Amdoparvovirus-associated disease in red pandas (Ailurus fulgens).

The roster of amdoparvoviruses (APVs) in small carnivores is growing rapidly, but in most cases, the consequences of infection are poorly understood. Red panda amdoparvovirus (RPAV) is highly prevalent in zoo-housed red pandas and has been detected in both healthy and sick animals. Clarifying the clinical impact of RPAV in this endangered species is critical, and zoological collections offer a unique opportunity to examine viral disease association in carefully managed populations. We evaluated the potential impact of RPAV in captive red pandas with a combination of prospective and retrospective analyses. First, we collected feces from 2 healthy animals from one collection over a 6-year period and detected virus in 72/75 total samples, suggesting that RPAV can be a long-term subclinical infection. We next investigated the infections using a retrospective study of infection status and tissue distribution in a cohort of necropsied animals. We performed polymerase chain reaction and in situ hybridization on 43 necropsy cases from 4 zoo collections (3 from the United States, 1 from Europe, 1997-2022). RPAV was present in these populations for at least 2 decades before its discovery and is detectable in common and significant lesions of zoo-housed red pandas, including myocarditis (3/3 cases), nephritis (9/10), and interstitial pneumonia (2/4). RPAV is also detectable in sporadic lesions, including multisystemic pyogranulomatous inflammation, oral/pharyngeal mucosal inflammation, and dermatitis. The colocalization of virus with lesions supports a role in causation, suggesting that despite the apparently persistent and subclinical carriage of most infections, RPAV may have a significant impact in zoo collections.