Introduction

Polio, also called poliomyelitis, is a disease caused by the poliovirus, which is very infectious and commonly affects infants. This virus belongs to the Picornaviridae family and spreads rapidly, mostly via the fecal-oral transmission route through contaminated water and food.^1,2

Understanding the long-term effects of polio, particularly on physical development and mobility in children who survive the acute phase, is crucial. This is because these may lead to a degree of paralysis¹ and additional symptoms like muscle weakness, fatigue, and pains arising from the damage the poliovirus causes to the motor neurons of the child’s body.³ These symptoms are often collectively called Post-Polio syndrome, which tends to surface years after the initial recovery from the polio disease.^1,3 

Diving into the impact polio has on survivors helps healthcare professionals address health-related consequences linked to polio and design interventions to help eradicate polio,  understand the long-term consequences, and increase the vaccination rate among infants. 

Overview of the acute phase of polio

The acute phase of polio has different stages in the disease progression. This phase includes the incubation period, the initial symptoms, and disease progression to paralysis.⁴ 

1. The incubation period varies, but it usually ranges from 7-10 days. During this period, the virus gets into the body through the mouth and then replicates in the intestinal tract, before potentially causing an attack on the nervous system
2. Initial symptoms are subsequently experienced after the incubation period, but not all infected individuals show symptoms. These symptoms include fever, body weakness, headache, vomiting, pain in joints and limbs, and stiffness. This stage lasts for 2-10 days, and recovery occurs almost immediately in the majority of cases
3. Disease progression to paralysis occurs in a few cases. Here, the polio virus attacks the central nervous system (CNS), leading to paralysis in the limbs and muscles of the respiratory tract. 5-10% of affected children who become paralyzed die because the muscles around their respiratory tract become rigid, causing difficulty in breathing

Paralytic polio 

Paralytic polio happens when the poliovirus attacks the CNS, causing paralysis. The mechanism by which the polio virus invades the CNS is grouped into 4 stages.

• Initial infection and viremia: Paralytic polio begins with the ingestion of the virus and then replicates in the gastrointestinal tract. After the virus has replicated, it then enters the bloodstream, causing viremia. In most cases, this phase may be asymptomatic or present as mild flu-like symptoms⁵
• Secondary viremia: this phase follows immediately after the initial infection. Here, the virus replicates further, this stage increases the chances of the virus getting into the CNS. Although only about 5% of infected individuals develop CNS involvement during this second phase^5,6
• CNS entry: This stage involves the invasion of the virus into the central nervous system. The virus enters the CNS through two routes: by either crossing the blood-brain barrier (BBB) that protects the brain from foreign matter or by traveling through motor neurons in muscles and then moving back toward the spinal cord and brain (Retrograde axonal transport)⁵ 
• Infection of Motor Neurons: Once the virus is in the CNS, it aims for the alpha motor neurons and replicates within these neurons, therefore causing cell death⁶

Effects on physical development

Muscle atrophy

Poliovirus causes infection in the motor neurons, causing cell death, which may lead to complete muscle weakness, mostly in the legs. When these muscles are not used because of the resulting paralysis, they shrink and weaken over time.⁴

Impaired mobility

Children who have suffered from polio disease face challenges with movement, such as struggling with walking, standing, or even sitting upright as a result of affected muscles. This impairment in movement may prevent them from actively participating in everyday tasks and interactions.^7,8

Postural deformities

It is already known that the polio virus affects the muscles, the aftermath of this effect is a resulting muscle imbalance leading to joint deformities, which is not limited to scoliosis and hip dislocation. These children will need interventions to support their mobility and to better adapt to their physical limitations.⁷

Long-term effects

The long-term effects of polio disease include post-polio syndrome and psychological impact. Post-polio syndrome occurs after recovery from the disease and is characterized by muscle weakness, fatigue, and pain. This syndrome can affect physical development and mobility in their transition into adulthood. Polio disease leaves a psychosocial impact on survivors, which is seen in the child’s self-esteem, mental health, and social interactions. 

