Failure of a killed Leishmania amazonensis vaccine against American cutaneous leishmaniasis in Colombia

We report the results of a double-blind, randomized, placebo-controlled clinical trial of a killed whole-cell Leishmania amazonensis candidate vaccine against American cutaneous leishmaniasis (CL) in Colombia. The trial subjects were 2597 healthy volunteers with negative leishmanin skin test (LST) selected from rural Colombian soldiers who were going to patrol endemic areas. They were randomized to receive either three doses of vaccine (n = 1295) or placebo In = 1302) given at 20-day intervals. An active and passive case detection system was established to follow-up volunteers for 1 year after vaccination. Safety and efficacy of the vaccine were determined by comparing local and systemic adverse reactions after each dose and the incidence of parasitotogically confirmed CL. In the vaccine and placebo groups 101 (7.7%) and 88 (6.8%) volunteers developed CL respectively. The vaccine was shown to be safe but offered no protection against CL caused by L. panamensis in the proposed vaccination schedule. (c) 2005 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.