ABSTRACT
Numerous host proteins recognize structures or molecular patterns present on foreign organisms,1 though progression of infection and clinical outcome is dependent upon environmental factors (nutritional status, previous vaccination, and exposition to environmental pathogens) and genetic background of either the pathogen or host. It is estimated that susceptibility to infectious diseases is a phenomenon that occurs in a small percentage of the exposed population. Moreover, diseases usually present different clinical patterns and exhibit mild or severe states, such as tuberculoid or lepromatous forms of leprosy; mild or hemorrhagic forms of Dengue fever; cutaneous or visceral forms of Leishmaniasis; asymptomatic or cardiomyopathic forms of Chagas disease or even pleuritic and pulmonary forms of tuberculosis.
