Abstract
Psittacid Adenovirus-2 (PsAdv-2) was identified in captive orange-bellied parrots (Neophema chrysogastor) during a multifactorial cluster of mortalities at the Adelaide Zoo, South Australia, and an outbreak of Pseudomonas aeruginosa septicaemia at the Tasmanian Department of Primary Industries, Parks, Water and Environment captive breeding facility, Taroona, Tasmania. This was the first time that an adenovirus had been identified in orange-bellied parrots and is the first report of PsAdv-2 in Australia. To investigate the status of PsAdv-2 in the captive population of orange-bellied parrots, 102 healthy birds from five breeding facilities were examined for the presence of PsAdv-2 DNA in droppings and/or cloacal swabs using a nested polymerase chain reaction assay. Additionally, eight birds released to the wild for the 2016 breeding season were similarly tested when they were recaptured prior to migration to be held in captivity for the winter. PsAdv-2 was identified in all breeding facilities as well as the birds recaptured from the wild. Prevalence of shedding ranged from 29.7 to 76.5%, demonstrating that PsAdv-2 is endemic in the captive population of orange-bellied parrots and that wild parrots may have been exposed to the virus. PsAdv-2 DNA was detected in both cloacal swabs and faeces of the orange-bellied parrots, but testing both samples from the same birds suggested that testing faeces would be more sensitive than cloacal swabs. PsAdv-2 was not found in other psittacine species housed in nearby aviaries at the Adelaide Zoo. The source of the infection in the orange-bellied parrots remains undetermined. In this study, PsAdv-2 prevalence of shedding was higher in adult birds as compared to birds less than one year old. Preliminary data also suggested a correlation between adenovirus shedding prevalence within the breeding collection and chick survival.
Highlights
The orange-bellied parrot (Neophema chrysogaster) is the most critically endangered parrot in the world [1]
Detailed protocols are in place, including the isolation of breeding stocks from other captive parrots, testing and quarantine, to minimise the impact of diseases in the captive breeding program and to prevent the introduction of disease from the captive-raised orange-bellied parrots to the wild orange-bellied parrots [43]
The identification of adenovirus inclusions in birds dying from a multifactorial disease at the Adelaide Zoo, and from Pseudomonas aeruginosa septicaemia at the Taroona breeding facility prompted efforts to determine the specific adenovirus that was causing these lesions, determine how widespread infection was in the captive breeding stock, and if the wild birds had already been exposed
Summary
The orange-bellied parrot (Neophema chrysogaster) is the most critically endangered parrot in the world [1]. It is a migratory species that breeds in south-western Tasmania and historically wintered along the coast of South Australia, Victoria, and New South Wales. It was abundant before the 1920s [2], but declined to around 200 birds in the 1990s [3]. While many possible causes have been suggested, the threatening processes driving this decline are incompletely understood (reviewed in Stojanovic et al [5]). To save this species, a captive breeding program was initiated in 1984 [6]. The wild population is augmented annually with the release of captive bred birds to the breeding ground each spring [4]
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