Poliomyelitis

Polio was once a widespread and feared disease, causing significant morbidity and mortality worldwide. Thanks to widespread vaccination efforts, polio has been largely eradicated in many parts of the world. However, it remains endemic in a few countries and poses a potential threat of resurgence if vaccination rates decline. Understanding polio disease is crucial for continued global efforts for its eradication.

Poliomyelitis, often called polio or infantile paralysis, is a highly contagious disease caused by the poliovirus. This virus is an enterovirus, meaning it lives in the digestive tract. It typically enters the body through the mouth, multiplies in the intestines, and can then invade the nervous system. The polio virus attacks the motor neurons, which are nerve cells that control muscle movement. This attack can lead to muscle weakness and paralysis.

While most polio infections cause mild or no symptoms, a small percentage of cases can lead to paralysis, which can be permanent. The paralysis caused by polio can affect different parts of the body, including the legs, arms, and even the muscles responsible for breathing.

The World Health Organization (WHO) reports that global efforts to eradicate polio have been remarkably successful. Wild poliovirus cases have decreased by over 99% since 1988, with transmission limited to Afghanistan and Pakistan in 2023, down from an estimated 350,000 cases globally.

There are three serotypes of poliovirus, each causing the same disease but with varying degrees of severity:

• Type 1: The most common type, and the only type still in circulation in the wild. It is associated with paralysis.
• Type 2: Eradicated in 1999.
• Type 3: Last detected in 2020.

Polio can also be classified based on the severity of symptoms:

Non-paralytic polio (abortive polio)

This is the most common form of polio. It causes minor flu-like symptoms that usually last for a few days and then resolve completely. 

Paralytic polio

This is the most severe form of polio, occurring in less than 1% of infections. It causes paralysis of various muscle groups due to the virus attacking motor neurons in the spinal cord and brainstem. There are further sub-types of paralytic polio:

• Spinal polio: This is the most common type of paralytic polio. It affects the limbs, causing muscle weakness and paralysis. This can lead to difficulties with walking, standing, and using the arms and hands.
• Bulbar polio: This type affects the brainstem, which controls vital functions such as breathing, swallowing, and speaking. It can cause difficulty with swallowing, speaking, and breathing, and can be life-threatening.
• Bulbospinal polio: This is a combination of spinal and bulbar polio, affecting both the limbs and the brainstem.

Polio is caused by the poliovirus, which spreads primarily through the faecal-oral route. This means that the virus is shed in the faeces of an infected person and can be transmitted to others through:

• Contaminated food or water: This can occur when food or water sources are contaminated with faecal matter containing the poliovirus.
• Poor hygiene: The virus can also be spread through poor hand hygiene, such as not washing hands properly after using the toilet or before handling food.
• Contact with contaminated objects: Objects like toys or utensils can become contaminated with the virus and transmit it to others.

Less commonly, the virus can spread through:

• Respiratory droplets: An infected person can spread the virus through respiratory droplets produced when they cough or sneeze. However, this is a less common mode of transmission.

Most people infected with poliovirus have no symptoms (asymptomatic) or experience mild, flu-like symptoms that resolve within a few days. These may include:

• Fever
• Sore throat
• Headache
• Nausea and vomiting
• Fatigue
• Muscle weakness or stiffness

In a small percentage of cases (around 1%), the virus invades the nervous system, causing more serious polio symptoms, such as:

• Meningitis: Inflammation of the meninges, the membranes surrounding the brain and spinal cord. This can cause headache, stiff neck, and fever.
• Paralysis: Weakness or loss of muscle function, typically affecting the limbs, but can also involve the muscles responsible for breathing. The paralysis can be temporary or permanent.

Diagnosing polio involves a combination of:

Physical examination

The doctor will perform a physical examination to assess muscle weakness, reflexes, and other neurological signs. They will also look for signs of meningitis, such as a stiff neck.

Medical history

The doctor will ask about the patient's recent travel history, particularly to polio-endemic areas, and their vaccination status. They will also inquire about any recent illnesses or exposure to people who may have polio.

