During the past decade, there has been an increase in the number of patients with disseminated leishmaniasis (DL), which is characterized by a large number of acneiform and papular skin lesions, with very few or no parasites in the skin tissue. The present report describes 42 cases of DL identified between 1992 and 1998 in an area where Leishmania braziliensis transmission is endemic; 8 of the patients were prospectively diagnosed. In a contrast to localized cutaneous leishmaniasis (LCL), acquisition of DL was associated with age >19 years (P<.05), male sex (P<.05), and agricultural occupation (P<.001). Patients with DL presented with 10-300 lesions that were a mixture of acneiform, papular, nodular, and ulcerated types. Twelve (29%) of 42 patients had mucosal involvement. Patients with DL had lower levels of interferon-gamma (P<.05) and tumor necrosis factor-alpha (P<.05) production, compared with patients with LCL. DL is an emerging clinical distinct form of leishmaniasis associated with agricultural activities and host immunological response.

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The clinical spectrum of leishmaniasis and control of the infection are influenced by the parasite-host relationship. The role of cellular immune responses of the Th1 type in the protection against disease in experimental and human leishmaniasis is well established. In humans, production of IFN-γ is associated with the control of infection in children infected by Leishmania chagasi. In visceral leishmaniasis, an impairment in IFN-γ production and high IL-4 and IL-10 levels (Th2 cytokines) are observed in antigen-stimulated peripheral blood mononuclear cells (PBMC). Moreover, IL-12 restores IFN-γ production and enhances the cytotoxic response. IL-10 is the cytokine involved in down-regulation of IFN-γ production, since anti-IL-10 monoclonal antibody (mAb) restores in vitro IFN-γ production and lymphoproliferative responses, and IL-10 abrogates the effect of IL-12. In cutaneous and mucosal leishmaniasis, high levels of IFN-γ are found in L. amazonensis-stimulated PBMC. However, low or absent IFN-γ levels were observed in antigen-stimulated PBMC from 50% of subjects with less than 60 days of disease (24 ± 26 pg/ml). This response was restored by IL-12 (308 ± 342 pg/ml) and anti-IL-10 mAb (380 ± 245 pg/ml) (P<0.05). Later during the disease, high levels of IFN-γ and TNF-α are produced both in cutaneous and mucosal leishmaniasis. After treatment there is a decrease in TNF-α levels (366 ± 224 pg/ml before treatment vs 142 ± 107 pg/ml after treatment, P = 0.02). Although production of IFN-γ and TNF-α might be involved in the control of parasite multiplication in the early phases of Leishmania infection, these cytokines might also be involved in the tissue damage seen in tegumentary leishmaniasis.Correspondence