Are you planning a trip to Asia or northern Africa but worried about Poliovirus outbreaks? Don’t worry, we’ve got you covered!

This article will help you understand the steps to manage a poliovirus outbreak when travelling to an area with one.  

What is polio?

Polio or Poliomyelitis is a viral disease that affects the central nervous system (brain and spinal cord) and causes paralysis, the inability to move some or all limbs. ‘Poliomyelitis’ is a Greek word where ‘polio’ means ‘grey’ and ‘myelon’ means ‘marrow’.¹ It means inflammation of the spinal cord (grey matter). 

It is caused by Poliovirus, which is transmitted from person to person via the faecal-oral route and contaminated food and water. Humans are the only hosts of this virus, meaning Poliovirus replicates and spreads infection exclusively in humans. 

Types of poliovirus

There are 3 types of Poliovirus:

• Wild Poliovirus (WPV)
• Vaccine-derived Poliovirus (VDPV)
• Sabin-like Poliovirus (SL)

Wild poliovirus (WPV)

It is the naturally occurring form of Poliovirus. Based on slight changes in their structure, they have three further 3 serotypes (classification given to microorganisms with the same arrangement, type, and number of surface antigens): 

• Type 1 (WPV1): Currently endemic in Afghanistan and Pakistan.⁵
• Type 2 (WPV2): Declared eradicated (completely eliminated from the world) in September 2015
• Type 3 (WPV3): Declared eradicated in October 2019

Vaccine-derived poliovirus (VDPV) 

During oral polio vaccination (OPV), weakened Poliovirus is administered to the body, leading to the formation of antibodies as the body’s defence mechanism against the virus. 

In rare cases, vaccinated individuals can pass the weakened virus in their stools, which may circulate in communities with low vaccination coverage and poor sanitary and sewage systems.  

This strain of Poliovirus is called vaccine-derived poliovirus.

Sabin-like poliovirus

The vaccine-derived Poliovirus strains that vary slightly in genetic material (<1% nucleotide sequence difference) are called Sabin-like.²

Symptoms 

Poliovirus mainly affects children under the age of 5 years. However, any unvaccinated person is prone to contracting the infection irrespective of their age.

About 70% of people exposed to Poliovirus are asymptomatic, meaning they do not show any symptoms. The remaining 25% of patients show paralysis. 

Paralytic poliomyelitis can present in one of three forms:^1,7

• Spinal poliomyelitis: Most common form. It affects the muscles supplied by the motor neurons of the spinal cord
• Bulbar poliomyelitis: Maximum fatality due to the involvement of the brainstem neurons. It damages the nerves that control swallowing and talking, resulting in the pooling of secretions in the throat and death by suffocation or respiratory failure
• Bulbospinal poliomyelitis: a combination of the above 2. It involves the spinal cord and the brainstem. The symptoms include difficulty breathing, swallowing, and the paralysis of arms and legs

Paralytic cases of polio show various symptoms such as:

• Fever
• Headache
• Sore throat
• Mild respiratory tract infection
• Stomach pain
• Loss of appetite
• Muscle spasms of the neck, back and lower limbs
• Muscle pain
• Muscle weakness
• Osteoarthritis (joint deterioration)
• Skeletal deformities
• Aseptic meningitis
• Fatigue
• Nausea
• Vomiting

Risk factors for travellers

Exposure to infected populations

Travelling to areas with infected populations directly increases the risk of contracting infection. As it is rightly said, “prevention is better than cure”, it is best to avoid places with polio outbreaks, especially with children who are prone to polio infection. This includes places like Algeria, Angola, Botswana, Cameroon, Egypt, Nigeria, Tanzania, Zambia, Zimbabwe, Tajikistan, Afghanistan, Pakistan and China.

Poor sanitation and hygiene

Polio is a contagious disease which spreads from person to person due to close contact. It usually spreads through the faecal-oral route and contaminated food and water, meaning the disease can be transmitted from an infected person to close contact by sharing food, clothes, utensils or other commodities. 

If hands are not washed properly, touching contaminated surfaces such as bathroom fixtures and towels can spread the virus. 

In areas with poor sewage systems and a lack of waste management, faecal matter containing the Poliovirus can enter water bodies and public water systems, spreading the disease. 

Low vaccination coverage

When a large proportion of the population is vaccinated against a disease, the disease can not spread to a large extent because most of the population is protected. This helps protect other people who can’t be vaccinated, such as newborn babies, immunodeficient individuals, the elderly and people with pre-existing medical conditions such as HIV-AIDS, cancer, or intestinal disorders. This immunity protects the community as a whole, hence it is called ‘Community immunity’ or ‘Herd immunity’.

A vaccine is the most important step in preventing polio. Low vaccination coverage in a population obstructs the achievement of herd immunity, which could be a risk to the traveller. 

Movement to regions with inadequate healthcare infrastructure

Resources and access to medical care are limited in areas with insufficient healthcare infrastructure. The traveller may be unable to obtain immediate medical aid in case of Poliovirus infection. 

Preventive measures for travellers

Identify high-risk regions  

Travellers are advised to assess travel risk before planning a trip. You can identify high-risk regions using the World Health Organisation (WHO) and Centres for Disease Control and Prevention (CDC) websites.

Click here to check: Outbreak countries and Endemic countries

Click here to check: Polio cases worldwide

Consulting travel advisories

Certain government and health organisations, such as the CDC and WHO, regularly update travel advisories on their websites. 

Make sure to check for any updates before the trip.

Check Global Polio - Level 2 - Level 2 - Practice Enhanced Precautions - Travel Health Notices for more information on travel updates. 

