Mosquito-borne diseases

Key messages

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 West Nile/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.
Mosquito management is the responsibility of all landowners or land occupiers.

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.

All mosquito-borne diseases are notifiable to the department. For information on notification requirements and procedures, see Notifiable infectious diseases, conditions and micro-organisms

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.

For more information on how to avoid mosquito bites, see Mosquitoes can carry diseases on the Better Health Channel.

Mosquito-borne diseases in Victoria

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.
Ross River virus disease is caused by an alphavirus, which is spread by mosquitoes. Symptoms usually begin to appear 3 to 9 (but up to 21) days after becoming infected, and can include joint inflammation and pain, fatigue, muscle aches and a rash.
Japanese encephalitis (JE) is a rare but potentially serious infection of the brain that can be spread to humans through mosquito bites.
More information on JE
- Japanese encephalitis virus information for health professionals.
- Japanese encephalitis information for the public.
Other resources for health professionals
- Japanese encephalitis eLearning module for professionals
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.
- Information for health professionals about Murray Valley encephalitis.
- Information for the public about Murray Valley encephalitis.
West Nile/Kunjin virus infection is a rare but potentially serious illness caused by a flavivirus. It is related to the West Nile virus which is found in many parts of the world such as Africa, the Americas, Europe and Asia. Most people have no symptoms while others have mild illness. In rare cases of severe illness, it can lead to encephalitis and cause long term neurological complications or death.
- Information for health professionals about West Nile/Kunjin virus
- Information for the public about West Nile/Kunjin virus
Dengue virus disease (dengue fever) is a viral disease spread 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.
- Information for health professionals about Dengue fever.
- Information for the public about Dengue fever.

Mosquito management in Victoria

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.

For more information visit Mosquito management in Victoria.

Roles and responsibilities for mosquito control

In Victoria, the Public Health and Wellbeing Regulations 2019 (the Regulations) outline responsibilities for mosquito management. Mosquito management is the responsibility of all landowners or land occupiers. This applies to land owned/managed by both the public sector or government, or private residents, businesses and organisations.

For further information on the roles and responsibilities of the Department of Health, local councils and public sector and private landowners and land occupiers, see Mosquito management in Victoria.

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.

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.

For further information, see:

Vector-borne infectious disease control - Changes to the Public Health and Wellbeing Regulations

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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)

For more information, see Mosquito surveillance report.

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 (MVE) virus, Japanese encephalitis (JE) virus and West Nile (Kunjin) virus.