PATHOLOGICAL-STUDIES OF WOBBLY POSSUM DISEASE IN NEW-ZEALAND BRUSHTAIL POSSUMS (TRICHOSURUS-VULPECULA)

Following an outbreak of wobbly possum disease in a colony of brush ta il possums (Trichosurus vulpecula), the disease was established experi mentally in captive possums by inoculating the animals intraperitoneal ly with tissue homogenates. Crude tissue homogenates of liver remained infectious after freezing at -75 degrees C or filtration through a 0. 22 mu m filter, The disease was characterised by docility, incoordinat ion, loss of balance and wasting. Fifteen of 16 infected animals had t o be euthanased owing to the severity of the clinical signs. Cachexia was the only change observed postmortem, Histology revealed widespread perivascular infiltrations with plasma cells and lymphocytes which we re severe in the liver and kidney and moderate to mild in a variety of other tissues, including skeletal and cardiac muscle. Changes in the brain consisted of a mild to moderate mononuclear perivascular cuffing , Most of the animals had small to large numbers of circulating nuclea ted red blood cells and eosinopenia when they were euthanased. There w as a consistent decrease in serum albumin concentration and an increas e in serum globulins, which resulted in a decreased albumin:globulin r atio, Virus-like particles were observed in preparations of liver from two animals; they appeared to be spherical or icosahedral and were 45 nm in diameter.