DISEASE RISK ANALYSIS EXAMPLES
The following two studies highlight the application of DRA methodology to the evaluation of disease scenarios where a logical and transparent framework is required to ensure future conservation efforts are appropriately directed.
3.1 Translocation of eastern barred bandicoots (EBB) (Perameles gunnii) to Phillip Is. and French Is., Vic., Australia
3.1.1 Context
The DRA was commissioned by Zoos Victoria and facilitated by the Conservation Breeding Specialist Group (CBSG) with input and collaboration of community representatives and a group of experts representing wildlife health, diagnostic, zoo management, biology and public health disciplines (Jakob-Hoff et al. 2016). The DRA was based on the IUCN guidelines (Jakob-Hoff et al. 2014a) and was completed in three stages:
• Stage 1: Review of literature on EBB biology, zoo husbandry and disease, compiled into a briefing document and circulated to experts and stakeholders.
• Stage 2: Two-day workshop to work through the DRA process, building on the information gathered in the briefing papers.
• Stage 3: Correct, update and refine the briefing papers and assemble a draft report, reviewed by workshop participants to produce a final report.
A synopsis of the DRA process for EBB translocation and the risk assessment for the hazard Toxoplasma gondii is reported below (Tables 3.2 and 3.3).
3.1.2 Review of case example
This example presents a common scenario in endangered species recovery programs in Australia, where there is a need to consider assisted colonisation to predator-free offshore islands. Performing a DRA is essential in these situations because the translocation crosses a geographical (body of water) and often also an ecological boundary (Masters and Sainsbury 2011).
This DRA used the Jakob-Hoff et al. (2014a) method and identified 26 hazards, of which three infectious hazards were assessed as being of significant concern.
As a result, a complete DRA was only conducted on these three hazards, saving considerable time. This highlights the flexibility of this DRA method, which can be modified to accommodate time, logistical and financial constraints.This method of hazard prioritisation reduces the time required to conduct a DRA and given the three hazards were well studied and documented the process was transparent. A feature of this DRA example is the formal 2-day workshop held to solicit expert opinion. The workshop enabled stakeholders to clarify their concerns as clear objectives to help drive hazard identification and assess management decisions, pool knowledge, further identify possible hazards, consider options for risk management and identify knowledge gaps (Jakob-Hoff et al. 2016). It highlighted the importance and value of risk communication at each stage of the DRA. It must, however, be acknowledged, that despite the process used in this DRA potentially being more robust and thorough, it is expensive and time-consuming, and alternative methods or an abbreviated version could yield similar results.
3.2 Disease risk analysis examples for population decline
A novel wildlife disease risk assessment methodology was reported by Pacioni et al. (2015). This study assessed the potential role of diseases in relation to the 90% population decline between 1999 and 2006 of the brush-tailed bettong (Bettongia penicillata) in WA. Published models used for assessing disease risk in wildlife translocations were used to develop a systematic framework to assess disease risk (Armstrong et al. 2003; Miller 2007). This included: generation of a comprehensive list of relevant pathogens; identification of the spatial, temporal and demographic characteristics of the decline; assessment of the general health (and health changes when possible) of the remaining populations during the decline; and assessment of hazards and identification of priorities for investigation. All hazards identified were ranked, based on available information, to prioritise investigations into potential diseases of significance.
This reduced the risk of focusing on certain hazards that may divert attention from the true causes of decline. This approach encouraged multidisciplinary collaboration, to help overcome the likelihood that one individual’s experience or expertise would bias the risk assessment. Importantly, it also helped identify knowledge gaps and facilitated allocation of resources and research efforts into these areas.Reiss et al. (2015) presented a comprehensive study of health and disease in small mammals undergoing broadscale population declines in northern Australia. A total of 281 individuals were examined and sampled under anaesthesia across five sites in the NT. Hazard identification and prioritisation followed similar methods to those of Jakob-Hoff et al. (2014a) and Pacioni et al. (2015). Refinement was undertaken by initially excluding hazards that were unsuitable for assessment (e.g. if no diagnostic test was available) and including hazards known or thought likely to cause disease. Hazards were shortlisted for further assessment by veterinarians with expertise in wildlife disease and ranked. Nine prioritised pathogen groups were then investigated by diagnostic testing and the results analysed for associations with various parameters (e.g. location, species, body condition). Molecular pathogen discovery studies were also undertaken on the northern brown bandicoot (Isoodon macrourus) to look for unrecognised pathogens. Overall, several pathogens capable of affecting population health were identified, but there was no compelling evidence of a single pathogen or a risk factor responsible for small mammal declines in the Top End of the NT (Reiss et al. 2015).
4.