PPD (Purified Protein Derivative) was injected intradermally in 236 leprosy patients (138 of multibacillary form and 98 paucibacillary), 297 healthy household leprosy contacts. The less reactive population to PPD was composed of multibacillary patients with a positivity rate of 42%, 62,2% for paucibacillary and 63,2% for contacts. Among the multibacillary patients the BI (Bacteriological index) seems to interfere with PPD reactivity. It was found a significative association between negative response to PPD and BI greater than 3+ (p<5). It was observed high positivity rate to PPD in healthy household contacts (61,0%) and paucibacillary leprosy patients (65,3%) with positive Mitsuda Skin test.
