1. Stephen L. Doggett Senior Hospital Scientist
Department of Medical Entomology, ICPMR, Westmead Hospital, Westmead NSW 2145

2. Overview Factors driving arbovirus activity Methods of surveillance
NSW Arbovirus Program
Enhanced surveillance!
Information dissemination
How to use surveillance data
Case study: MVEV in 2008
A little challenge…

3. Factors Driving Arbovirus Activity
Temperature drives mosquito activity
Water drives mosquito abundance
Water – rain, tides, humidity
Distribution of vectors & reservoir hosts
Host/herd immunity
Reservoirs & humans
Low immunity – pot. larger outbreaks
Virus & virus strain
Various human behaviours

4. Arbovirus Surveillance in NSW
Predictive
Weather patterns
Vector populations
Virus infected mosquitoes
(Computer modeling)
Transmission
Sentinel animals (MVEV & KUNV)
Humans
Program must be tailored to the virus, the virus ecology and the human population

5. NSW Virogeographic Regions
RRV, MVEV, KUNV
Culex annulirostris
RRV, BFV
Aedes vigilax

6. NSW Surveillance Locations

7. Weather Patterns Rainfall Level of mosquito abundance
Climatic indicators (El Nino/SO)
Long term mosquito/arbovirus activity
MVEV hypotheses: Forbes, Nichols

8. Weather - MVE models Forbes’ hypothesis Catchment Basin Oct-Dec 2014
Jan-Mar 2015
Oct-Dec 2015
Jan-Mar 2016
Darling River
0.80
0.65
0.48
Lachlan/ Murrumbidgee/ Murray Rivers
0.97
1.05
0.29
Northern Rivers
0.94
0.67
0.33
North Lake Eyre system
1.07
0.11

9. Nicholls’ Hypothesis
Southern Oscillation

10. Weather Patterns Rainfall Level of mosquito abundance
Climatic indicators (El Nino/SO)
Long term mosquito/arbovirus activity
MVEV hypotheses: Forbes, Nichols, Bennett
Tidal
Level of saltmarsh mosquito abundance

11. Tide & Mosq. Populations
Tide height (m)
Mosquito Numbers

12. Tide & Mosq. Populations

13. Weather Patterns Rainfall Level of mosquito abundance
Climatic indicators (El Nino/SO)
Long term mosquito/arbovirus activity
MVEV hypotheses: Forbes, Nichols, Bennett
Tidal
Level of saltmarsh mosquito abundance
Advantage: Cheap!
Disadvantage: Least sensitive method

14. Vector Populations Determine species composition
Examine seasonal abundance
Arbovirus detection
Quarantine
Long term
Mosquito population monitoring
Arbovirus monitoring
Changes in vector distribution
Control Programs

15. EVS Trap (Encephalitis Vector Surveillance Trap) Adult monitoring

16. Vector Population Monitoring

18. Virus Isolation from Vectors
Provide information on ‘normal’ activity
(long term)
Early indication of virus activity/type
identify potential outbreaks
Identify new vectors
Monitor new virus incursions
Traditionally via ‘cell culture’

21. Virus Identification Times

22. Honey-Baited Cards

23. Honey-Baited Cards FTA cards coated with honey
Placed into mosquito trap
Mosquitoes spit virus
Cards tested via molecular tests
Advantages

24. Virus Identification Times

25. Honey-Baited Cards FTA cards coated with honey
Placed into mosquito trap
Mosquitoes spit virus
Cards tested via molecular tests
Advantages
Rapid: 1-2 days
Sensitivity: > cell culture, > animals
Labour savings!!!

26. But can we do even better?

27. Sugar Bait Stations
Lark Coffey, UC Davis

28. Advantages/Disadvantages
Mosquito Population Monitoring
Highly significant relationship between mosquito populations & human disease
Field equipment cheap & portable
Traps can be placed in viral ‘hot spots’
Laboratory labour intensive
Virus Isolation
Good early indicator of epidemic activity
Need to process many mosquitoes (1 virus in 2-4,000 mosquitoes)

29. Human Cases Advantages Most sensitive but…
Provide epidemiological information
Provide information on ‘risk’, e.g.
geographic exposure, time of exposure
determine when health warnings are needed
Modify existing surveillance programs
Disadvantage
Too late for health interventions

30. Information Dissemination
NSW Arbovirus Surveillance Web Site
Weekly reports
Annual reports
Special reports

31. So how can the data be used?
Base mosquito warnings on the data
The timing & degree
Use the data in media campaigns
It’s mosquito season:
Take Precautions!
Mosquito numbers 8x normal
Increased Disease Risk!
Virus detected in mosquitoes
Disease Outbreak Feared!

32. Case Study MVEV 2008

33. MVEV 2008: Background Forbes: not fulfilled Nichols: not fulfilled
Summer rainfall: >average
Low irrigation allocation
Mosquito numbers: low
MVEV activity unlikely

34. MVEV Activity 2008 26/Feb/08 5/Feb/08 18/Feb/08 3/Mar/08 24/Mar/08

35. Low Pressure Cell Mid-Jan 2008 Dr Andrew Read, DPI, Menangle
Follow the Low over central QLD. Passed through western NSW into Vic and into the Tasman
Dr Andrew Read, DPI, Menangle

36. Health Actions Media releases/Fact Sheets/Radio/TV EDs, GPs contacted
Telephone Hotline ( )
Weekly teleconferences
Extended chicken/mosquito season
Established further flocks & traps
Opportunistic testing
Dept. Agriculture opportunistic testing

38. Surveillance Requires
Appropriate number of sites
Intelligently located
Multitude of methods
Continuous
Timely sample analysis & response
Review locations/techniques
Must consider vector!!!

39. Aedes albopictus Asian Tiger Mosquito (ATM)

41. Honey-Baited Cards FTA cards coated with honey
Placed into mosquito trap
Mosquitoes spit virus
Cards tested via molecular tests
Advantages
Rapid: 1-2 days

42. FTA vs CC Viral Assay BFV RRV EHV KOKV STRV Total FTA 12 68 2 82 CC 682 CC 6 17 3 1 28
No. traps = 903