≥5 mm) was significantly greater in the ALM+BCG than in the BCG group (36.2% vs. 7.9% on day-80 and 33% vs. 19%, after 1 year, respectively). Cumulative incidence rates for 2 years, were similar in both groups (18.0% vs. 18.5%). However, LST responders on day 80 (≥5 mm) had a significantly lower incidence (35%) of CL during the first year than non-responders. A single dose of ALM+BCG is not sufficiently immunogenic to provide a measurable response when compared to BCG alone. A single dose of this vaccine has been shown to be safe with no evidence of an exacerbating response following natural infection; hence, multiple doses or other adjuvants should be considered to increase its immunogenicity.