Vaccination against oriental sore by the intracutaneous inoculation of living cultures of Leishmania tropica, advocated by Lawrow and Dubowskoj (1937),1 by Berberian (1939),2 by Senekji and Beattie (1941)3 and by Katzenellenbogen (1942,4 may now be considered as an accepted procedure. Persons who are vaccinated or wish to be vaccinated often ask the question, "When shall we be sufficiently immune against oriental sore to escape infection by natural routes?" To answer this question correctly, I have carried out a number of reinoculations on volunteer subjects at different stages of development of their experimental sores.
EXPERIMENTAL STUDIES
N.N.N. slope cultures of L. tropica were used for all inoculations. The site of inoculation was the anterior aspect of the thigh, about 15 cm. above the kneecap. All inoculations were strictly intracutaneous. The volume of the inoculum was always 0.2 cc. and represented approximately 500,000