Evaluation of chemotherapy of American leishmaniasis by the indirect fluorescent antibody test.

Evaluation of the effectiveness of treatment of American cutaneous/mucocutaneous leishmaniasis is difficult because dramatic clinical improvement and apparent complete healing can be followed by delayed recurrence of lesions. The indirect fluorescent antibody test done with amastigote antigen was used to monitor treatment of 122 cases of cutaneous lesions and one patient with mucocutaneous disease. Clinical improvement and healing of lesions in many, but not all, cases was accompanied by a diminution of antibody titer, and in 10% of cases, by reversion to negativity. In two cases persistence of antibody in spite of healing was shown to be due to residual viable parasites which caused recurrence or new lesions. Further treatment brought about healing and reversion to seronegativity. The data suggest that successful treatment can be indicated by serologic response and, even in cases in which reversion to seronegativity does not occur, the relative reduction in serum antibody provides a basis for predicting recurrence of leishmanial lesions.