Mosquito-borne diseases

Workers can be exposed to mosquito-borne diseases such as Japanese Encephalitis and Ross River virus at work. Learn how to manage the risk of exposure in the workplace.

Mosquitoes can transmit serious diseases to humans through mosquito bites. There are different species of mosquitoes that are found in a range of locations in NSW. Different species of mosquitoes can spread different diseases.

Mosquito-borne diseases identified in NSW include:

Japanese encephalitis (JE)
Murray Valley encephalitis (MVE)
Kunjin virus
Ross River virus
Barmah Forest virus.

How are they spread?

Mosquito-borne diseases spread when a mosquito bites an infected animal or human and then bites a human. They are not spread from:

person-to-person
touching animals
eating animal products.

Who is at risk?

Workers in areas where mosquito-borne diseases have been detected are most at risk of exposure. The risk of exposure is higher near bodies of water, such as rivers and wetlands.

Mosquito activity increases after heavy rain and floods which can also increase the risk of exposure.

Managing the risk of exposure in the workplace

Persons conducting a business or undertaking (PCBU) must ensure the health and safety of workers and others at work by maintaining a safe workplace. This is the law. To manage the risk of exposure to diseases in the workplace, a PCBU must:

apply a risk management approach to eliminate or minimise exposure risks
consult with workers and/or their health and safety representatives.

If your workers carry out work in an area where a mosquito-borne disease is known to be present, it may not be possible to eliminate the risk of exposure. In this case, a PCBU must minimise the risk of exposure in the workplace so far as is reasonably practicable.

The best way to prevent mosquito-borne disease is to avoid mosquito bites. A range of control measures must be used to prevent mosquito bites to minimise the risk of exposure at work.

Environmental controls: Mosquito reduction

Mosquitoes lay their eggs on or in still and stagnant water.

They like to breed in warm conditions where there is excess water. There is often an increase in mosquito activity after heavy rain and flooding.

PCBUs can reduce mosquitoes in the workplace by:

Eliminating mosquito breeding sites

remove any debris which may collect standing water
improve water drainage where required.

Preventing mosquito entry

close windows, doors, vents, and other entrances
use insect screens to cover windows, doors, vents, and other entrances
install mosquito netting and screens in any accommodation provided to workers. This includes tents and other temporary structures.
use insecticide sprays, vapour dispensing units (indoors) and mosquito coils (outdoors) to clear rooms or repel mosquitoes from an area.

Personal protective controls: Bite prevention

Protect workers and others at the workplace from mosquito bites.

Clothing

Ensure workers cover exposed skin when working outside by wearing:

light-coloured, long, loose-fitting clothing
covered footwear with socks.

Insect repellent

Provide insect repellent. Ensure workers know how to apply it correctly to exposed skin.

The insect repellent should contain diethyltoluamide (DEET), picaridin, or oil of lemon eucalyptus.

Always check the label for reapplication times. Workers may need to apply repellent more often:

during hot weather
after strenuous activity and perspiration.

Apply sunscreen before repellent. DEET may reduce the effectiveness of sunscreen. As a result, workers may need to reapply sunscreen more often.

Limit exposure

Mosquitoes are most active at dawn and dusk. They are also active around swamps and wetlands.

Limit outdoor activity at these times and in these areas where possible.

Vaccination

Japanese encephalitis virus (JEV) is the only vaccine-preventable mosquito-borne disease in NSW.

Vaccination against JEV is recommended for those at high risk of exposure.

This includes the following groups:

People who work, live or are visiting a:
- Piggery (including farm workers and their families living at the piggery), pig transport workers, veterinarians (including veterinary students and nurses) and others involved in the care of pigs
- pork abattoir or pork rendering plant
People who work directly with mosquitoes through their surveillance (field or laboratory based) or control and management, and indirectly through management of vertebrate mosquitoes-borne disease surveillance systems (e.g. sentinel animals) such as:
- environmental health officers and workers (urban and remote)
- entomologists
All diagnostic and research laboratory workers who may be exposed to the virus such as:
- People working with JEV cultures or mosquitoes with the potential to transmit JEV.

