Chapter 51 Viral Chorioretinitis of Kangaroos
A widespread outbreak of viral chorioretinitis in wild kangaroos received considerable media attention in Australia and worldwide in the 1990s. Many blind kangaroos were first observed along the Darling River in western New South Wales between April and July 1994. Between March and June 1995, the disease reappeared, with larger numbers of affected animals, and extended into northwestern Victoria and southeastern South Australia. The condition reappeared again the following year and, between December 1995 and April 1996, kangaroos in southern Western Australia were also affected. There had been anecdotal reports of similar outbreaks of blindness in kangaroos as early as 1905, and in the 1940s through the 1960s, but these were never investigated in any detail, so the cause remained uncertain. However, an outbreak of kangaroo blindness in northwestern Victoria in 1975 with similar histopathologic findings was retrospectively confirmed as viral chorioretinitis by polymerase chain reaction (PCR) testing of archived material. Durham and colleagues2 have described the condition as seen in South Australia, and field observations and epidemiology were described by Curran and associates.1 Comprehensive laboratory investigations (e.g., virus isolation, serology, histopathology, electron microscopy, molecular testing) of field cases indicating a viral cause were described by Hooper and coworkers.3 A viral cause was confirmed when the disease was replicated by experimental inoculation of captive kangaroos, as described by Reddacliff and colleagues.4
