Combating a novel bacterial pathogen threatening wildlife in a biodiversity hot-spot

A collaborative project undertaken by Jessica Agius in association with Taronga Conservation Society Australia and The University of Sydney, and supervised by Drs David Phalen, Karrie Rose and Hannah Bender

Background:


Christmas Island is a remote tropical landmass and prime example of an ecosystem devastated by various anthropogenic drivers. Prior to human settlement the island was a biodiversity hotspot, maintaining an array of diverse keystone endemic species; however, in the last three decades population declines and extinction events have occurred.  The contraction of critically endangered Christmas Island lizard populations has been associated with habitat destruction and fragmentation, and the introduction and expansion of invasive species.  A recently emergent, novel bacterium now threatens efforts to conserve the Lister's gecko (Lepidodactylus listeri) and blue-tailed skink (Cryptoblepharus egeriae).  The causative agent is a newly described species of Enterococcus. Affected lizards initially develop swelling around the head and eyes, eventually succumbing to systemic disease and death. Knowledge surrounding the prevalence, distribution and mechanisms of disease are limited, and the susceptibility of non-reptile species to infection is unknown.
 

Aims:

The overarching aim of this research is to protect the health of the last remaining reptiles on Christmas Island by informing Christmas Island National Park resource and endangered species management actions.  This grant supports the research undertaken by University of Sydney and Taronga Conservations Society Australia student Jessica Agius as part of her PhD candidature.  Specific objectives of Jess’s research include:
 

  • Complete genetic characterisation of the infectious agent
  • Identify the route of transmission and pathologic mechanisms of disease and death
  • Determine microbial culture requirements, and virulence traits associated with the bacterium,
  • Develop a rapid, highly sensitive and specific diagnostic test for effective conservation management,
  • Understand the ecology of this organism and its capacity to live/persist within the environment,
  • Develop a management approach for effective control and mitigation of the disease.

This research will provide new insights into the epizootiology and pathogenicity of a novel Enterococcus species fatal to endangered Christmas Island reptiles.  Research outcomes will equip Christmas Island National Parks personnel to prevent infection in captive animals, and limit the spread of infection to new species and environments through a rigorous understanding of host-pathogen-environment interactions.

Publications:

Rose, K., Agius, J., Hall, J., Thompson, P., Eden, J., Srivastava, M., Tiernan, B., Jenkins, C. & Phalen, D. (2017). Emergent multisystemic Enterococcus infection threatens endangered Christmas Island reptile populationsPLOS ONE, vol. 12, no. 7, pp. e0181240

 

Figure 1. Swelling around the eyes and mouth in an Asian house gecko with Enterococcus infection. Credit: Justin Welbergen.

Figure 1. PhD student Jessica Agius performing field work on Christmas Island. Credit: David Phalen.