What is Poliomyelitis?
Poliomyelitis (polio) is a highly infectious disease caused by one of three wild poliovirus types (1, 2 & 3); it is spread through contact with infected faeces and nasal secretions/ saliva, or food contaminated with them. The disease was prevalent early last century, causing the deaths of many thousands of young children, until the introduction of an effective vaccine in the 1950s. Two of the wild virus strains – types 2 and 3 were declared eradicated by the WHO in October, 2019. Type 1 remains with us and continues to be reported from two countries – Afghanistan and Pakistan.
What are the symptoms?
The incubation period of polio averages from 7-10 days but can range anywhere from 3 days to over a month. Once ingested, the poliovirus multiplies in the intestines and, in the vast majority of cases, it produces no symptoms (it is excreted through the bowels for several weeks however). Around one quarter of those infected will report mild symptoms such as fever, headache, vomiting and tiredness which resolve after a few days. In a very small number of these cases the infection will spread to the central nervous system, resulting in meningitis or more seriously enter the brain stem or spinal cord resulting in “paralytic poliomyelitis” with characteristic asymmetric flaccid paralysis and loss of tendon reflexes. While the paralysis usually affects the legs, it can also spread to the chest muscles/ diaphragm with assisted ventilation required. Long term effects of polio for those who survive can include disability and post-polio syndrome.
The Salk vaccine of the 1950s was replaced by the live, oral Sabin vaccine (OPV), which had the advantage of being cheaper, easy to administer and provided herd immunity, but when the weakened poliovirus used in OPV is excreted for a period of time, in areas of poor sanitation and under-immunisation it can mutate and become capable of causing disease - circulating vaccine-derived poliovirus (cVDPV). The polio vaccine used now in Australia is IPV, an inactivated viral vaccine (IPOL or in various combinations).
In 2014, the WHO declared a Public Health Emergency of International Concern (PHEIC) under the International Health Regulations (IHR) and introduced temporary recommendations aimed at reducing the spread of poliovirus. Data on wild poliovirus (WPV1) and cVDPV are regularly reviewed to provide advice to the affected countries on management of cases and border controls. In some cases, travellers may require vaccination against polio in order to enter or leave a risk country – this would be documented with an International Certificate of Vaccination or Prophylaxis to record the vaccine dose and serve as proof of vaccination.
Where is it found?
The global incidence of polio has declined by around 99% since widespread vaccination programs were introduced and now the only endemic countries reporting wild poliovirus are Afghanistan and Pakistan. Due to the reasons previously explained, cVDPV has continued to cause infections in several regions across the globe including Africa, Asia and the Middle East.
Risk to travellers
The risk of polio infection in travellers is generally low, however vaccination is recommended if travelling to the affected regions, particularly in the case of travellers visiting friends and relatives, for stays of long duration, anyone having contact with a polio-infected person or visiting areas of poor sanitation.
Vaccination requirements may also be in place for some countries, according to outbreaks as specified by the PHEIC and there are several WHO member states that have mandated polio vaccination at border entry or departure.
Speak to your travel health doctor for the recommendations or requirements for your itinerary.
How is Poliomyelitis treated?
There is no cure for polio and any treatments are directed at limiting and alleviating symptoms.
What is Poliomyelitis Vaccination?
- Inactivated viral vaccine (IPOL)
- Inactivated vaccine in combination with Diphtheria/Tetanus/Pertussis and others (Infanrix Hexa, Infanrix IPV, Tripacel, Quadracel).
- Inactivated viral vaccine (IPOL)
- Inactivated vaccine in combination with Diphtheria/Tetanus/Pertussis (Adacel Polio/Boostrix IPV)
Australian children are vaccinated against polio using an inactivated vaccine (IPV) as part of the standard immunisation schedule – the primary series is given from 6-8 weeks of age with 3 doses administered at least 4 weeks apart. A booster at 4 years of age is the last scheduled vaccine dose.
Following the childhood series of polio vaccinations, boosters may be recommended every 10 years for travellers at risk, such as for travelling to polio endemic or epidemic countries, as well as healthcare workers or laboratory workers who may come in contact with poliomyelitis cases.
In order to comply with the temporary recommendations under the PHEIC, it may be necessary for some travellers to show proof of polio vaccination in the previous 12 months. Check with your doctor for more information.
Contraindications: Should not be administered to individuals who have previously experienced a serious reaction to this vaccine or those who are known to be hypersensitive to any of the vaccine components.
Level of protection
Possible Side Effects
Pain, redness or swelling at injection site occur in 10-15% of individuals but resolve in 3 days.
In young babies, decreased appetite, fever and crying.
As with all vaccines there is a small risk of an allergic reaction.
Australian Immunisation Handbook : https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/poliomyelitis