Observations on immunization against cutaneous leishmaniasis in Israel.

Trials of immunization against Leishmania tropica were initiated in the Israel Defense Forces in 1968. The rate of takes has declined gradually over the years. In 1975, 425 soldiers were inoculated with the same strain of L. tropica as that used since 1968; they were examined at three- and six-month intervals after the inoculation, with 291 soldiers undergoing at least one follow-up examination. Only 13.7% developed lesions at the inoculation site, usually between three and six months after the inoculation. Leishmanin tests were performed in 220 soldiers and there were positive reactions in 19.5%. There was a fair correlation between the development of clinical lesions and positive leishmanin tests. A positive leishmanin test, or a typical lesion, or both, was seen in 21.3% of the inoculated soldiers. L. tropica tends to lose its virulence after prolonged storage and multiple passages. A new strain isolated a few months before this trial was used to inoculate 50 soldiers, 31 of whom were followed up. All 31 developed typical lesions at the site of inoculation, most of them within two to four weeks following the inoculation.