EDS ‘76 is caused by a double-stranded DNA virus, duck adenovirus 1 (also known as EDSV), which belongs to the genus Atadenovirus. The virus commonly infects both wild and domestic ducks and geese, but evidence of infection has also been found in coots, grebes, herring gulls, owls, storks, swans, and quail. The adenovirus group antigen cannot be demonstrated by conventional means, and EDSV differs from other avian adenoviruses by strongly agglutinating avian RBCs, a fact that allows use of a hemagglutination-inhibition test for detection of antibodies to the virus. The virus grows to high titers in embryonated duck and goose eggs and in cell cultures of duck or goose origin. It replicates well in chick-embryo liver cells, less well in chick kidney cells, and comparatively poorly in chick-embryo fibroblasts. It does not grow in embryonated chicken eggs or in mammalian cells. The virus is resistant to pH range 3–10 and to heating for 3 hr at 56°C (132.8°F). Infectivity is lost after treatment with 0.5% formaldehyde or 0.5% glutaraldehyde.