Vaccination and immunity against oriental sore

Abstract 1. 1. Forty-four experimental inoculations were made on thirty-five volunteers using 4 to 50 days old first, second, third or fourth generation cultures of Leishmania tropica. Of these inoculations, thirty-five developed into typical oriental sores (80 per cent.), and nine failed to take. 2. 2. The incubation period of the experimental sores seems to be dependent upon the quantity of inoculum, the depth of inoculation and the individual variability in the degree of susceptibility. 3. 3. A single oriental sore, either experimentally or naturally acquired, confers a definite immunity to inoculation of infective L. tropica culture, and presumably to infection by natural routes. 4. 4. The reaction in immune individuals to the intracutaneous inoculation of L. tropica, with a suitable control, is specific and may be useful as a differential diagnostic procedure in obscure cases of leishmania-like sores in which the presence of parasites may not be demonstrable by culture and staining methods. 5. 5. In view of the ease and innocuousness with which oriental sores can be produced by the method described, we recommend the vaccination of susceptible individuals living in hyperendemic areas with live cultures of L. tropica. This inoculation should be made on an inconspicuous part of the body, so that the subject may be protected against lesions on the face or other exposed parts, and consequent unsightly scarring.