Adelaide Mosquitoes and the Viruses They Transmit

Have you noticed that there have been more mosquitoes in Adelaide and South Australia this year?

You’re not alone - the rain and heat have created the perfect breeding conditions for mosquitoes, leading to a population explosion across the state.

SA Health are warning South Australians to avoid bites, as monitoring traps have detected more than five times the usual amount of mosquitoes carrying Ross River Virus and Barmah Forest Virus.

To help you better understand the risks, we’ve described in this article some of the mosquito borne viruses that can be transmitted.

You can also attend our general and childcare first aid courses in Adelaide for more information on identifying and treating mosquito bites.

Ross River Virus

One of the most common diseases spread by mosquitoes in South Australia is Ross River Virus (RRV).

Symptoms vary from person to person, but they may include:

• fever
• chills
• muscle aches
• rash
• fatigue
• aching tendons
• swollen lymph nodes
• headache, especially behind the eyes
• joint pain, swelling and stiffness

Joint pain is the most common symptom of RRV. The pain can be severe, and can affect any joint.

Pain and fever can be treated with paracetamol. However, there is no specific antiviral treatment for RRV, and there is no vaccine to prevent infection.

Barmah Forest Virus

Barmah Forest Virus (BFV) is another common mosquito borne disease.

Many people who become infected with BFV don’t have any symptoms. Symptoms that can develop include:

• rash, usually on the trunk or limbs
• joint pain, which may persist for more than 6 months
• tiredness and weakness
• joint swelling and stiffness
• flu-like symptoms, with fever, chills and headache
• muscle aches and pain
• swollen lymph glands

There is no specific treatment for BFV, however you can take paracetamol to help control fever and pain. Infected people typically recover within a few weeks, though symptoms have been known to persist for several months.

Murray Valley Encephalitis

Murray Valley Encephalitis (MVE) is a rare mosquito borne virus that is endemic in Northern Australia. However, there have been cases reported in South Australia.

MVE can have mild to severe symptoms.

The most common symptoms are:

• fever
• drowsiness (excessive sleepiness)
• confusion
• headache
• neck stiffness
• nausea and vomiting
• tremors
• seizures (fits)
• additionally in infants, irritability and floppiness

Many people can have no symptoms, or even mild symptoms, which include:

• headache
• nausea
• vomiting

MVE can progress to become quite severe. Symptoms of a worsening infection include:

• increasing confusion
• headaches
• drowsiness
• possible seizures indicating progression to meningitis (inflammation of the lining of the brain and spinal cord) or encephalitis (infection or inflammation of the brain)

MVE can be very dangerous, and there is no treatment or vaccine. Typically, when a person is diagnosed with MVE, they are quite sick and require hospital care until they have recovered. About 20% of those with severe, progressed MVE will die. About 40% will have permanent neurological damage.

Japanese Encephalitis

Japanese Encephalitis Virus (JEV) is a rare but serious mosquito borne virus that has only been known to be present in South Australia since February 2022.

There are typically no symptoms for JEV, though there may be minor symptoms like fever and headaches.

Some people can develop encephalitis, which is the inflammation of the brain. Symptoms of this include:

• tiredness
• fever and headache
• nausea
• vomiting or diarrhoea

If the encephalitis worsens, symptoms progress to become:

• confusion
• unusual behaviour
• sleepiness
• seizures
• weakness
• abnormal movements

There is no treatment for JEV, and typically those with a serious illness need hospital care.

However, those in high risk areas can receive a vaccine for JEV from SA Health.

West Nile Virus

West Nile Virus (WNV) is now also known as Kunjin, as Kunjin is considered to be a variant of WNV.

Most people with Kunjin/WNV have no or mild symptoms. However, symptoms can include:

• fever
• malaise (feeling of being unwell)
• headache
• muscle aches
• swollen lymph nodes
• fatigue
• rash
• swollen and aching joints

Infection can progress to encephalitis, though this is rare.

There is no treatment or vaccine for Kunjin/WNV, however it is typically milder than Murray Valley Encephalitis.

Prevention

South Australia’s Chief Public Health Officer Nicola Spurrier, says that the best protection from these mosquito borne diseases is prevention.

Mosquitoes are most active at dawn and dusk, so if you can, avoid being outdoors during these times. If you must be outside, wear long sleeved and light coloured clothing, and use insect repellent every time you go outside. The best mosquito repellents contain DEET, picaridin, or oil of lemon eucalyptus.

You can find more information for preventing mosquito bites in our Resource Library.

Final Thoughts

While mosquitoes in Adelaide will most commonly transmit Ross River Virus and Barmah Forest Virus, they have been known to transmit rarer and more severe diseases in South Australia. The best way to protect yourself against these diseases is to protect yourself from mosquito bites.

We also cover treatment of mosquito bites in our general and childcare first aid courses. We have training locations in Adelaide and in every other state, capital city, and major town throughout Australia.

Head to our website to enrol in a course near you today.