How Is Polio Caused?

Polio infections are rare, but a small number of cases still occur around the world. It is a disease caused by poliovirus, but can be prevented with the polio vaccination. The Global Polio Eradication Initiative, led by organisations such as the World Health Organization (WHO), UNICEF, Rotary International, and the Centers for Disease Control and Prevention (CDC) has made significant progress in reducing cases of polio. Lets take look at what polio is and its causes.

📝 What is polio and it’s causes?

Polio also called poliomyelitis is an infectious disease caused by any one of the three types of polio virus. There are three variations of poliovirus, called wild poliovirus type 1, 2 and 3 (WPV1, WPV2 and WPV3). Wild poliovirus type 2 was eradicated in 1999 and wild poliovirus type 3 was eradicated in 2020, but type 1 still exists.

These viruses can be found in the stools of people with polio for up to six weeks after the start of the illness. It primarily affects the nervous system, potentially leading to muscle weakness and paralysis. Polio is transmitted through contaminated water or food.

📝 How does the poliovirus infect someone?

The poliovirus is spread when food, water or hands contaminated with faeces, throat or nasal secretions of an infected person enter the mouth of an uninfected person.

A person may develop symptoms within 3 to 21 days of coming into contact with the virus and will be most infectious 7 to 10 days before and after the beginning of symptoms.

People remain infectious for as long as the virus continues to be excreted in their faeces, which may continue for up to 6 weeks. Typically, the virus remains in the throat for 1 to 2 weeks.

📊 What are the symptoms of polio?

Between 70% and 95% of people infected with poliovirus don’t have symptoms. Of those with symptoms, most people have the mildest form (abortive poliomyelitis) and flu-like symptoms. The most severe symptoms are seen with paralytic polio, causing paralysis.

Poliovirus infection is classified into three main types based on the severity of the disease and its symptoms.

Symptoms of abortive poliomyelitis

Abortive poliomyelitis symptoms are mild symptoms similar to many other illnesses like the flu. Symptoms start three to seven days after getting infected and last a few days. Symptoms of abortive poliomyelitis include:

• Fatigue
• Fever
• Headache
• Vomiting
• Diarrhoea or constipation
• Sore throat

Symptoms of non-paralytic poliomyelitis

Non-paralytic poliomyelitis starts with the same symptoms as abortive poliomyelitis. Non-paralytic polio, also known as aseptic meningitis symptoms, progress on to:

• Neck stiffness
• Pain or pins-and-needles feeling in your arms and legs
• Severe headache
• Sensitivity to light

Symptoms of paralytic poliomyelitis

Paralytic poliomyelitis starts out with symptoms similar to abortive poliomyelitis or non-paralytic poliomyelitis. It can attack the brain and spinal cord. Luckily less than 1% of people with polio get paralytic poliomyelitis. Symptoms include:

• Sensitivity to touch
• Muscle pain
• Spinal poliomyelitis, preventing movement of arms or legs or both (paralysis)
• Bulbar poliomyelitis makes it hard to breathe, swallow and speak. If the breathing muscles are affected, it can be life threatening
• Bulbospinal poliomyelitis has symptoms of both spinal and bulbar polio

🏥 Diagnosis of polio

To diagnose polio, your healthcare provider will:

• Take your medical history
• Carry out a physical examination
• Rule out other possible explanations for symptoms
• Test for the poliovirus in samples of throat secretions, faeces and cerebrospinal fluid (the fluid surrounding the brain and spinal cord)

❗Risk factors for polio

You are most at risk of infection with the poliovirus if you are unvaccinated against polio. High risk groups for infection include:

• Very young children under 5 years of age
• Pregnant women
• Elderly people
• People with a weakened immune system
• Travelling to an area where polio is common or where an outbreak has recently occurred

💊 Treating polio

There’s currently no cure for polio. Treatment focuses on supporting bodily functions and reducing the risk of long-term problems while the body fights off the infection.

This can include bed rest in hospital, painkillers, breathing support and regular stretches or exercises to prevent problems with the muscles and joints.

If you’re left with long-term problems as a result of a polio infection, you’ll probably need ongoing treatment and support.

This may include physiotherapy to help with any movement problems, devices such as splints and braces to support weak limbs or joints, occupational therapy to help you adapt to any difficulties, and possibly surgery to correct any deformities.

❗Complications caused by polio

Polio often passes quickly without causing any other problems, but some people are left with persistent problems. About 1 in every 200 people with the infection will have some degree of permanent paralysis, and others may be left with problems that require long-term treatment and support.

These can include:

• Muscle weakness
• Shrinking of the muscles (atrophy)
• Tight joints (contractures)
• Deformities, such as twisted feet or legs

There’s also a chance that someone who’s had polio in the past will develop similar symptoms again, or worsening of their existing symptoms, many decades later. This is known as post-polio syndrome.

💉 Can polio be prevented?

Immunisation is the best protection against polio. The best way to prevent polio is to make sure you and your child are up to date with your vaccination schedule. Infectious disease experts recommend children receive their routine vaccinations to protect them from serious life-threatening diseases and their complications.

Two types of vaccine are available: An inactivated poliovirus vaccine (IPV) and a live attenuated oral polio vaccine (OPV). Inactivated polio vaccine is injected intramuscularly and recommended by the CDC and the NHS. Oral poliovirus vaccine is still used in endemic areas such as Afghanistan and Pakistan. Experts now recommend that the OPV not be given and that only IPV be used.

📍 Where is polio found?

Polio still exists in some parts of the world today, but significant progress has been made in reducing its prevalence through polio vaccination efforts.

Areas declared polio-free by the World Health Organization (WHO) include Europe, the Americas, the western Pacific region and, most recently, southeast Asia. However, polio is still a significant problem in Afghanistan, Nigeria and Pakistan, and there’s a potential risk of infection in other parts of Africa and some Middle Eastern countries.

📝 Conclusion

Vaccinations have eliminated polio in many parts of the world, but it is not completely eradicated. As long as polio still exists in any part of the world, it can come back and cause severe illness in those who aren’t protected by vaccination. The best way to protect yourself and your community is to get vaccinated.

If you have not been vaccinated, have been exposed to polio and are showing symptoms or have questions or concerns around vaccination or getting your child vaccinated, contact your healthcare provider.

Sources

• Polio – NHS
• Poliomyelitis
• NaTHNaC – Poliomyelitis
• Polio – NHS inform
• Polio – Symptoms and causes – Mayo Clinic
• Polio: Virus, Causes, Symptoms, Transmission & Treatment
• Disease factsheet about poliomyelitis