Poliomyelitis

What is Poliomyelitis?

Polio, short for poliomyelitis, is a contagious disease that spreads when people come into contact with the feces of an infected person. The disease initially grows in the lymphatic system, which is part of our body’s immune system. Between 1900 and 1950, there were many large outbreaks of polio, causing widespread illness and death among children. Since the 1980s, efforts to vaccinate people around the world have nearly wiped out polio.

Polio primarily affects countries that have unsanitary conditions. If healthcare providers are working in places where polio is still common, or if they’re treating patients who have recently traveled to those places, they should be alert for signs of polio. These signs can include flu-like symptoms followed by sudden paralysis. It’s important for medical professionals to test for polio as soon as possible, as it can cause permanent muscle weakness in some people if left untreated.

There’s also a related condition called Postpolio syndrome (PPS). This can cause progressive muscle weakness later in life in people who have previously had polio. It’s important to distinguish between polio and other viruses that can cause similar symptoms, especially in light of recent increases in polio-like illnesses in the US, such as those caused by the enterovirus-D68.

What Causes Poliomyelitis?

The poliovirus, which causes acute polio and postpolio syndrome, is part of a group called the Picornaviridae family and a species called the Enterovirus C. There are three types of the poliovirus found in the wild: Types 1, 2, and 3. Type 1 was responsible for most cases of paralysis from polio before vaccines came out. As of 2015, types 2 and 3 are considered wiped out.

Paralytic poliomyelitis, a severe form of polio, can sometimes happen due to a change in the oral polio vaccine (OPV) that makes it less effective. This is known as vaccine-associated paralytic poliovirus (VAPP), and it’s extremely unusual. VAPP happens roughly 3.8 times in every million cases in countries where the OPV is used. It’s usually linked with type 3 and is most common in people with weak immune systems. Some researchers believe that the risk of VAPP might be influenced by mother’s antibodies in the bloodstream and the timing of the first OPV dose.

Another possible cause of paralytic poliomyelitis is a vaccine-derived version. This could happen if the weakened virus in the OPV changes in a way that makes it stronger and allows it more readily to spread among people with low group immunity. Because of this risk, a global effort has been made to increase the use of the inactivated polio vaccine (IPV) and to remove type 2 from the OPV to create a bivalent OPV, which only contains types 1 and 3. In the United States, the IPV is the only available vaccine, and the CDC recommends four doses (see the treatment/management section for details).

Risk Factors and Frequency for Poliomyelitis

Poliomyelitis, more commonly known as polio, once caused permanent paralysis in nearly 1 out of every 200 patients. In 1988, there were a staggering 350,000 cases spread across 125 countries. In response, the World Health Assembly set goals to entirely wipe out wild-type polio. Since their initiative, only one type of wild polio remains, typically found in Pakistan and Afghanistan. However, isolated outbreaks continue to happen, like the one in Southeast Africa in late 2021 to early 2022, where 9 patients developed paralytic polio traced back to a virus from Pakistan.

In recent times, there has also been an increase in cases of a different kind of polio derived from oral vaccines, particularly in Sub-Saharan Africa and Asia. Challenges to combatting polio include difficulty in ensuring program compliance and reaching remote areas with healthcare services. Despite these hurdles, routine childhood vaccination has been instrumental in curbing the disease on a global scale. From the 350,000 cases in 1988, there has been a 99% decrease to just 33 cases in 2018.

Signs and Symptoms of Poliomyelitis

Paralytic poliomyelitis is a disease that can show itself through a combination of specific signs. Initial symptoms may include headaches, muscle pain, fatigue, nausea, stiff neck, or sore throat. In many instances, up to 75%, the disease does not show clinical symptoms. However, for many of those infected, about 95%, these symptoms appear but do not progress to paralysis. In contrast, about 5% may develop a type of brain inflammation known as aseptic meningitis.

If the illness progresses and affects the spinal cord, patients typically experience severe muscle spasms and pain before developing an uneven weakening of the muscles, known as flaccid paralysis. This form of paralysis often affects the lower limbs more than the upper ones. However, it’s important to remember that other kinds of viral infections can also cause this type of paralysis, and they tend to affect the upper body more.

Poliomyelitis tends to show itself in different stages:

• The acute stage – showcasing major symptoms like fever, stiff neck, muscle weakness, paralysis, and issues with involuntary body functions.
• The recovery stage – the severe symptoms disappear, and the muscles start to regain their function progressively. This improvement stage can last up to 2 years, with the most significant recovery occurring in 6 months.
• The residual paralysis stage – some of the paralysis remains, along with an imbalance in muscle strength and poor posture. Approximately 60% of patients have some remaining issues.

