Development of Leishmania (Viannia) panamensis lesions and relationship of numbers of amastigotes to lesion area on antimony-treated and untreated hamsters.

Young adult (60-70-g) male golden hamsters (Mesocricetus auratus) each were injected intradermally at the dorsal base of the tail with 15 x 10(6) promastigotes of Leishmania (Viannia) panamensis (MHOM/PA/83/WR539), and progression and regression of subsequent lesions were evaluated for up to 17 wk postinfection (PI) as to area, weight, and number of amastigotes within lesions in untreated hamsters and in hamsters treated with meglumine antimoniate (Glucantime). In untreated hamsters total area of lesion, weight, and numbers of amastigotes generally increased rapidly and concomitantly up to 3-4 wk PI. Amastigote numbers tended to decrease from 4 to 11 wk PI and subsequently the numbers of amastigotes within the lesions decreased rapidly, whereas relatively little change occurred in the area and weight of the lesions. Meglumine antimoniate treatment of cutaneous hamster lesions resulted in marked concomitant decrease in size of the lesions and numbers of amastigotes within the lesions examined 1 wk after treatment. Measurement of the area of cutaneous leishmanial lesions thus would appear to be a valid method of evaluating the efficacy of promising compounds against L. panamensis in hamsters when measurements are taken 3-5 wk after experimental infection and reflects the number of amastigotes present in the lesion.