Leishmanization: use of an old method for evaluation of candidate vaccines against leishmaniasis.

To establish the safety and reproducibility of live challenge with Leishmania major, a single frozen stabilate was used in two open, single-arm leishmanization (LZ) trials. A total of 42 inoculations in 28 male adult volunteers were followed until complete healing. Lesions induced by LZ are as diverse as natural infection, but much milder. Total protection was seen in 100% (11/11) of recovered volunteers. LZ used as live challenge to test vaccine candidates reduces the required sample size, is cost effective for surrogate markers studies and will induce protection in the participants who are not protected by candidate vaccines.