Often they are only a serious problem in people who are immunocompromised in some way. Animal hosts in rehabilitation are generally wild birds such as raptors or waterfowl. While under stress in a captive facility, rehab animals are more likely to develop the fungal disease. They in turn shed the spores of the fungus and the workers may inhale them. In birds, respiratory signs.
Most healthy people have no trouble resisting infection.
However, this is not true for anyone who has been debilitated by illness, other diseases, or has been on long term antibiotic, antimetabolite, or corticosteroid therapy. At least 12 air exchanges per hour are recommended in any room where susceptible birds are housed. Waterfowl are not to be housed on wood shavings because the fungus will thrive in them when wet. Moldy grains and food stuffs are not fed or stored. Necropsies are performed with masks as are treatments on suspect patients.