ABSTRACT
This chapter explores the sources of infection, portal of entry, dissemination routes, and the host-parasite relationship. Paracoccidioidin surveys seem to clearly point out the existence of a paracoccidioidomycosis infection, without disease, similar to that seen in other systemic mycoses. The studies of experimental paracoccidioidomycosis in mice carried out by Mackinnon et al. decisively supported the inhalatory route of infection. Paracoccidioidomycosis may become disseminated by proximity, following the canalicular routes, the lymphatic flow or the blood stream. The progress of paracoccidioidomycosis depends both on the virulence of the infecting agent and on the defensive capacity of the host. Clinical evidence as well as experimental studies have shown that cell-mediated immunity is the main mechanism of host defense. The levels of P. brasiliensis antigens in the peripheral blood of patients with paracoccidioidomycosis are directly related to the severity of the disease.
