Arbovirus and mosquito monitoring reports

SA Health is the lead control agency in South Australia for human disease epidemics, including outbreaks of serious human arboviral disease. We work collaboratively with local councils (as relevant public health authorities for their areas) to support arbovirus prevention and mosquito surveillance and control programs.

Current hierarchy of response level 2 - Medium (September 2023)

On 30 August 2023 SA Health lowered the mosquito-borne disease threat level to 2 (medium) in South Australia. This was because long range BOM forecasts predict below median rainfall and above median maximum temperatures in South Australia for September to November 2023. These conditions usually correspond with reduced mosquito and arbovirus activity.

Recent arbovirus risk indicators

Murray Valley encephalitis virus (MVEV) was detected in mosquitoes trapped along the River Murray during January 2023 in the Renmark Paringa, Loxton Waikerie, Berri Barmera, Mid Murray and Murray Bridge council areas.

There was one confirmed human case of MVEV reported in South Australia in May 2023. MVEV was also detected in sentinel chickens in Mannum and Paringa in January 2023, and Clare, Qualco, Swan Reach and Meningie in February 2023.

West Nile virus Kunjin variant (WNV/KUN) was detected in trapped mosquitoes in the Loxton Waikerie council and Berri Barmera council areas and in a sentinel chicken at Clare in February 2023.

Japanese encephalitis virus (JEV) infection - There was one confirmed human case of JEV infection reported during the 2022/23 season (reported December 2022) who resides in the Riverland region.

Other mosquito-borne viruses being closely monitored are Ross River virus (RRV) and Barmah Forest virus (BFV). Very high detects of RRV and BFV in trapped mosquitoes were reported in South Australia during the 2022/23 season.

Mosquito surveillance

Approximately twenty councils in high-risk areas for mosquito-borne diseases currently participate in a mosquito surveillance program. Mosquitoes trapped are submitted to the Agriculture Victoria Research laboratory for mosquito species identification, counting and viral testing. Data is reported to SA Health for monitoring and analysis.

The absence of positive detections does not mean there are no infected mosquitos in the area. The risk of mosquito-borne disease is high across South Australia, so it’s important to *Fight the Bite and avoid being bitten.

Mosquito abundance

The table below shows the mean mosquito abundance data season-to-date. This is calculated by dividing the total number of mosquitoes caught across South Australia by the total number of traps set. It is intended to reflect trends in mosquito abundance across years. This measure accounts for any increases in the number of traps deployed and any increase in frequency of trapping.

*Updated monthly as 2023 data become available

Virus detections in trapped mosquitoes by Local Government Area (LGA)

The table below shows the LGAs where trapping is undertaken in South Australia and virus detections in trapped mosquitoes during the 2022/2023 season to date (September to April). Captured mosquitoes are tested for RRV, BFV, MVEV, JEV and WNV/KUN.

The absence of positive detections does not mean there are no infected mosquitos in the area. The risk of mosquito-borne disease is high across South Australia, so it’s important to Fight the Bite and avoid being bitten.

Sentinel chicken surveillance

Ten backyard chicken flocks of five chickens each have been established in South Australia to check for infection of JEV, MVEV and WNV/KUN. Blood samples are collected weekly from the chickens during peak mosquito season. The aim of the program is to monitor for viruses in the environment. Chickens are a good indicator of serious mosquito-borne disease risk to the community, as they readily produce antibodies to these viruses if infected, without developing symptoms.

The table below shows the locations where flocks are present in South Australia and virus antibody detections in chicken blood samples during the 2022/2023 season to date (September to April).

Monthly SA arbovirus and mosquito reports

The SA arbovirus and mosquito reports summarise the most recent available data to inform the current level of risk of mosquito-borne disease in SA. The reports detail:

• mosquito abundance at trapping sites
• arbovirus disease notifications
• arboviral detections in mosquitoes and sentinel chicken flocks
• meteorological data relevant to mosquito abundance.

Monthly reports

• April 2023 (PDF 427KB)
• March 2023 (PDF 372KB)
• February 2023 (PDF 474KB)
  
• January 2023 (PDF 400KB)
  
• December 2022 (PDF 454KB)
• November 2022 (PDF 500KB)
  
• October 2022 (PDF 405KB)

Graded response level

The data contained within the monthly reports determines the appropriate graded response in accordance with the SA Arbovirus Coordinated Control and Operations Plan (PDF 378KB) hierarchy of response. The Plan provides for the management of risks related to mosquito borne disease in SA. The hierarchy of response is dependent upon on-going data and trends identified by surveillance activities, weather forecasting and disease notifications. 

Annual reports

The South Australian Arbovirus and Mosquito Monitoring and Control Annual Report for the 2021-2022 season (PDF 1.7MB) summarises mosquito-borne disease notification data from South Australia, as well as the various mosquito surveillance and control activities undertaken by the Department for Health and Wellbeing and local health authorities across the state.

Previous reports

• 2020-2021 season — South Australian Arbovirus and Mosquito Monitoring and Control Annual Report (PDF 4MB)
• 2019-2020 season — South Australian Arbovirus and Mosquito Monitoring and Control Annual Report (PDF 4MB)