RESUMEN
Leishmania species were isolated from 14 patients with acute cutaneous leishmaniasis [CL] in Shiraz. The isolated organisms were injected subcutaneously into the base tail of 14 groups of Swiss outbred white mice. Each group consisted of 10 mice and each mouse received 2xl0 promastigotes. During 4-6 weeks after inoculation, smears and cultures were taken from this site and the isolated organisms were inoculated into a new series of mice. During 6-8 weeks after inoculation, erythema was observed in only two groups of these animals. No ulceration or open lesion, which are characteristics of L. major, were noticed in the inoculated mice. Upon direct smear preparation from these two groups of animals only a few organisms were seen with no growth in cultures. On the basis of these observations we concluded that the Leishmania isolated from the patients with acute CL in Shiraz is Leishmania tropica. Various factors which contribute to the survival of the organisms at the site of inoculation without formation of open lesions are discussed