Overview of NSW Arbovirus
Surveillance Program
Kishen Lachireddy
Senior Policy Analyst
Health Protection NSW
December 2015
Brief History
 1974 MVE outbreak
 Program started in 1979 with sentinel chicken surveillance.
 RRV outbreak in 1984 - Riverina
 Mosquito monitoring commenced in 1984/85 – Mosquito
population counts.
 Arbovirus isolations from mosquitoes started in 1988/89
season.
Arboviral Surveillance Program
Two parts to the Program:
1. Sentinel Chicken Surveillance:
The aim – to provide early warning on presence of Murray Valley
Encephalitis (MVE) and Kunjin. Reduce potential for human
disease.
2. Mosquito Monitoring:
Detect underlying causes for seasonal fluctuations in arbovirus
activity and abundance of mosquito vector species. Potential to
effect human health.
Overview of season
 Usually duration of the surveillance season is from November
to end of April (mid-spring to mid-autumn).
 Sentinel chicken flocks are bled weekly and tested for specific
viruses (MVE and Kunjin).
 Mosquitoes are collected weekly for species identification and
quantification, and processed for isolation of viruses.
 End of season – total mosquito numbers low and two
consecutive weeks of negative results for arboviral isolation. In
addition, rainfall and temperature is taken into consideration.
Sentinel Chicken Surveillance
 Sentinel flocks are located in inland areas (Southwestern
NSW) stretching from Deniliquin to Moree.
 15 birds per flock.
 Flocks are bled prior to deployment to the test sites and then
at weekly intervals.
 Tested for Kunjin and Murray Valley Encephalitis using ELISA
(Enzyme Linked Immunobsorbent Assay).
 Current season - 10 sites across the state.
Mosquito Monitoring
Mosquito Monitoring:
Trapping locations around the NSW – Major centres along the
coast, Sydney suburbs, and inland NSW towns along principal
river systems.
Current season – there are 20 different locations across NSW.
Mosquito Monitoring
Mosquito Collection and Identification
 Mosquitoes are collected overnight in dry-ice baited mosquito
traps.
 Live mosquitoes are sent to the Pathology West, Institute for
Clinical Pathology and Medical Research, Westmead for
identification and processing for arbovirus isolation.
 The mosquitoes are identified according to keys and
illustrations.
Mosquito Monitoring
Arbovirus Isolation Methodology
 Mosquitoes are sorted into pools of 25.
 Mosquitoes are ground up.
 Supernatants from these pools are inoculated into cell
cultures.
 After a number of passages on different cell lines (screened
for cytopathic effects) - plates are fixed and screened for
different viruses using monoclonal antibodies.
Participants
 Health Protection NSW
 Public Health Units
 Local Councils
 Pathology West, ICPMR, Westmead
Health Protection NSW
 Provides funding for the surveillance program.
 Coordinates running of the program along with pathology west
and training needs for the participants.
Public Health Units
PHU’s:
 Liaise with councils on any health advisories as required.
 Some PHU’s coordinate invoices from contractors and submit
to NSW Health.
 Some PHU’s undertake mosquito trapping and maintain
chicken flocks.
 Collect samples and dispatch to Pathology West, Westmead.
Local Councils
Local Councils:
 Undertake mosquito trapping and maintain chicken flocks.
 Collect samples and dispatch to Pathology West, Westmead.
Pathology West, Institute for Clinical
Pathology and Medical Research
 Provides advice to the Health Protection NSW on length of
season, extension, public health messaging and mosquito
control methods.
 Provides support to the sites in terms of supply of collection
kits, sample collection and any queries on day to day running
of the program.
 Provides testing services for different arboviruses and
prepares summary reports.
 Preparation of weekly reports during the active season and
annual report.
Arbovirus Surveillance and Mosquito Monitoring Program
Season length and extension,
Advice during outbreaks and
Training
Health Protection NSW
Environmental Health Branch
Functions:
• Provides funding for mosquito monitoring and
sentinel chicken surveillance.
• Informs PHU’s and participants the length of
season, start and finish dates for both programs.
• Coordinates training for participants of the program.
Public Health Units
Functions:
• Liaise with Councils on mosquito control or
advisories as required.
• Provide advice to health professionals.
• Collects and submits invoices to MoH, Health
Protection NSW for surveillance activities from
respective councils in their area for timely
Some PHUs:
payment.
• Maintain chicken flocks and set mosquito
traps as required.
• Collect samples and dispatch them to ICPMR
for testing.
Advisories to participants on
program and payments
Season length
and extension
Councils/
Independent Contractors
Functions:
• Maintain chicken flocks and set
mosquito traps as required.
• Collect samples and dispatch them to
ICPMR for testing.
Season length and extension,
Testing, Technical issues and
Summary reports
Institute for Clinical Pathology and
Medical Research (ICPMR)
Functions:
• Informs Health Protection NSW the length of season,
start and finish dates for mosquito monitoring and
sentinel chicken surveillance a month before season
starts.
• Provides participants with the sample collection kits and
necessary support.
• Provides advice to Health Protection NSW on extension
of the surveillance season.
• Participate in expert panel meetings and provide advice
during outbreaks.
• Tests for arboviruses and prepares summary reports
• Provides copy of the results to Health Protection NSW
on a regular basis.
Samples for Testing
Program Website
 http://medent.usyd.edu.au/arbovirus/
 Results from sentinel chickens and mosquito monitoring
available and can be accessed through the above link.
 Weekly reports available online.
 Annual report, which summarises the whole season results
including human notifications is also available online.
 Great resource for information on mosquito species and
public health messaging.