A free JEV vaccine is also available for people who live or work in local government areas (LGAs) of high JEV concern.

See who is eligible for the JEV vaccination on the NSW Health website.

SafeWork NSW considers vaccination a high order risk control measure against disease.

Vaccination should be considered as part of a range of control measures available to minimise exposure to disease in the workplace so far as is reasonably practicable.

PCBUs should encourage eligible workers to protect themselves from infection through vaccination.

Vaccinated workers should still use precautions to avoid mosquito bites. The vaccine only protects against JEV.

Administrative controls

PCBUs must:

provide workers with information about the risks, symptoms, and treatments for mosquito-borne diseases.
train workers in how to use control measures, including how to wear personal protective equipment (PPE) and using repellent.

Types of mosquito-borne diseases

Japanese encephalitis

The Japanese encephalitis virus (JEV) causes a rare but serious disease called Japanese encephalitis (JE).

JEV spreads when a mosquito bites an animal infected with JEV (such as pigs or waterbirds) and then bites a human.

JEV has been detected in commercial piggeries and abattoirs in regional areas of NSW.

Those at higher risk of JEV infection include people who:

work at, visit of live near piggeries or other pig-related workplaces that have had positive JEV detections. This is because pigs can amplify the virus. Infected pigs have high levels of virus and can infect more mosquitoes when bitten.
work in the surveillance, control or management of mosquitoes and mosquito-borne diseases
work outside or do outdoor activities in high-risk areas or areas where JEV has been detected.

For more details, read the Japanese encephalitis fact sheet by NSW Health.

Also read the SafeWork NSW Japanese encephalitis safety alert.

Murray Valley encephalitis

The Murray Valley encephalitis virus causes a rare disease called Murray Valley encephalitis (MVE).

It spreads when a mosquito bites an infected animal (horses, kangaroos and non-water birds) and then bites a human.

This mosquito is common around the Murray Darling River basin areas in NSW during summer.

People in areas west of the Great Dividing Range are at higher risk of MVE infection, especially around rivers and wetlands.

For more details, read the Murray Valley encephalitis fact sheet by NSW Health.

Kunjin virus

Kunjin virus spreads when a mosquito bites an infected animal (waterbirds and horses) and then bites a human.

The mosquito is common in the Murray Darling River basin in NSW during summer and into autumn.

People in areas of rural NSW have a high risk of exposure, especially around:

rivers
wetlands
irrigated areas
flood waters.

For more details, read the Kunjin virus fact sheet by NSW Health.

Ross River virus

Ross River virus spreads when a mosquito bites an infected animal or human and then bites a human.

People in warm, humid climates near bodies of water have a high risk of exposure, especially around wetlands and rivers.

For more details, read the Ross River virus fact sheet by NSW Health.

Barmah Forest virus

Barmah Forest virus spreads when a mosquito bites an infected animal or human and then bites a human.

The mosquito is more common west of the Great Diving Range especially around wetlands or rivers.

For more details, read the Barmah Forest virus fact sheet by NSW Health.

Symptoms and treatment

Common symptoms of mosquito-borne diseases can include:

fever
chills
headache
muscle and joint pain / swelling
rash
fatigue.

Symptoms may appear 5-15 days after being bitten by an infected mosquito. Serious illness and hospitalisation from these viruses are rare.

JEV and MVE can cause a severe neurological condition called encephalitis. Symptoms may include:

severe headache
neck stiffness
coma
seizures
paralysis
sensitivity to bright lights (photophobia)
drowsiness and confusion
loss of consciousness

There is no specific treatment available for most mosquito-borne diseases.

If you believe you may be infected, seek medical help from your doctor. In an emergency, call Triple Zero (000) or visit your nearest emergency department.