Submitted to: Proceedings of North Central Avian Disease Conference
Publication Type: Proceedings
Publication Acceptance Date: July 19, 1996
Publication Date: N/A
Technical Abstract: Aspergillus fumigatus is an ubiquitous fungal saprophyte and opportunistic respiratory tract pathogen of animals. Avian species are especially susceptible to pulmonary aspergillosis which produces granulomatous pleuropneumonia and air sacculitis. Aspergillosis is an economically significant disease of poultry. Mortality, poor feed conversion, lower market weight, and processing plant condemnations contribute to losses. In humans, aspergillosis can occur either as an allergic disease mediated by exaggerated host inflammatory responses or as chronic infections due to inadequate immune defenses. The role, if any, of hypersensitivity reactions in the development of avian aspergillosis is obscure. This study addresses the potential of intact killed conidia to initiate pathological responses when introduced into the pulmonary tract of the turkey. Lesions induced are compared to those produced by acute infection. Killed A. fumigatus conidia elicited an intense inflammatory reaction in lung tissue of turkeys within 6 hours of intra-air sac inoculation. The killed conidia were cleared, and the inflammation subsided by 72 hr PI. In contrast, turkeys inoculated with viable conidia developed progressively severe pneumonia with persistence of intralesional fungal elements through the three days of the study. The observation that nonviable A. fumigatus can cause striking, although rapidly transient, pulmonary lesions following a single exposure indicates that the host response may contribute in a major way to the natural disease process. In addition, the progressive nature of the inflammatory response and necrosis induced by the growth of A. fumigatus in the turkey lung demonstrates the inherent virulence of this pathogen.