:::}

Paracoccidioidomycosis produces major pathological tissue alterations characteristic of a chronic granulomatous disease. The host immune response is associated with hypergammaglobulinemia, elevated levels of immune complexes, activation of the complement system, and impaired cellular immunity. In the disseminated form, granulomas are not formed and T-cell hyporeactivity is a hallmark, while in the localized form, patients mount a granulomatous response and possess functional T lymphocytes. To establish the true prevalence of paracoccidioidomycosis (the disease as well as the infection), clinical diagnosis and serological tests help greatly in establishing an unequivocal diagnosis. The former requires the demonstration of characteristic multiple budding yeast cells in biological fluids or tissue sections; the latter requires the existence of specific antigens for reliable results. Immunological methods rely on the identification of the host's humoral responses, which are usually impaired or absent in patients with severe juvenile forms of the disease and in immunocompromised patients. Determining disease activity or assesing treatment responses by measuring antibody levels is difficult, since antibody titers may remain elevated or persist at stationary levels, even in the presence of clinical improvement.