1. Wildlife reservoirs of mosquito borne diseases: Ross River virus, a case study
Eloise Stephenson1, Cassie Jansen2, Alison Peel1, Simon Reid3 & Hamish McCallum1
1Environmental Futures Research Institute, Griffith University
2Metro North Public Health Unit, Queensland Health
3School of Public Health, University of Queensland
Eastern grey kangaroo – Photographed 8th of July 2016 in Sherwood, Brisbane

2. Outline Zoonoses Human health Management Ross River virus
Current challenges
Systematic approach in light of Ross River virus
Key conclusions

3. Zoonoses and human health
Weaver & Barrett (2004)
Zoonoses and human health
OIE (2016)

4. Zoonoses and management challenges
Human
Environmental
Animal
= disease

5. Zoonoses and management challenges
Human
Mosquito
Environmental
Animal
= disease

6. Ross River virus

7. Ross River virus Big problem in Australia - Widespread
- ↑ public health costs
- No vaccine or treatment
- Average of 4800 cases/yr
- Recent outbreak

8. > > Ross River virus Marsupials Placental Mammals Birds
2. Complex epidemiology
- > 30 sp. mosquito
- Human-mosquito-human  number of cases alone
- Non-human reservoirs
>
>
Marsupials
Placental Mammals
Birds

9. Where to begin?

10. Potential Reservoir Species Criteria Analyses (PCR, Serology)
Research Question
Methodology
Status
Phase 1: RRV Reservoir Knowledge (What do we really know?)
1. Collate Information
Literature Review
Draft in progress
Phase 2: Vector-Host Relationships (Systematic approach to understanding)
Potential Reservoir Species Criteria
2. Vector-Host Relationship
Initial phases
Analyses (PCR, Serology)
3. Sampling
Samples in discussion
Model Predicted Areas
4. Correlate Data
Not yet commenced
Phase 3: Management Strategies (in light of new findings)
5. Inform Strategies
Current Strategy Gaps
Not yet commenced

11. Total number of studies Experimental Infection
Phase 1: RRV Reservoir Knowledge (What do we really know?)
1. Collate Information
Literature Review
Draft in progress
Kay et al (1986)
Different Methods
Experimental Infection
Study type
Total number of studies
Location of studies
Date range of studies
Strengths
Limitations
Experimental Infection 7
QLD
Controlled conditions (such as viral dose)
Not indicative of natural epidemiology
Virus isolation 4
QLD, VIC
Demonstrates presence of virus
- Only a small window of opportunity to identify
- Difficult to do in random wild animal samples
Serology  35
QLD, NSW, WA, VIC, SA, NT, TAS, New Guinea, Fiji, New Zealand
Indicates previous infection
No evidence for active amplification
Blood meal analysis
QLD, WA, NSW, SA
Indication of natural epidemiology
Seroprevalence
Virus Isolation
54.2%
43.9% x3
11%
14% x2
x15
Blood meal analysis

12. Potential Reservoir Species Criteria
Phase 2: Vector-Host Relationships (Systematic approach to understanding)
2. Vector-Host Relationship
Potential Reservoir Species Criteria
Initial phases
What defines a reservoir?
Arboviruses = 3 criteria commonly used
Virus isolation
High antibody prevalence
Demonstration of viremia
Different definitions
Important  Reservoir – Lacks greater ecology

13. Potential Reservoir Species Criteria
Phase 2: Vector-Host Relationships (Systematic approach to understanding)
2. Vector-Host Relationship
Potential Reservoir Species Criteria
Initial phases
Human
Virus isolation
High antibody prevalence
Demonstration of viremia
Environmental
Animal
= disease

14. Analyses (PCR, serology)
Phase 2: Vector-Host Relationships (Systematic approach to understanding)
Analyses (PCR, serology)
3. Sampling
Samples in discussion
10-20 species
Wildlife Health Networks
Samples

15. Potential Reservoir Species Criteria Analyses (PCR, Serology)
Research Question
Methodology
Status
Phase 1: RRV Reservoir Knowledge (What do we really know?)
1. Collate Information
Literature Review
Draft in progress
Phase 2: Vector-Host Relationships (Systematic approach to understanding)
Potential Reservoir Species Criteria
2. Vector-Host Relationship
Initial phases
Analyses (PCR, Serology)
3. Sampling
Samples in discussion
Model Predicted Areas
4. Correlate Data
Not yet commenced
Phase 3: Management Strategies (in light of new findings)
5. Inform Strategies
Current Strategy Gaps
Not yet commenced

16. Key conclusions

17. Non-human vertebrate species are critical for the spread and maintenance of arboviruses
Identifying wildlife reservoirs of arboviruses cannot be done without collaborations
Better management strategies are needed which incorporate wildlife reservoir epidemiology

18. Rare -

19. References
Ashford (2001) What it takes to be a reservoir host. Belgian Journal of Zoology. 127.
Haydon et al (2002) Identifying reservoirs of infection: A conceptual and practical challenge. Emerging Infectious Diseases. 8(12):
Kay et al (1986) Experimental infection of vertebrates with Murray Valley encephalitis and Ross River viruses. Arbovirus Research in Australia
NNDS (2016) National Notifiable Diseases Surveillance System, Summary Tables. Available:
OIE (2016) One Health at a Glance. One Health. Available:
Viana et al (2014) Assembling evidence for identifying reservoirs of infection. Trends in Ecology and Evolution. 29(5): 270-9
Weaver & Barrett (2004) Transmission cycles, host range, evolution and emergence of arboviral disease. Nature Reviews Microbiology. 2(10):

20. Acknowledgements Supervisors - Funding –
Cassie Jansen: Queensland Health
Alison Peel: Griffith University
Hamish McCallum: Griffith University
Simon Reid: The University of Queensland
Funding –
Environmental Futures Research Institute, Griffith University
Clip art - Prawny
Eastern grey kangaroo photo – St Aidan’s AGS

21. Questions? @elle_stephenson Eloise Stephenson
Eastern grey kangaroo – Photographed 8th of July 2016 in Sherwood, Brisbane