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Polio, short for poliomyelitis, is a highly infectious disease that most commonly affects children under the age of five. Polio is caused and transmitted by any of the three serotypes of the virus, poliovirus; a member of the Enterovirus genus. Poliovirus is transmitted via the faecal-oral route.

Symptoms vary widely between patients, with the majority of cases being asymptomatic or presenting with only mild, non-specific symptoms. However, in less than 1% of cases the virus infects the nerve cells of the spinal cord leading to paralysed limbs, or even death by immobilising the patient’s breathing muscles.

While there is no cure for polio, there are a number of safe and effective vaccines that prevent disease.

In 1988, with an estimated 350,000 cases of polio in 125 countries, the World Health Assembly together with Rotary International launched the Global Polio Eradication Initiative (GPEI) with the ambitious goal of eradicating the disease globally by the year 2000. The initiative is the largest public health initiative ever undertaken with more than 20 billion dollars contributed to the program as of 2022. The initiative is a public-private partnership led by WHO and national governments together with the following partners; UNICEF, the USA CDC, Rotary International and the Bill and Melinda Gates Foundation.

While the GPEI has not yet reached its goal of eradicating poliovirus, it has achieved great success, with the number of cases globally reduced by greater than 99%, and two of the three wild poliovirus serotypes (types 2 and 3) having been eradicated. The last case of wild poliovirus type 2 was seen in India in 1999 and the last case of wild poliovirus type 3 was seen in Nigeria in 2012.

Currently, only wild poliovirus type 1 continues to circulate, and only in the two remaining endemic countries of Afghanistan and Pakistan. Over the past three years we have been very close to interrupting transmission of wild poliovirus type 1, with only five, 22 and 12 cases detected across both countries in 2021, 2022 and 2023 respectively. However, 2024 is proving to be a challenging year for the program with a resurgence of cases in both counties, with 62 cases and 536 environmental detections reported this year. There is a real risk of re-established transmission in these countries.

Additionally, vaccine-derived polioviruses (VDPV) can arise when the attenuated poliovirus strains used in the oral polio vaccine are transmitted between unvaccinated people in a community with low vaccination coverage. Ongoing transmission allows the attenuated strains to mutate and potentially regain their ability to attack the central nervous system. In such cases, these circulating VDPVs (cVDPVs) can spread and cause paralysis just like wild poliovirus.

Unfortunately, cVDPV continues to cause more cases of paralysis than wild poliovirus each year, particularly across Africa. In 2024, 190 cases associated with cVDPV have been reported, including the first case in Gaza in more than 25 years and seven cases reported in Indonesia. Poliovirus anywhere remains a threat to children everywhere.

In this context, members of the GPEI have reaffirmed their commitment to eradicate the disease with the aim of interrupting wild poliovirus type 1 transmission by the end of 2025 and interrupting cVDPV transmission by the end of 2026.

Australia, together with other countries of the WHO Western Pacific Region was declared polio-free in 2000. The National Enterovirus Reference Laboratory (NERL) at the Peter Doherty Institute for Infection and Immunity, serves as the National Poliovirus Laboratory for Australia and the Pacific Island countries, and as a Regional Poliovirus Laboratory for the Western Pacific region. Through the ongoing testing of faecal specimens from cases of acute flaccid paralysis (a marker syndrome for poliomyelitis as well as a number of other conditions) and environmental samples, the NERL continues to maintain poliovirus surveillance for Australia and the region, ensuring we continue to remain polio-free.

On World Polio Day, support the global initiative to eradicate poliovirus by raising awareness of poliovirus as an ongoing public health threat, advocate and educate for the need for high vaccination rates, or donate directly to the program through Rotary International.