Current trends and future directions in koala chlamydial disease research
Grogan, LF, Ellis, W, Jones, D, Hero, J, Kerlin, DH & McCallum, H 2017, Biological Conservation, vol. 215, no. 1, pp. 179-188.
A review of nearly five decades of peer-reviewed publications about koala chlamydiosis has revealed a significant gap in the research regarding studies of the disease at the population level. Such studies will be necessary in the future to inform conservation policies and programs for declining koala populations.
The authors undertook a quantitative systematic literature review of research relating to koala chlamydiosis with the objective of identifying trends, weaknesses, gaps and directions for further research in the context of conserving populations in decline. Between 1970, when the first relevant study was published, and 2016, 117 peer-reviewed papers were published on the topic of koala chlamydiosis. The most notable finding of the review was a lack of population-level studies of disease dynamics or impacts, comprising only 14% (16 studies) of the literature. This statistic is particularly alarming given the roles of chlamydial infection and disease in koala population declines, as well as the recent socio-political emphasis on disease mitigation as a conservation strategy for koalas. The 16 studies of disease at the population level were limited both spatiotemporally and methodologically. Although the total body of literature was spatially biased towards the northern extents of the koala’s range, where the threat of disease to the species is greatest, more than half of the population-level disease studies were based on Victorian populations. As Victorian populations are presently of lower concern regarding the threat of disease than Queensland and New South Wales populations, the lack of population-level disease studies based on the latter populations reveals a poor understanding of infection dynamics where the disease is most prevalent. Furthermore, understandings of population-level disease dynamics may be outdated, with only three of these studies published in the past 20 years. The most common methodologies employed for investigating disease at the population level were observational cross-sectional and comparative studies, with few manipulative or longitudinal studies. Apart from the research gaps discussed, the literature was found to be otherwise diverse, transdisciplinary, and shaped by developments in the field.
Identifying trends and gaps in koala chlamydiosis research is essential for developing an agenda for future research and, as a consequence, conservation policies and programs for declining koala populations. This review identified a particular need for population-level disease data, which are necessary for (1) understanding the dynamics of disease in complex environments of scale, and (2) generating additional data about demography and population structure that may shed light on disease mechanisms at the population level.
As a result of their findings, the authors recommend that future studies utilise manipulative hypothesis-testing and longitudinal methodologies to explore disease dynamics at the population level. Further, such studies should be geographically diverse and incorporate sophisticated diagnostic methods that will enable researchers to better understand the diversity, mechanisms and parameters of chlamydial infections in koalas.
Summarised by Joanna Horsfall
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