The public health aspect of paromomycin-urea ointment. The true benefit of the paromomycin (aminocidine) ointment in ZCL patients (caused by L. major) in Isfahan, Iran. About 30–40% self heal within 5–6 months from onset of disease, With an efficacy of the ointment about 35–40%, 75–80 would cure within this period leaving 20–25% of refractory patients who would need other treatment. This figure indicates the importance of a placebo (control) arm in all CL studies. In addition, the duration of lesion prior to enrolment into any trial is critical, since with time, more and more cases self heal.