Arboviruses from Mosquitoes: 8 Vector-Borne Viruses in Australia

Many people living with chronic fatigue, pain, joint aches and brain fog may be carrying undetected viruses that add to a larger jigsaw puzzle of underlying causes. In clinic, Amina often finds patients have had a past virus such as Ross River, Barmah Forest or Dengue, sometimes without ever knowing it. As mosquito numbers rise into summer, and with travellers returning from places like Indonesia with Dengue fever, it pays to be mindful of these infections.

Arboviruses are arthropod-borne viruses, and in Australia the most common carrier is the mosquito. Below are 8 vector-borne viruses found here, from the more familiar to the rare but serious.

The more common arboviruses

1. Ross River virus (RRV)

RRV is transmitted by female mosquitoes (not person to person), with symptoms appearing 3 days to 3 weeks after a bite. Many people never notice the bite at all. Some develop no symptoms, while others are knocked back hard. The most common picture is flu-like aches and joint pain (arthralgia) across the body, sometimes with a fever and a rash lasting about a week. Most people recover within a week, but those with a compromised immune system can take months to a year or longer. RRV is one virus Amina often sees on test results (IgG positive) in patients with chronic fatigue, signalling a past infection they were unaware of.

2. Barmah Forest virus

Similar to Ross River, and also spread by mosquitoes, though symptoms may not last as long, typically from a few weeks up to 6 months.

3. Dengue fever

Initial symptoms can appear 3 to 14 days after an infected mosquito bite and may last around a week. They include fever, body aches, headache, pain behind the eyes, rash, nausea, fatigue, swollen glands and bleeding from the nose or gums. Dengue viruses cause the most common arthropod-borne viral disease in humans, with an estimated 50 to 100 million infections each year, and it is one of the fastest-spreading tropical illnesses in the world. There are 4 dengue virus types (DENV-1 to DENV-4) in the Flaviviridae family.

Dengue can contribute to long-term fatigue in some people. The exact mechanism of post-dengue fatigue syndrome is not fully understood, but clusters of cytokines and host factors are thought to be involved. Catching different dengue types, even years apart, increases the risk of severe dengue, which can cause bleeding, shock, vomiting, stomach pain and breathing difficulties and can be life threatening. Deaths have occurred in Queensland from severe dengue.

Less common but potentially more severe

4. Murray Valley encephalitis virus

A mosquito-borne encephalitis virus found in New Guinea and Australia. Human cases occur sporadically, with epidemics in the Murray River Valley of south-eastern Australia in summer, typically after heavy rainfall and flooding. These conditions favour wading birds (the main reservoir) and the mosquito vector Culex annulirostris.

5. West Nile virus

Spread by infected mosquitoes, with most people having mild or no symptoms. Around 1 in 5 develop fever, and roughly 1 in 150 develop central nervous system disease such as encephalitis, meningitis or polio-like paralysis. Severe illness and death occur most often in the elderly. The incubation period ranges from 2 days to 2 weeks. Symptoms can include fever, fatigue, muscle aches, headache, back pain, sore throat, nausea, vomiting, diarrhoea, abdominal pain and rash.

6. Japanese encephalitis virus

Found in the Torres Strait Islands and the tip of far north Queensland, with symptoms similar to Murray Valley encephalitis virus.

7. Hendra virus

First identified in Hendra, Australia, in 1995 and recognised as a zoonotic disease of horses. It can cause fatal pneumonia and encephalitis in horses and humans. Fruit bats are the reservoir, and transmission requires close contact with infected horses or bat excrement. It is classified as a Hazard Group 4 pathogen, requiring the highest level of biosecurity.

8. Australian bat lyssavirus (ABLV)

A bat virus closely related to rabies, which does not currently occur in Australia. ABLV has been found in bat populations across several states and territories. Given the risk, all bats should be treated as potentially infected. Early symptoms are flu-like (headache, fever, weakness, fatigue) and can appear within days or up to several years after exposure, then progress rapidly. ABLV is transmitted through the saliva of infected bats via bites, scratches or contact with the eyes, nose, mouth or broken skin. If you have any contact with a bat, seek urgent medical care.

A supportive, whole-person approach

Herbal medicine, with immune-supporting and traditionally used anti-viral herbs, alongside nutrition and healthier lifestyle habits, may help build the immune system for stronger resilience. You can read more in Amina's notes on natural anti-viral support and immune support herbs. For lingering fatigue or undetected infections, a thorough consultation can help piece the puzzle together.

Prevention

Be mindful of mosquitoes. Close windows before evening or fit fly screens, use repellents, remove pooling water around the home to discourage breeding, and wear long sleeves and pants in forested or mosquito-prone areas.

This article is general information and not a substitute for individual advice. Please speak with a qualified practitioner about your own situation.