Multisystemic Listeriosis in a Common Brushtail Possum (Trichosurus vulpecula) and Two Common Ringtail Possums (Pseudocheirus peregrinus)

Abstract

A single free-ranging common brushtail possum (Trichosurus vulpecula) and 2 captive sibling common ringtail possums (Pseudocheirus peregrinus) from a zoological facility in Sydney, Australia, were diagnosed with multisystemic listeriosis. The brushtail was found dead in an animal enclosure while the ringtails presented with signs of cardiovascular collapse and died shortly thereafter. All 3 animals were culture positive for Listeria monocytogenes and demonstrated focal suppurative lesions within the brainstem in addition to fulminant disease in other areas of the thorax and/or abdomen. Listeriosis in phalangeriformes species has rarely been reported, and brainstem lesions have not previously been described. It is speculated that access to the brainstem by the organism may have occurred hematogenously or via retrograde migration along cranial nerves. Sources of infection and the possibility of transmission between animals are also discussed.