- In Victoria, the most common pathogens transmitted from mosquitoes to humans are viruses such as Ross River virus and Barmah Forest virus
- Infections caused by Japanese encephalitis virus, Murray Valley encephalitis virus and Kunjin virus are rare, but do have the potential to cause severe disease.
- Avoiding mosquito bites is the most important way to prevent mosquito-borne diseases.
Since 1974, the Victorian Government has worked with other agencies including selected local governments to deliver an integrated mosquito management program.
This includes surveillance activities to monitor mosquito species and numbers and to test mosquitoes for viruses. Integrated mosquito management also includes mosquito control, investigation of mosquito-borne diseases in humans, and community education to reduce mosquito bites.
Funding to local councils
The Victorian Government provides funding to councils in areas at high-risk for mosquito-borne diseases to undertake mosquito surveillance and support mosquito management.
It is up to each council to determine the mosquito management measures best suited to their needs, but the focus is on reducing the risk of spread of mosquito-borne diseases, including Ross River virus, Japanese encephalitis virus and Murray Valley encephalitis virus. Activities generally include trapping adult mosquitoes and vector control.
About mosquito-borne diseases
More than 275 species of mosquitoes are found in Australia. Fortunately, only a few species bite humans, and fewer still are vectors of human diseases.
Other mosquito-borne diseases reported in Victoria are those acquired interstate or overseas (such as dengue fever).
The most effective way to reduce your risk of mosquito-borne diseases is by avoiding mosquito bites and removing mosquito breeding sites around your home.
Mosquito-borne diseases in Victoria
Japanese encephalitis (JE) is a rare but potentially serious infection of the brain that can be spread to humans through mosquito bites. There are currently no reported cases of Japanese encephalitis in Victoria.
More information on JE
Other resources for health professionals
Barmah Forest virus disease is caused by an alphavirus, which is spread by mosquitoes. Symptoms usually begin to appear between 7 to 10 (but up to 21) days after becoming infected, however many people infected with the virus do not develop any symptoms. Barmah Forest virus disease can cause joint inflammation and pain, fatigue and a rash of variable appearance.
Buruli ulcer (also known as Bairnsdale ulcer) is an infection of skin and soft tissue caused by the bacterium Mycobacterium ulcerans. There is increasing evidence that mosquitoes and possums play a role in transmitting the infection in Victoria.
Murray Valley encephalitis is a rare but serious illness caused by a flavivirus. Symptoms usually begin to appear between 7 to 12 days after becoming infected. Most people don’t have any symptoms, while others may develop a mild illness and make a full recovery. Murray Valley encephalitis can lead to brain damage or death in severe cases.
Dengue virus disease (dengue fever) is a viral disease spready by mosquitoes in many tropical and subtropical parts of the world, including Africa, Asia, South America, and occasionally some parts of northern Queensland.
Dengue fever ranges in severity from a mild flu-like illness through to a severe disease, and classically presents as an acute febrile illness of sudden onset. There is no specific treatment and no vaccine. Early diagnosis and management of symptoms is critical to reduce the risk of complications and avoid further spread of the virus.
Mosquito surveillance report
The department conducts mosquito surveillance throughout the Victorian mosquito breeding season, which in inland areas typically occurs from early November through to late April the following year, with coastal areas typically starting earlier and ending later.
This report contains a range of indicators relating to mosquito-borne diseases actively monitored by the Department of Health (the department).
The indicators used in this report are sourced from the following surveillance systems:
- Human surveillance (notified confirmed and probable cases and/or modelled predictions of vector-borne disease)
- Mosquito surveillance (adult mosquitoes)
Mosquito viral detections
As part of the mosquito surveillance program, captured mosquitoes are tested for Ross River virus (RRV), Barmah Forest Virus, Murray Valley encephalitis virus (MVEV), Japanese encephalitis virus (JEV) and West Nile/Kunjin virus. Table 1 lists all viral detections in mosquitoes for the 2022/2023 season.
The timing of detections of virus may be influenced by access to traps, transport of specimens, laboratory capacity and other factors. The accuracy of testing may be impacted by the number and location of traps, the number, type and condition of captured mosquitoes, as well as other factors. Note that virus may be circulating in Local Government Areas (LGAs) that are not listed as surveillance is only conducted on a sample of the overall mosquito population.
Table 1: Viral detections in trapped mosquitoes for the 2022/2023 season
Data is updated on a weekly basis or when there is a significant detection.
Changes to the Public Health and Wellbeing Regulations
On 14 December 2019, the Public Health and Wellbeing Regulations 2019 (the regulations) replaced the Public Health and Wellbeing Regulations 2009.
The new regulations will help reduce the risk of vector-borne diseases by broadening the scope of the existing regulations. They allow for the control of emerging and potential vector-borne disease risks.
In the summary, the changes include:
- replacing 'arbovirus infection control' with 'vector-borne infectious disease control' and broadening the scope of infectious disease control regulation to include other disease vectors, not just mosquitoes
- defining 'disease vector' so that an animal, including a bird or insect, can be the subject of infectious disease control
- establishing obligations on owners and occupiers of premises to take reasonable steps to control mosquito breeding grounds and abate conditions conducive to their establishment
- allowing an authorised officer to direct an owner or occupier of a premises to take steps to control any mosquito breeding ground and control the adult mosquito population on the premises
- introducing a Chief Health Officer authority to issue a disease vector control notice to address a material public health risk caused by a disease vector
- allowing an authorised officer to direct an owner or occupier of a premises to control a disease vector (as specified in a disease vector control notice).
What do the changes mean?
The new obligation on owners and occupiers of premises to control breeding grounds or abate conditions conductive to their establishment is based on taking reasonable steps to reduce risk.
This complements the existing non-regulatory measures to control mosquito breeding under the Victorian Arbovirus (mosquito-borne) Disease Control Program.
Disease vector control
It is intended that the Chief Health Officer would use the disease vector control notice in limited circumstances and only if satisfied a material risk (substantial risk of harm) to public health exists from a disease vector. This means in instances where a transmission risk is known to be connected in the community.
An example of when a disease vector control notice may be considered:
- Leptospirosis is an infectious disease that is transmitted from animals to humans. Common sources of infection are contact with the urine of infected animals and/or contaminated soil or water.
- Increases in Leptospirosis in a particular area of Victoria are often linked to rodent infestations. If a local community is affected, the Chief Health Officer could issue a disease vector control notice, which could require the introduction of specified rodent control measures.
- Local government affected community members and the department would work together to achieve disease reduction.
Reviewed 30 January 2023