Testing for Poliomyelitis

If you have sudden weakness in your muscles, also known as acute flaccid paralysis, doctors will typically consider the possibility of viral meningitis. Viral meningitis is an infection that causes inflammation of the membranes around the brain and spinal cord. To confirm this, the healthcare professionals need to conduct a series of tests.

This testing often includes taking samples from the blood and your spinal fluid (which surrounds your brain and spinal cord), mucus from your nose or throat, and your stool. The samples will then be grown in a lab to see if any viruses, including the one which causes polio, show up. The test involves the usage of a tool called a polymerase chain reaction, which identifies the genetic material of the virus.

Additionally, you might also undergo an electromyogram, which is a test that measures the electrical activity of your muscles to ensure no other conditions are causing the weakness. Magnetic Resonance Imaging (MRI) of your brain or spinal cord could also be performed, to get a detailed picture of these areas and rule out other possible issues.

When it comes to post-polio syndrome, a condition that affects polio survivors years after recovery from an initial acute attack, there are currently no specific markers or indicators that doctors have widely accepted. Hence, diagnosis is often made by excluding other potential causes for symptoms. However, early research is on-going to identify potential disease markers for post-polio syndrome by testing spinal fluid using the polymerase chain reaction.

Treatment Options for Poliomyelitis

For poliomyelitis, or polio, care is focused on managing symptoms, because there isn’t a specific antiviral medication for this condition. In severe cases, where the disease causes paralysis, the majority of patients (60%) do not recover fully. The more intense the early stage of the disease, the greater the chance of lasting issues and the potential development of postpolio syndrome in the future.

Protection against polio is achieved by vaccination. There are two types: the inactivated polio vaccine (IPV) and the live-attenuated oral polio vaccine (OPV). The OPV is often used in developing countries because it is less expensive and easier to administer. However, there is a risk of Vaccine-Associated Paralytic Polio (VAPP) with the OPV. This means the vaccine, instead of protecting you, could potentially cause the disease. Therefore, the IPV is generally preferred for most immunization schedules. The OPV is being altered to remove a strain of the virus called type 2 to decrease the chance mutations of the virus that could lead to VAPP. In the US, only the IPV is available. Children typically get four doses of the IPV at specific ages, which is highly effective in protecting against polio. Adults who have been fully vaccinated but are traveling to areas where the virus is present are recommended to get one booster dose of IPV.

Managing symptoms, particularly joint stiffness, is crucial in treating polio. Various surgical options can help to restore balance in the muscles around a joint, which can prevent deformities. The aim is to help the patient regain the ability to walk and correct any factors that could lead to deformity as they age.

During the initial stage of the disease, treatment involves general care for fever and irritation, prevention of respiratory tract infections, and managing respiratory paralysis if it occurs. If the legs become paralyzed, they are supported with braces to relieve pain and muscle spasms. These braces also play an essential role in preventing deformities.

In the recovery stage, the goal is to help patients reach a physical state that permits them to be involved in their communities. Non-exhausting exercise programs are best for managing muscle overuse weakness. Orthotic devices, or braces, are useful in both temporarily and permanently treating many deformities and can be used on any part of the body.

What else can Poliomyelitis be?

While investigating cases of sudden muscle weakness or acute flaccid paralysis, doctors need to consider several possibilities, as this condition can be caused by both infectious and non-infectious factors.

Some of the infectious causes may include various types of viruses:

• Enterovirus A71
• Enterovirus D68
• Coxsackievirus A
• West Nile virus
• Varicella-zoster virus (which causes chickenpox and shingles)
• Japanese encephalitis virus
• Rabies virus

Conditions like Guillain-Barré syndrome should also be considered in the differential diagnosis.

However, not all causes of acute flaccid paralysis are due to viruses or other infectious diseases. Doctors are aware of several non-infectious conditions that could potentially lead to the same symptoms:

• Spinal cord infarctions (strokes)
• Acquired axonal neuropathies (nerve damage)
• Myasthenia gravis (a neurological disorder)
• Lambert-Eaton myasthenic syndrome (a rare autoimmune syndrome)
• Rhabdomyolysis (a condition where muscle tissue breaks down rapidly)

Differentiating between these diagnoses can be challenging. Doctors often rely on various clinical clues, such as examining if there was any injury to the affected limb or if the patient had experienced a prodromal illness (an early set of symptoms that might indicate the start of a disease before specific symptoms occur).

