Safety/Efficacy Trial of Killed Leishmania Vaccine in Volunteers With no Response to Leishmanin

Development of a safe and effective vaccine against leishmaniasis started more than 10 years ago under WHO/TDR supervision. An autoclaved L. major vaccine (ALM) mixed with BCG has been tested in human in Iran, Pakistan and Sudan. Long term follow up of the vaccinees showed no untoward reactions except the skin reaction at the site of injection. The efficacy results of ALM was not satisfactory. In order to enhance immunogenicity of the vaccine, ALM was adsorbed to alum (Aluminum hydroxide). Alum-ALM plus adjuvant showed to induce protection in Rhesus monkeys against cutaneous leishmaniasis and in Languor monkeys against visceral leishmaniasis. Two trials of a single injection of different doses of Alum-ALM mixed with 1/10th of normal dose of BCG was carried out in healthy volunteers from a non endemic area of Sudan. The safety/immunogenicity parameters of the volunteers were closely monitored and the results showed that side effects were minimal and confined to the site of injection in the form of mild local pain, induration and ulceration, all associated with BCG vaccination. The immunogenicity results showed the strongest immune response seen in any Leishmania vaccine trials so far. It seems that this new formulation is an appropriate candidate for further development. Inoculation with live virulent Leishmania to produce a lesion for the purpose of preventing natural infection is known as leishmanization. The induced lesion heals and the person is usually protected against further infections. This method of prevention was practiced for centuries in the region. In this study volunteers with no response to leishmanin will be injected twice (30 days apart) with Alum-ALM 200 ug + 1/10 of BCG (n = 50) or BCG (n = 50) or BCG diluent alone (n = 50) as control. All volunteers will be leishmanized on day 60 post vaccination. In this trial, volunteers are protected either by vaccine or by leishmanization. The leishmanized volunteers will be visited by weekly and the developm