What is West Nile virus?
West Nile virus (WNV) is a mosquito-borne virus that can infect humans, birds, horses and other animals. People usually become infected after being bitten by a mosquito carrying the virus. The virus is found in many parts of the world, including North America, Europe, Africa, the Middle East and parts of Asia.
Human infections range from having no symptoms at all to serious neurological disease affecting the brain and nervous system. According to the World Health Organization (WHO), approximately 80% of people infected with West Nile virus never develop symptoms, while some experience a mild illness and a small proportion develop severe disease involving the central nervous system. There is currently no approved vaccine for humans, making mosquito bite prevention the most important form of protection for travellers.
FAQs
Which countries have West Nile virus?
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West Nile virus occurs across large parts of North America, Europe, Africa, the Middle East and Asia. Risk is generally higher in areas with active mosquito populations, particularly during summer and early autumn. Travellers should check local health updates before departure, especially if visiting rural, wetland or outdoor recreation areas.
Is there a vaccine for West Nile virus?
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There is currently no vaccine available to protect people against West Nile virus infection. Treatment is also limited to supportive care, which means preventing mosquito bites remains the best way to reduce your risk while travelling. Using insect repellent, wearing protective clothing and staying in screened or air-conditioned accommodation are key preventive measures.
Can I catch West Nile virus from another person?
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West Nile virus is not spread through everyday contact with an infected person. The virus is primarily transmitted through the bite of an infected mosquito that has previously fed on infected birds. Rare cases of transmission have occurred through blood transfusions, organ transplants and from mother to baby during pregnancy or breastfeeding, but these situations are uncommon.
Should I get travel health advice before my trip?
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If you are travelling to a destination with mosquito-borne diseases, it is a good idea to speak with your GP or a travel health clinic before departure. This is particularly important for older travellers, people with underlying health conditions, pregnant travellers and those spending extended periods outdoors. A healthcare professional can provide personalised advice on reducing mosquito exposure and other travel health risks.
What should I do if I become unwell during or after travel?
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If you develop symptoms such as fever, headache, muscle aches or a rash while travelling or shortly after returning home, seek medical advice and mention where you have travelled.
Urgent medical attention is recommended if you experience severe symptoms such as neck stiffness, confusion, weakness, tremors or other neurological symptoms, as these may indicate complications involving the nervous system.
What to Know
Symptoms of West Nile virus
Most people infected with West Nile virus are asymptomatic. When illness does occur, symptoms usually begin between two and fourteen days after being bitten by an infected mosquito, although this period may be longer in people with weakened immune systems.
The most common presentation is a mild illness often referred to as West Nile fever, with fever, headache, fatigue, body aches, muscle pain, joint pain, nausea, vomiting, diarrhoea and occasionally a skin rash. Most people recover completely, although tiredness and weakness may sometimes persist.
In fewer than 1% of infections, the virus can invade the nervous system and cause serious conditions, with symptoms including high fever, severe headache, neck stiffness, confusion, muscle weakness, tremors, seizures, vision problems, paralysis and coma. Older adults and people with compromised immune systems have a greater risk of developing severe complications.
Diagnosis and treatment of West Nile virus
West Nile virus can be difficult to diagnose based on symptoms alone because many mosquito-borne illnesses cause similar signs of infection. Doctors will consider a person's symptoms, travel history and potential exposure to mosquitoes when assessing the likelihood of West Nile virus infection. Laboratory testing is usually required to confirm the diagnosis.
Diagnosis is most commonly made through blood tests that detect antibodies produced in response to the virus. In patients with suspected neurological disease, testing of cerebrospinal fluid obtained through a lumbar puncture may also be performed. Additional testing may be required in some cases to rule out other infections with similar symptoms.
There is currently no specific antiviral medication that cures West Nile virus infection. Treatment focuses on managing symptoms and supporting recovery. People with mild illness can usually recover at home with rest, adequate hydration and medical advice as needed. Those with severe neurological disease require hospitalisation for intravenous fluids, respiratory support and close monitoring, often in an intensive care unit. Recovery from severe illness can take weeks or months, and some people may experience long-term neurological effects.
Prevention of West Nile virus
Because there is no West Nile virus vaccine for humans, prevention centres on avoiding mosquito bites. This is particularly important for Australian travellers visiting regions where the virus is known to circulate. Reducing exposure to mosquitoes is the single most effective way to lower the risk of infection.
Travellers should use insect repellent, wear loose-fitting long-sleeved clothing and long pants, and stay in accommodation with effective window screens or air conditioning whenever possible. If sleeping in areas without screened rooms, mosquito nets can provide additional protection. It is also important to limit mosquito breeding sites by avoiding areas with stagnant water where mosquitoes commonly reproduce.
Before travelling, Australians should review the latest destination-specific health advice and discuss any concerns with a healthcare professional, particularly if they have underlying medical conditions that could increase their risk of severe disease.