Pathogen Type: fungi


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Aspergillus spp are fungi that are widely distributed throughout the environment in the air, dust, soil, decaying vegetation, and organic debris. Species most isolated from horses include A. flavus and A. fumigatus.

A. flavus is found often in hot, humid climates. The presence of fungi does not necessarily imply the presence of toxins. The fungi species can produce aflatoxins on commodities in the field under stress conditions or in storage when high moisture and warm temperature propitiate their growth.

A. fumigatus does not normally infect normal healthy horses, however, they are very opportunistic, so horses are exposed to large quantities (such as when exposed to very dusty barns or fed dusty or moldy hay) or has a concurrent illness or immunodeficient are most at risk of infection. A. fumigatus is normally inhaled by susceptible horses, but can sometimes be ingested or even transmitted via direct contact occasionally. A. fumigatus infection causes aspergillosis, which manifests as guttural pouch mycosis, pulmonary disease, keratomycosis

Equine keratomycosis: A. fumigatus is the most common cause of infection in horses, with studies showing that the organism was isolated from 33 to 77% of eyes of horses with keratomycosis.