Weekly reports are available at: www.health.nsw.gov.au/Infectious/mosquito-borne/Pages/surveillance.aspx.
Please send questions or comments about this report to:
Surveillance and Risk Unit, Environmental Health Branch, Health Protection NSW: hssg-ehbsurveillance@health.nsw.gov.au
Testing and scientific services are provided by the Department of Medical Entomology, NSW Health Pathology, Institute of Clinical Pathology and Medical Research (ICPMR) for mosquito surveillance, and the Arbovirus Emerging Diseases Unit, NSW Health Pathology (ICPMR) for sentinel chicken surveillance.
The arbovirus surveillance and mosquito monitoring results in this report remain the property of the NSW Ministry of Health and may not be used or disseminated to unauthorised persons or organisations without permission.
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This section details detections of Murray Valley encephalitis virus, Japanese encephalitis virus, Kunjin virus, Ross River virus and Barmah Forest virus in the NSW Arbovirus Surveillance and Mosquito Monitoring Program.
Chickens are bled for detection of antibodies directed against Murray Valley encephalitis virus, Japanese encephalitis virus and Kunjin virus, indicating exposure to these viruses. Test results for the past week are shown in the map below and all positive test results for the season are detailed in the table. A positive test result indicates one or more chickens in a flock tested positive for the first time to antibodies directed against a particular virus, indicating newly acquired infection.
Sentinel chicken antibody test results for samples collected in the weeks ending 18 November 2023
There have been no detections in sentinel chickens in the 2023-2024 surveillance season.
Whole grinds of collected mosquitoes are tested for arbovirus nucleic acids to determine the presence of arboviruses in mosquitoes. Test results for detections of Murray Valley encephalitis virus, Japanese encephalitis virus, Kunjin virus, Ross River virus and Barmah Forest virus for the past week are shown in the maps below.
Test results for mosquito trapping sites reported in the week ending 18 November 2023
There were no arbovirus detections at inland sites in the week ending 18 November 2023. Mosquito trapping at coastal and Sydney sites will begin the first week of December 2023.
Inland
This section details counts of mosquitoes in the NSW Arbovirus Surveillance and Mosquito Monitoring Program. Each location represents the count average for all trapping sites at that location for the most recent week that collections were provided prior to preparation of this report.
Culex annulirostris and Aedes vigilax are vectors of interest for Ross River virus and Barmah Forest virus, Culex annulirostris is also a vector for Japanese encephalitis virus.
Mosquito counts (average per trap per location) for mosquito trapping sites reported in the week ending 18 November 2023
Inland sites
This section shows all mosquito trapping results by location and species type to date for the current arbovirus season.
Cumulative mosquito abundance tables
Mosquitoes require water to breed. Rainfall and tides (for the salt marsh mosquito, Aedes vigilax) are important contributing factors for proliferation of mosquito numbers. Unseasonably warm weather can also contribute to higher mosquito numbers.
In the week ending 18 November 2023, below average rainfall was observed along the coast, with low rainfall in other areas. In October, rainfall in NSW was predominantly average or below average, with some local areas around Deniliquin experiencing above average rainfall.
The Bureau of Meteorology’s rainfall outlook indicates that above-average rainfall is expected in NSW particularly in Western NSW and coastal areas south of Sydney.
In the upcoming week, minimum temperatures in NSW are expected to be higher than usual, especially in western NSW and along the Victorian border.
In the upcoming week, the maximum temperature levels are forecasted to be below average across NSW, with the exception of areas along the Victoria border where higher-than-average temperatures are expected.
Tidal information is relevant for the prediction of the activity of the salt marsh mosquito, Aedes vigilax. Typically for NSW, high tides of over 1.8 m, as measured at Sydney, can induce hatching of Aedes vigilax larvae. Predicted tide heights can provide some indication of when this is likely to occur.
Source: Australian Government, Bureau of Meteorology
Note: Measured tides at Sydney Port Jackson for the current week are available from the NSW Government, Manly Hydraulics
Laboratory: https://mhl.nsw.gov.au/Data-OceanTide.
Under the NSW Public Health Act 2010, human arboviral infections are notifiable in NSW.
https://www.health.nsw.gov.au/infectious/pages/data.aspx
Recent notifications of Ross River virus and Barmah Forest virus infections in humans (by date of case report received)
Notifications of Ross River virus and Barmah Forest virus infections, by month of disease onset (the earlier of patient-reported onset or specimen collection date), are available online at: www1.health.nsw.gov.au/IDD/pages/data.aspx.
The following figures show notifications for the current NSW Arbovirus Surveillance and Mosquito Monitoring season (2023-2024), and the same period in the previous four years.
Note: Presented human cases include both confirmed and probable cases.
Note: Presented human cases include both confirmed and probable cases.