Vaccination is the primary preventive measure

Vaccination is the most effective and the only method to prevent polio. A vaccine contains killed or weakened pathogens, the organisms that cause diseases. The body’s natural immune system fights against these weakened pathogens, which are incapable of causing the disease. Our immune system remembers the disease. Hence, whenever your body is exposed to a virulent (harmful) pathogen, it recognises the pathogen and destroys it, protecting you from the disease. 

Importance of vaccination

Once contracted, polio cannot be cured. The symptoms may vary from mild flu-like to paralysis. After exposure to Poliovirus, the symptoms might appear from 3-6 days to a few weeks.

However, if you are vaccinated, your risk of contracting Poliovirus is reduced by 99% to 100%.⁸

Types of vaccines

There are two types of polio vaccines: Oral Polio Vaccine (OPV) and Inactivated Polio Vaccine (IPV) 

Oral Polio Vaccine (OPV)

• As the name suggests, the oral polio vaccine is administered orally as liquid drops
• It contains a live, weakened pathogen
• It is also known as the Sabin vaccine
• It provides systemic immunity (immunity through the production of antibodies in the bloodstream) and gut immunity (inhibiting Poliovirus replication in the intestines)
• In rare cases, the live pathogen can mutate and cause polio
• Oral polio vaccine is indicated for outbreak control, herd immunity, and mass immunisation

Inactivated Polio Vaccine (IPV)

• It contains killed or inactive pathogens, hence the name Inactivated Polio Vaccine
• It is administered through an injection in the arm or leg muscles
• It is also known as the Salk vaccine
• It provides systemic immunity but not gut immunity (see above) 
• Since it contains killed pathogens, there is no risk of Vaccine-Derived Poliovirus (VDPV)
• The inactivated polio vaccine is indicated for routine immunisation and in individuals with medical conditions. 

Polio vaccination schedule

The Centres for Disease Control and Prevention (CDC) recommends 4 doses of the routine polio vaccination for children at the age of:

• 2 months
• 4 months
• 6 to 18 months
• 4 to 6 years

For travelling children, the schedule is accelerated as follows:

• 1^st dose at 6 weeks
• 2^nd dose at 4 or more weeks after 1^st dose
• 3^rd dose at 4 or more weeks after 2^nd dose
• 4^th dose at 6 or more months after 3^rd dose

If you are an adult who was fully vaccinated in childhood, do not worry at all! You are safe.

If you are vaccinated but at increased risk of contracting Poliovirus, you may receive one lifetime IPV booster dose.

If you are an unvaccinated adult, you may receive:

• 1^st dose at any time
• 2^nd dose 1-2 months after 1^st dose
• 3^rd dose 6-12 months after 2^nd dose

Read more here: CDC’s Polio Vaccine Recommendations

Pre-travel health tips

Here is a checklist for all your pre-travel requisites to ensure a safe trip:

• Consult a healthcare provider for medical check-ups and personalised risk assessment. Discuss a detailed account of your medical history and the risks involved
• Do not forget to pack your International Certificate of Vaccination or Prophylaxis (ICVP), also called Yellow Card
  Countries such as India, Pakistan, Syria, Somalia, Mozambique, Madagascar, and Nigeria require proof of vaccination before border entry
  You can check if your destination requires a certificate on the CDC’s Travel Health webpage
• Always ensure your health insurance covers Poliovirus-related medical needs or other medical treatment abroad
• Practice hygiene and sanitation practices during travel. Wash hands frequently with soap and water
  Always lather your palms, the back of your hand, between the fingers and under the nails properly
• If the soap and water are unavailable, use a hand sanitiser with 60%-95% alcohol.³ Cover all surfaces of both your hands until they dry
  Note: Hand sanitisers do not work on visibly dirty or greased hands
• Avoid contaminated water and food. Countries such as India and Pakistan are well known for their street food. While it may be tempting to try some, it is best to avoid street food or uncooked meals⁴
• Drink boiled or bottled water. Boiling water kills germs and pathogens and helps prevent waterborne diseases such as polio
• Always use clean and well-maintained public restrooms. Use toilet seat sanitisers or covers wherever possible. This also helps prevent Urinary Tract Infections (UTI) and other infections

What if I contract poliovirus during travel?

• Knowledge and awareness about polio can help you recognise the symptoms of polio
  The early signs include headache, fever and fatigue. The late signs include stiffness and paralysis
• In case polio symptoms appear, seek immediate medical help from the nearest health facility
• Since polio is contagious, you must report it to local health authorities for containment
• Adequate rest and gentle exercise can help slow down progressive muscle weakness and pain. Avoid any unnecessary physical strain
• Eat a healthy, balanced diet that provides energy
• Always follow up with your healthcare provider post-travel to high-risk areas
• Cooperating with healthcare authorities is necessary to contain the virus and prevent its spread. With contact tracing, quarantine and targeted vaccination, we can protect vulnerable populations from polio and restrict the spread to polio-free regions

Summary

Polio is a highly contagious viral disease that spreads via the faecal-oral route and contaminated food and water. The symptoms may vary from mild flu-like to paralysis. It cannot be cured but prevented by immunisation. There are two types of vaccines against Poliovirus: Oral Polio Vaccine (OPV) and Inactivated Polio Vaccine (IPV). If you are planning to travel to regions with Poliovirus outbreaks, you must ensure you’re fully vaccinated and well-informed about travel advisories. Practice effective hygiene and sanitary measures to prevent contracting polio. If you suspect Poliovirus symptoms, inform local healthcare authorities for containment, contact tracing and targeted vaccination to prevent further spread of polio. With such measures, you can ensure a happy and safe trip.