During the 60s and 70s emphasis in medical care was to develop vaccines against the rising number of childhood diseases. One of the diseases that received attention at that time was polio, also known as poliomyelitis or infantile paralysis. Polio is an extremely contagious viral infection that causes damage to the nervous system, which can result in paralysis, breathing difficulties and, in some cases, death. However, not all cases of polio display obvious symptoms. In approximately 95% of cases the infection can mimic the flu, lasting from a few days to a few weeks.
Polio tends to affect children under the age of five and is spread by ingesting food or water that contains human faeces and, in some cases, by infected saliva. The first case was reported in England in 1789 by Michael Underwood, who saw cases of children presenting with weakness and paralysis of the legs. Symptoms seemed to be more common in the summer and autumn, and over the next few hundred years the numbers increased, as did the average age of those infected. By 1952 there were over 21,000 young people in America who displayed symptoms of paralysis.
In 1955 the first vaccine was developed. It involved injecting people with the inactivated (killed) poliovirus. By 1962 an oral version of the vaccine was developed which was easier and cheaper to administer, and so began journey of eradication.
In developed countries polio has virtually been eradicated. No cases have been reported in Latin America and the Caribbean since 1991. Polio is now found only in Nigeria, Pakistan and Afghanistan, and their cases are declining. Between 2014 and 2015 there was a 79% decrease in reported cases globally and in 2017 only 22, indicating total eradication is possible.
Even though it looks likely the disease will be totally eradicated worldwide, polio is not letting us forget that it existed. In the last 20 or so years there have been reports of recurrence of symptoms in people who were diagnosed or suspected of having polio when they were younger. Research has revealed that around 50% of people who had polio as children will go on to develop post poliomyelitis syndrome (PPS).
So what is PPS?
PPS is a condition that affects survivors of polio years after the initial illness. However, not every person who had polio will develop this condition. Unlike polio, PPS is not contagious. Why some people develop symptoms and others don’t, is not fully understood. It is thought that it is the result of neural fatigue—the nerve cells that took over the work of the ones damaged by the polio virus become overworked.
Symptoms are typically observed between 30 and 40 years after recovery and tend to appear in clusters. The first sign is usually gradual weakness in muscles that were not previously affected, or worsening weakness in muscles that were previously affected. The presentation of symptoms varies; some people may experience only minor symptoms while others have severe disabling and debilitating symptoms that can make everyday activities difficult.
The most common symptoms are:
• Muscle weakness that progresses slowly
• Muscle atrophy (reduction in muscle size)
• Difficulties with speech, breathing and swallowing
• Joint pain
• Posture changes such as the late onset of scoliosis
• Sensitivity to cold temperatures
• Poor memory and difficulty concentrating
• Irregular sleeping patterns or sleep apnoea
• Constant tiredness
• Unexplained mood swings and depression
Although the condition itself is not life-threatening, weak respiratory muscles and difficulty swallowing may lead to complications such as breathing problems and pneumonia which can lead to death.
As there are no laboratory or diagnostic tests available for PPS, diagnosis is dependent on ruling out similar pathologies, and the presence of certain criteria which can be determined by taking a thorough medical history and physical examination. The most obvious criteria are a previous diagnosis of polio, the length of time since recovery and the gradual onset of weakness.
At present there is no cure for PPS and treatment focuses on the management of symptoms and interventions to promote independence and improve quality of life. Exercise may be beneficial, by keeping the muscles strong and slowing down the weakness, but activity can also have the opposite effect and leave the muscles feeling fatigued. To overcome this, pacing chores and daily activity is vital to finding the perfect balance. Medication also has an important role to play in controlling joint and muscle pain. Physiotherapy is another useful intervention, not only to give advice and guidance on exercise and pacing activities but also on mobility aids and supports for weakened joints.
With polio almost eradicated worldwide, this problem will disappear but, for now, the take-home message is to be up-to-date with your vaccinations, keep active and stay vigilant.