Therapeutic interventions

The therapeutic interventions for polio focus on rehabilitation, management of symptoms, and preventing complications. Here’s an overview of the key approaches:

Physiotherapy

 Physiotherapy is a necessary treatment option for survivors of polio disease, It is a tailored exercise designed by a health expert or physiotherapist to improve and strengthen the muscles. Although it is an exercise program, it is not strenuous. The focus is on improving both active and passive movements, strengthening muscles, and promoting flexibility. Other forms of exercises designed for these children are: water-based exercises that help enhance general fitness, balance, and strength without stressing weakened muscles and breathing exercises that are done using devices like spirometers to improve respiratory function, especially in patients with bulbar involvement (when poliovirus affects the bulbar region of the brainstem).^9,10

Assistive devices

Children who have suffered from polio may need assistive devices to aid their mobility. These devices can be orthotic devices to help correct deformities and to support weak limbs. An example is a knee-ankle-foot orthosis and a mobility aid such as crutches, walkers, or wheelchairs that those with significant weakness can use to enhance mobility and establish independence.⁹  

Surgical interventions

Surgery is a feasible option and should be considered. Surgical operations are corrective to repair and correct muscle imbalances and possible deformities. These interventions include tendon transfer, joint contracture release, orthopedic procedures, and other techniques employed to stabilize and rehabilitate limbs affected by polio-related deformities.⁶ 

Medication management

Although there is no antiviral treatment for polio disease, medications may be used to manage symptoms such as pain or muscle spasms. There are available vaccines taken to prevent polio disease.⁶

Psychosocial impact of mobility challenges

The psychosocial impact of mobility challenges in polio survivors is profound and multifaceted, affecting various aspects of their lives. Here’s an overview of these impacts:

Reduced quality of life

Polio survivors often experience a significant decline in quality of life, particularly in mobility, daily activities, and emotional well-being. Studies have shown that individuals with post-polio syndrome (PPS) report higher levels of pain, fatigue, and anxiety, which can exacerbate feelings of isolation and depression.¹¹

social isolation

Mobility challenges can lead to decreased participation in social activities. Many survivors find it difficult to engage in outings with friends or family due to physical limitations, leading to feelings of loneliness and exclusion. The inability to attend social events can create a cycle of withdrawal, further impacting mental health and self-esteem.^12,13

Emotional distress

The psychological burden of living with mobility challenges can manifest as frustration, disappointment, and anxiety. Survivors often have to confront the reality of their physical limitations, which may trigger memories of their initial polio experiences. This emotional distress can hinder coping mechanisms and affect overall mental health.^12,13

Impact on independence

Movement limitations often result in dependence on caregivers or assistive devices, which can affect a survivor’s sense of independence. The availability of custom mobility aids like wheelchairs can be beneficial, allowing individuals to navigate their environments more freely and participate more fully in community life.⁸ However, the lack of access to such aids can increase dependence and limit opportunities for personal growth.

Educational and employment opportunities

Mobility challenges can affect access to education and social interactions essential for development. In many regions, a significant percentage of children with disabilities lack access to education due to mobility issues.⁸ 

Summary

The acute phase of polio is marked by a rapid onset of symptoms that can lead to severe neurological damage and paralysis. Understanding this phase is essential for early diagnosis and intervention, which can significantly influence outcomes for those affected by the disease.

The invasion of the CNS by poliovirus is a complex process involving initial infection in the gastrointestinal tract, viremia, and subsequent entry into neural tissues either by crossing protective barriers or traveling along nerves. This invasion results in significant neurological damage and paralysis, highlighting the importance of vaccination in preventing poliovirus infection and its severe consequences

Polio's effects on physical development are profound and multifaceted, influencing muscle strength, mobility, posture, and overall quality of life for affected children. Addressing these challenges through rehabilitation and supportive interventions is vital for helping survivors achieve their potential.