Network analysis of wildlife translocations in New Zealand

Prevalence of Salmonella spp. in translocated wild reptiles and effect of duration of quarantine on their body condition

AIMS

To assess the prevalence of carriage of Salmonella spp. in wild reptiles translocated from multiple locations to a single island, and determine changes in their body condition (BC) during quarantine.

METHODS

Between 2007 and 2009, six endemic reptile species (Oligosoma aeneum, O. moco, O. ornatum, O. smithi, Dactylocnemis pacificus, and Woodworthia maculata) were caught from several locations in the northern North Island of New Zealand. Reptiles were held in quarantine for 14-41 days while being tested for carriage of Salmonella spp. Morphometric data were collected, and scaled body mass index for each species was calculated to determine changes in BC during the quarantine.

RESULTS

Of 221 individuals tested 12 (5%) were positive for Salmonella spp. All 12 were shore skinks (O. smithi; n = 30), with a test prevalence of 0.4 (95% CI = 0.25-0.58). Eleven were carrying Salmonella enterica Warragul and one S. enterica Mississipi. There was no difference in BC at the start of quarantine of shore skinks between those that tested negative and those that tested positive for Salmonella spp. (p = 0.184). Reptiles that were quarantined for 15-20 days (three species) lost 3-5% of BC (mean proportional change 0.03-0.05), while those quarantined for >30 days increased BC by 3-13% (mean proportional change 0.03-0.13). All animals except the one individual positive for S. Mississippi were translocated to the recipient island, while the latter was returned to the source site.

CONCLUSIONS AND CLINICAL RELEVANCE

The prevalence of Salmonella spp. carriage in the translocated reptiles was low overall and consistent with other records of Salmonella spp. in wild New Zealand reptiles. However, the prevalence of 0.4 in shore skinks is the highest recorded in this species. In addition to time required for health-screening, we recommend that duration of quarantine should include time to allow animals to recover from captive stress and to provide an opportunity to increase their BC before release.

Wildlife diseases in New Zealand: recent findings and future challenges

Our knowledge of diseases in New Zealand wildlife has expanded rapidly in the last two decades. Much of this is due to a greater awareness of disease as a cause of mortality in some of our highly threatened species or as a limiting factor to the successful captive rearing of intensely managed species such as hihi (Notiomystis cincta), kiwi (Apteryx spp.) and kakapo (Strigops habroptilus). An important factor contributing to the increase of our knowledge has been the development of new diagnostic techniques in the fields of molecular biology and immunohistochemistry, particularly for the diagnosis and epidemiology of viral and protozoan diseases. Although New Zealand remains free of serious exotic viruses there has been much work on understanding the taxonomy and epidemiology of local strains of avipox virus and circoviruses. Bacterial diseases such as salmonellosis, erysipelas and tuberculosis have also been closely investigated in wildlife and opportunist mycotic infections such as aspergillosis remain a major problem in many species. Nutritional diseases such as hyperplastic goitre due to iodine deficiency and metabolic bone disease due to Ca:P imbalance have made significant impacts on some captive reared birds, while lead poisoning is a problem in some localities. The increasing use of wildlife translocations to avoid the extinction of threatened species has highlighted the need for improved methods to assess the disease risks inherent in these operations and other intensive conservation management strategies such as creching young animals. We have also become more aware of the likelihood of inbreeding suppression as populations of many species decrease or pass through a genetic bottleneck. Climate change and habitat loss, however, remain the greatest threats to biodiversity and wildlife health worldwide. Temperature changes will affect our wildlife habitats, alter the distribution of disease vectors and wildlife predators, or directly harm threatened species in vulnerable localities.