Study of antibodies in paracoccidioidomycosis: follow-up of patients during and after treatment.

The relevance of the humoral response in the prognosis of paracoccidioidomycosis was assessed by measuring the serological responses of individual patients to Paracoccidioides brasiliensis by double immunodiffusion (DID). Sixty-six patients with paracoccidiodomycosis were studied. Sera from 31 individuals were tested before and during treatment with sulfonamide (Group I). Sera from a further 35 individuals were tested after completion of a 2-year course of treatment (Group II). In Group I, clinical improvement was associated with a decrease in antibody titer in all patients. The only patient in this group who had a clinical relapse during specific treatment presented with a 4-fold increase in antibody titer immediately before relapse. In Group II, nine patients remained antibody positive at follow-up (61.9 +/- 40.0 months), despite their good physical health, indicating that the detection of antibodies to P. brasiliensis by the DID test does not necessarily indicate active disease. These data suggest that changes in antibody titers to P. brasiliensis detected by DID may be useful indicators of the extent of active disease. Measurement of antibody titers may be valuable for determining the prognosis of the infection and for deciding on a suitable treatment protocol.