What to expect with Poliomyelitis

Polio symptoms can vary significantly from person to person. They can range from mild, flu-like symptoms with no paralysis to severe conditions like complete paralysis of all four limbs (quadriplegia) and even difficulty in breathing (respiratory failure). Those who only have mild viral symptoms are likely to fully recover.

However, if someone experiences sudden paralysis, the level of paralysis usually stays the same. It’s important to note that around 30% to 40% of people who had polio could develop postpolio syndrome – a condition that appears years after the initial polio infection. How and when this syndrome develops depends on multiple factors such as how severe the initial paralysis was, their age when they got polio, and even their socioeconomic status.

Possible Complications When Diagnosed with Poliomyelitis

The most severe problems resulting from polio infection are paralysis with involvement of the bulbar region of the brain, life-threatening failure of respiratory and cardiovascular systems, and a condition known as postpolio syndrome. Postpolio syndrome is characterized by new or worsening muscle weakness in a person who had previously been diagnosed with poliomyelitis. There are estimates suggesting that up to 40% of the 15 to 20 million known survivors of polio globally experience some form of postpolio syndrome. The usual symptom is new or worsening muscle weakness many years after the original infection. Other symptoms can include muscle pains, breathing difficulties, joint pain, muscle wasting, swallowing difficulties, and general tiredness. The exact cause of postpolio syndrome is unknown, and it is thought to occur due to overworking of remaining functional muscle units, inflammation in the brain or spinal cord, or degeneration of nerve-muscle connections. Complications of this syndrome could be respiratory failure, bone fractures, or failure to grow or thrive.

Key Complications of Polio:

• Paralysis involving the bulbar region of the brain
• Life-threatening failure of respiratory and cardiovascular systems
• Postpolio syndrome characterized by new or worsening muscle weakness
• Other symptoms of postpolio syndrome – muscle pains, breathing difficulties, joint pain, muscle wasting, swallowing difficulties, general tiredness
• Potential complications of postpolio syndrome – respiratory failure, bone fractures, failure to grow or thrive

Recovery from Poliomyelitis

Recovering from polio requires rehabilitation and teamwork from various medical professionals. This is especially important since 60% to 80% of patients who had polio have reported falling at least once in the past year. The main focus for treating post-polio syndrome includes individualized physical therapy, water-based exercises, endurance training, as well as pain management.

Doctors may recommend using specially designed braces to improve walking difficulties. In more severe cases, orthopaedic surgery might be considered to correct deformities and muscle imbalances. Certain antidepressant medicines, known as tricyclic antidepressants, are proven to be helpful in managing fatigue related to post-polio syndrome.

Post-polio syndrome can show up differently in each person, so each case should be carefully studied before treatment plans are started.

Preventing Poliomyelitis

It’s vital for patients to understand the importance of maintaining proper hygiene and getting vaccinated to prevent the spread of diseases. Lately, many communities worldwide have been resisting vaccinations, so it’s helpful to educate them about the dangerous effects that could occur if they don’t receive the polio vaccine. The Global Polio Eradication Initiative, in collaboration with the World Health Organization, US Centers for Disease Control (CDC), Rotary International, United Nations Children’s Fund, and the Bill & Melinda Gates Foundation, is actively working to eliminate polio around the world. They’ve developed an approach known as the Polio Endgame Strategy containing these main parts:

Regular Vaccination:

• The goal is to vaccinate more than 80% of all children in the first year of life.
• As part of the national immunization schedule, children should receive at least 3 doses of the polio vaccine (OPV or IPV following current CDC recommendations).

Extra Vaccination Activities:

• Large-scale vaccination campaigns, often known as National Immunization Days, are organized.
• These campaigns usually involve two rounds, one month apart.
• All children younger than 5 should get 2 doses of OPV, regardless of their previous vaccination history.

Monitoring:

• Efforts are made to identify every case of children with sudden muscle weakness known as acute flaccid paralysis.
• Stool samples from these children are collected and transported for analysis.
• Any isolated virus is identified and studied in laboratories.
• The virus is then tracked or mapped to trace outbreaks.

Targeted Measures: These are special measures taken like door-to-door campaigns in areas where polio infections are known or suspected to occur.