Experimental infection of juvenile domestic and Canada geese with two different clades of H5N1 high pathogenicity avian influenza virus

Eighteen-day-old domestic geese (Anser anser f. domestica) and 3-week-old Canada geese (Branta canadensis) were experimentally infected with 106 EID50/bird of H5N1 high pathogenicity avian influenza (HPAI) virus isolates belonging to clades 1 and 2.2. Clinical signs were observed in all of the groups and included listlessness, inappetence, marked incoordination, torticollis, paralysis and lethargy. Mortality reached 100% (Canada geese) and 40–50% (domestic geese). During necropsy, congestion and hemorrhagic lesions were most often observed. Histopathological lesions were located in multiple organs and included inflammatory and hemorrhagic changes and, in later stages, occurrences of necrosis. All of the tested organ samples collected between 3 and 8 days PI were found positive in rRT-PCR, but the highest concentration of RNA was found in the brain. The observed delayed onset of mortality and prolonged duration of the disease in young domestic geese may be related to numerous host and virus factors.