SURVEY OF ANTIBODY REACTIVITY TO ASPERGILLUS IN THE COMMON LOON (GAVIA IMMER).

The common loon (Gavia immer) is considered a sentinel of ecosystem health, and declines in this species have been linked to several different drivers. Loons are widely recognized as being very sensitive to fungal respiratory disease, and this has proven a major barrier to successful clinical care and rehabilitation. The goal of the present study was to assess the presence of antibody reactivity to Aspergillus with secondary testing including Aspergillus antigen and gliotoxin detection as well as plasma protein electrophoresis and complete blood count as sample volume permitted. Conducted over two years in collaboration with multiple centers in Maine, New Hampshire, and Florida, samples were collected in the Northeast from healthy wild adult and juvenile birds (n = 72) as well as clinically abnormal birds presented for rehabilitation (n = 29). In addition, a cohort of rehabilitation samples was obtained from clinically abnormal overwintering birds (n = 6). Necropsy results were available for those found moribund or euthanized (n = 29). Of these birds, eight were confirmed to have aspergillosis where the remainder were diagnosed with other complications. Only three of eight displayed antibody reactivity to Aspergillus using a recombinant antigen-based ELISA and four tested positive for the presence of gliotoxin. An abnormal electrophoretogram was present in samples from all eight birds. The presence of antibody reactivity was not observed in clinically normal loons and only in one of the necropsied loons without aspergillosis. Overall, aspergillosis appears uncommon in healthy, free-ranging birds but likely can be an opportunistic infection after a stress inducing event. Serological testing and protein electrophoresis may provide an opportunity to monitor the health of this species and may improve the ability to manage this species in captivity.