A Retrospective Study of Admission Trends of Koalas to a Rehabilitation Facility Over 30 Years

Abstract

To identify threats to the survival of koalas (Phascolarctos cinereus) in coastal New South Wales, Australia, we compared 3,781 admission records of koalas, admitted between 1 January 1975 and 31 December 2004 to a koala rehabilitation facility on the midnorthern coast of New South Wales, against local wild population demographics, with the use of multinomial logistic regression and chi-square analyses. Trauma, the most frequent reason for admission, affected young and male animals more frequently than other groups. Seasonal differences in the probability of males presenting as trauma cases suggest behavioral factors as an important risk factor for this group. An increasing probability of koalas presenting as a result of motor vehicle accident since 1985 strongly supports the enhanced action of local authorities to pursue traffic-calming strategies if urban koala populations are to be maintained in this area. Koalas with clinical signs of chlamydiosis made up the second most frequent admission group, and these animals were more likely to be aged. This study highlights the potential usefulness of wildlife rehabilitation centers in detailing threats to local wildlife populations, provided record keeping is efficient and focused, and the role of such studies in providing evidence for focusing threat-mitigation efforts. Continual community engagement by koala researchers is important to ensure that maximum benefit is obtained from activities of special interest groups.

Identification of MHCII variants associated with chlamydial disease in the koala (Phascolarctos cinereus)

“…While young koalas are admitted for conditions predominantly associated with dispersal, aged koalas are much more commonly admitted with chlamydial disease (Griffith et al, 2013) and this was evident in animals in this study. While DBB*02 is not likely to be a susceptibility variant due to its high prevalence in the population, studies in other species have identified a single susceptibility allele (variant) that is masked by other alleles in heterozygotes (Oliver & Piertney, 2012; Worley et al, 2010) and this might permit the persistence of a detrimental allele.…”

“…Greater consistency in detecting and speciating chlamydial infection, such as with species-specific real-time PCR (Govendir et al, 2012), and more consistent clinical classification of animals, would be desirable and possible with a prospective study. Chlamydia is an extremely challenging disease for this type of study, due to its chronicity, the cryptic nature of some of its pathological changes, and its complex pathogenesis; and the cross-sectional sampling of hospitalised koalas, which are biased for age and disease (Griffith et al, 2013), rather than longitudinal sampling of a free-ranging population, limits some conclusions. Incorporation of MHCII genetics in a longitudinal epidemiological study of a free-ranging population would be ideal; to remove biases, provide a more thorough history of disease progression, and permit more detailed survival studies.…”

“…The natural lifespan of female and male koalas is over 15 and 12 years of age, respectively (Martin & Handasyde, 1999). As young koalas are more likely to present to wildlife rehabilitators as a result of misadventure and trauma during dispersal, while older koalas more commonly present for diseases such as chlamydiosis (Griffith et al, 2013), koalas were divided into four age classes in order to assess if age was a confounding factor for antibody titres: young adult, AY, two to five years old ( n = 15); mature adult, AM, five to ten years old ( n = 33); aged adult, AA, over ten years old ( n = 25); and age unknown AU ( n = 21) based on an aging system utilising tooth wear class (Martin, 1981). …”

“…Chlamydiosis, caused predominantly by Chlamydia pecorum and C. pneumoniae , is the most common infectious disease in koalas, causing proliferative conjunctivitis and/or chronic, fibrotic disease of the urogenital tract, which can lead to infertility and death (Griffith et al, 2013; Obendorf, 1983). Heat shock proteins (hsp) are highly conserved polypeptides produced under stress conditions to preserve cellular activity, and are upregulated by Chlamydiae in their persistent intermediate forms, which are induced by IFN γ in sub-lethal Th1 immune responses (Beatty, Byrne & Morrison, 1994).…”

MHC class II diversity of koala (Phascolarctos cinereus) populations across their range

“…The survival of the koala (Phascolarctos cinereus), an iconic Australian folivorous marsupial, is threatened by habitat loss, population fragmentation, motor-vehicle strike, predation by dogs and disease (Jackson et al, 1999;Melzer et al, 2000;McAlpine et al, 2006;Griffith et al, 2013). Koalas are currently distributed in the eastern states of Australia with additional isolated populations in South Australia (Figure 1).…”