Laboratory tests 

• Stool sample analysis: This is the most common test used to diagnose polio. The presence of poliovirus in the stool confirms the diagnosis.
• Throat swab: A throat swab may also be used to isolate the virus, especially in the early stages of the illness.
• Spinal tap (lumbar puncture): In cases of suspected meningitis, a spinal tap may be performed to examine the cerebrospinal fluid for signs of infection.
• Blood tests: Blood tests may be used to rule out other conditions with similar symptoms.

There is no specific antiviral treatment that can cure polio. Treatment focuses on managing symptoms, providing supportive care, and preventing complications. This may include:

• Bed rest: Rest is important to allow the body to fight the infection and recover.
• Pain relievers: Over-the-counter pain relievers, such as ibuprofen or paracetamol, can help to reduce fever and relieve muscle aches and pains.
• Physical therapy: Physical therapy is crucial to help maintain muscle function, prevent muscle atrophy (wasting), and improve mobility. This may involve exercises, stretches, and the use of assistive devices.
• Respiratory support: In cases of paralysis affecting the breathing muscles, respiratory support may be necessary. This can involve mechanical ventilation or other breathing assistance.
• Managing complications: Treatment may also involve managing complications such as pneumonia, urinary tract infections, and bedsores.

Factors that increase the risk of polio include:

• Not being vaccinated against polio
• Living in or travelling to polio-endemic areas
• Poor sanitation and hygiene
• Weakened immune system

Polio can lead to serious complications, including:

• Permanent paralysis
• Deformities
• Breathing difficulties
• Post-polio syndrome: A condition that can develop years after a polio infection, causing muscle weakness, fatigue, and pain.
• Death

For individuals living with the effects of polio, these tips can help:

• Stay active: Engage in regular exercise and physical therapy to maintain muscle strength and flexibility. This can help to improve mobility, reduce fatigue, and prevent further muscle weakness.
• Use assistive devices: Utilise mobility aids, such as crutches, walkers, or wheelchairs, to improve mobility and independence. Braces or orthotics can also help to support weakened limbs and improve function.
• Manage pain: Explore pain management techniques such as medication, physical therapy, heat or cold therapy, and relaxation techniques to help manage pain and discomfort.
• Connect with support groups: Find support and share experiences with others affected by polio through support groups or online communities. This can provide emotional support, practical advice, and a sense of community.
• Monitor for post-polio syndrome: Be aware of the signs and symptoms of post-polio syndrome and seek medical attention if you experience any new muscle weakness, fatigue, or pain.

Polio only affects children.

While polio primarily affects children under 5, adults can also be infected, especially if they are unvaccinated.

Polio has been eradicated.

While polio has been eliminated in many parts of the world, it remains endemic in a few countries and poses a risk of resurgence if vaccination efforts are not maintained.

Polio only causes paralysis.

While paralysis is the most well-known symptom of polio, most people infected with the virus experience mild or no symptoms.

Seek medical attention immediately if you or your child experience any symptoms of polio, such as:

• Fever
• Muscle weakness or stiffness
• Headache
• Stiff neck
• Difficulty swallowing or breathing

This is especially important if you have recently travelled to a polio-endemic area or are not up-to-date on polio vaccinations.

• Am I up-to-date on my polio vaccinations?
• What are the signs and symptoms of polio that I should watch out for?
• What are the potential complications of polio?
• What are the best ways to manage the long-term effects of polio?
• What should I do if I think I've been exposed to polio?

• Provide emotional support: Offer encouragement, understanding, and a listening ear.
• Assist with daily tasks: Help with activities they may find difficult due to muscle weakness or paralysis, such as dressing, bathing, or cooking.
• Advocate for their needs: Help them access resources and support services, such as physical therapy, occupational therapy, and assistive devices.
• Stay informed about polio: Learn about the disease and its management to better understand their needs and provide informed support.
• Encourage social interaction: Help them stay connected with friends and family and participate in social activities.

Polio is a serious disease, but it is preventable through vaccination. Continued global efforts to vaccinate all children and maintain high immunisation rates are crucial to eradicate this disease and prevent its resurgence. For those living with the effects of polio, supportive care, rehabilitation, and community resources can help them to live full and productive lives.