What is Polio?
Poliovirus is a highly contagious virus that causes poliomyelitis (polio), an infection that can affect the nervous system and, in severe cases, lead to permanent paralysis or death. Although Australia has been declared polio-free since 2000, the virus continues to circulate in several parts of the world, meaning that international travel remains a potential source of exposure for Australians.
Transmission occurs primarily through the faecal–oral route, most commonly via contaminated food, water, or unwashed hands. After entering the body, the virus multiplies in the gastrointestinal tract. In a small proportion of cases, it spreads to the central nervous system, where it damages nerves responsible for muscle movement.
A defining feature of poliovirus infection is that most individuals experience no symptoms at all. Despite this, they can still shed the virus and contribute to its spread, particularly in settings with poor sanitation. The virus can also persist in the environment for prolonged periods, which facilitates ongoing transmission in endemic or outbreak settings.
The World Health Organisation (WHO) reports that since the launch of the Global Polio Eradication Initiative in 1988, cases of wild poliovirus have decreased by more than 99%. From an estimated 350,000 cases per year across more than 125 countries in 1988, significant transmission now occurs in a very limited number of countries.
FAQs
Do I need a polio vaccine or booster before travelling from Australia?
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Most Australians are vaccinated against polio in childhood through the National Immunisation Program. However, if you are travelling to a country where there is a risk of poliovirus, a booster dose may be recommended if it has been more than ten years since your last vaccination. It is advisable to discuss this with a doctor before departure.
Which destinations pose a risk for poliovirus?
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Polio remains endemic in Afghanistan and Pakistan, and outbreaks continue to occur in Asia, Africa, the Middle East and other parts of the world. Risk is generally higher in areas with limited sanitation and lower vaccination coverage. Discuss your travel destinations with a travel doctor to determine your level of risk.
Can I still get polio if I am fully vaccinated?
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Vaccination provides very strong protection against severe disease, particularly paralytic polio. However, it does not always completely prevent infection. In rare cases, a vaccinated person may carry the virus without symptoms and potentially transmit it to others. Maintaining good hygiene practices while travelling remains important.
What should I do before travelling to reduce my risk?
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Before travelling, you should ensure your routine vaccinations, including polio, are up to date. A travel health consultation is recommended several weeks before departure to assess your individual risk. In addition to vaccination, you should follow safe food and water practices and maintain good hand hygiene while overseas to reduce the likelihood of exposure.
Are there any side effects from the polio vaccine?
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The polio vaccine is generally very safe, with most people experiencing only mild and short-lived side effects, such as soreness, redness, or swelling at the injection site. Some individuals may feel slightly tired, have a low-grade fever, or experience mild discomfort for a day or two after vaccination.
Serious side effects or allergic reactions are rare, as reported in the Australian Immunisation Handbook. In Australia, the inactivated polio vaccine (IPV) is used, which contains killed virus and cannot cause polio.
What to Know
Polio symptoms
The clinical presentation of poliovirus infection varies widely. Most infections are asymptomatic, which is one of the reasons the virus can spread undetected. When symptoms do occur, they are usually mild and resemble a non-specific viral illness.
Patients may experience fever, fatigue, headache, sore throat, and gastrointestinal symptoms such as nausea, vomiting, or abdominal discomfort. These symptoms typically resolve without complications.
In a smaller proportion of cases, the infection progresses to involve the nervous system. This may present with symptoms such as neck stiffness, severe headache, or muscle pain. In rare instances, the virus causes paralytic polio, characterised by the sudden onset of flaccid muscle weakness, most commonly affecting the lower limbs.
Although paralytic disease occurs in less than one percent of infections, it can have lifelong consequences. In the most severe cases, involvement of the respiratory muscles may lead to breathing difficulties and can be fatal.
Polio diagnosis and treatment
The diagnosis of poliovirus infection relies on laboratory testing, most commonly through detection of the virus in throat swabs and stool samples. In Australia, testing is highly specialised and coordinated through reference laboratories, with any suspected case managed as a public health priority.
There is no specific antiviral treatment for poliovirus. Management is supportive and focuses on relieving symptoms and preventing complications. This may include pain management, physiotherapy to support muscle function, and, in severe cases, respiratory support.
Given the absence of a curative treatment, prevention through vaccination and public health measures remains the cornerstone of management.
Polio prevention
Prevention of poliovirus infection is centred on vaccination, which is safe, highly effective, and included in Australia’s National Immunisation Program. For travellers, ensuring that vaccinations are up to date is the most important step in reducing risk. A booster dose is recommended for those travelling to areas where poliovirus is circulating if their last dose was more than ten years ago.
In addition to vaccination, attention to hygiene plays a critical role. As the virus spreads via contaminated food and water, travellers should take care to consume safe drinking water, avoid high-risk foods, and practise regular handwashing, particularly before eating.
The risk of exposure is higher in areas with poor sanitation, overcrowding, or active outbreaks, making environmental awareness paramount. Australian public health authorities maintain surveillance systems, including wastewater monitoring, to detect any reintroduction of poliovirus and respond rapidly to protect the community.