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Etiology
Aspergillus fumigatus is an opportunistic, ubiquitous soil saprophyte. It is a mycelium-forming true fungus, classified as an Ascomycete, capable of asexual reproduction. The genus Aspergillus includes a variety of related fungi which cause aspergillosis. The causal agent of avian aspergillosis is usually Aspergillus fumigatus, with occasional reports of Aspergillus flavus, Aspergillus niger, Aspergillus nidulans and Aspergillus terreus
Transmission
Aspergillosis is the most frequently occurring fungal infection in birds. All species are susceptible. Contaminated food, water, and nesting material are sources of exposure to spores. Spores often become airborne in dry windy weather spreading from one location to another.
Aspergillus can also infect the developing embryo by penetrating the egg while the embryo is developing. Infected eggs may develop a slightly greenish tint when candled. Well developed lesions may appear on infected embryos after they hatch.
Clinical signs
Acute aspergillosis usually presents fairly non-specifically, with anorexia, inappetance, depression, dyspnea, polydipsia, polyuria, cyanosis, or sudden death may occur. White, mucoid exudation, marked congestion of the lungs and air sacs, and pneumonic nodules may be present.
In the chronic form, dyspnea, voice change, lethargy, depression, emaciation, polydipsia, and polyuria may occur. Extensive involvement of the respiratory tract can be present before clinical signs are apparent. Hepatic involvement may cause biliverdinuria and hepatomegaly; CNS involvement ataxia, torticollis and seizures or hind limb paresis/paralysis Diagnosis
Diagnosis of avian Aspergillosis can be difficult, at best, other than by autopsy. Tentative diagnosis can be made with clinical signs as well as the absence of bacterial infection in moist exudates. A blood test showing an elevation in white blood cell count, mild anemia and an elevation in the monocytes also supports this diagnosis.
X-rays changes seen in advanced disease include a parabronchial pattern, loss of definition of airsacs, asymmetry due to consolidation or hyperinflation, or focal densities. Hepatomegaly or renomegaly may be visible with involvement of these systems. Treatment
The best treatment involves surgical debridement of the lesions, followed by topical therapy in conjunction with aggressive systemic antifungals. Amphotericin B, 5-fluorocytosine, ketoconazole, miconazole, enilconazole, itraconazole, rifampicin and dimethyldithiocarbamate have all been reported in treatment of aspergillosis Prevention
Environmental hygiene and ventilation should be maximised and stress reduced
Tags: Article Poultry Avian Aspergillosis
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