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Today, in many countries, polio can seem to be a disease to which little attention is paid. This is especially true among younger generations, who might view it as a thing of the past. But if you ask their grandparents, or people aged 70 years or older, they may well have relatives and acquaintances who suffered from polio, or may have contracted the disease themselves. This is because it was very common around the world until the second half of the 20th century. It is thanks to vaccination that polio is only found in endemic form in a handful of countries today. That said, isolated cases have appeared a little more widely in recent years.
In Sweden, no domestic case has been registered since 1977. Europe was declared polio-free in 2002, a status South and North America achieved in 1994. However, since September 2024, authorities in five European countries have detected poliovirus in wastewater. As a consequence, the European Centre for Disease Prevention and Control (ECDC) is now calling for measures to be taken. Until polio is eradicated, all children worldwide will need to be vaccinated. But, just as the future of this disease is once again in the spotlight, so too questions are being asked about its past.
A dangerous disease
Polio is an infection, a viral disease that is mainly spread via contaminated water, although it can also be passed on by close contact between people. Three subtypes of the poliovirus are known to have existed. While Type 2 and Type 3 have been eradicated following extensive vaccination programmes, Type 1 is still present.
Around 95% of individuals infected with poliovirus will display no outward signs of the disease. Others will only experience flu-like symptoms: fever, headache, nausea, and vomiting. In many cases, the disease stops at this stage. If the course of the disease is not interrupted, though, after three or four days the virus will enter the bloodstream and reach bodily organs. After this, a range of serious outcomes can occur, including paralysis of the arms, legs, and respiratory muscles, and even death. About one in 200 people infected by the virus will suffer from paralysis, which often affects some parts of the body, rather than all of it. Sadly, children are particularly susceptible to polio.
For reasons that remain unclear, the disease tends to be most prevalent during the autumn months. When poliovirus has manifested in populations where hygienic conditions were poor – a situation that is frequently associated with the Middle Ages – children would often be exposed to the disease during the first year of their life. Antibodies from their mother would, though, suppress the spread of the virus from the infected gut to other parts of the body. Thanks to this protection, while occasional cases of paralysis could occur, they were not common.
It was during the 19th century that polio became far more prevalent and visible as a disease. This occurred against a backdrop of striking demographic change, which saw the human population nearly quadruple over 200 years, between 1750 and 1950, alongside a marked growth in urban living. Compared to the Middle Ages, this was also a period of increasingly hygienic conditions and rising living standards for many – a marked difference from the circumstances usually associated with epidemics becoming more common. Indeed, despite having comparatively good levels of sanitation, Scandinavia was one of the first areas to experience epidemics of polio, with Sweden very heavily affected. There, epidemics recurred again and again between 1881 and 1965. It was only after vaccination began in 1957 that the incidence of polio was drastically reduced.
As we will see, there are grounds to believe that polio has been afflicting humanity for thousands of years, but it is not until the 18th century that definite descriptions of the disease can be found. One example concerns the famous writer Sir Walter Scott, who was born in 1771. At the age of one and a half, he suffered paralysis in the leg after contracting polio, and was left with impaired movement. In the decades that followed, Michael Underwood became the first person to give a clinical description of polio in 1789, while the Italian surgeon Giovanni Battista Monteggia provided the first clear medical description of the disease in 1813. It was a little over two decades later, in 1835, that John Badham documented four cases of polio in Nottinghamshire, Britain, during what may well have been the first epidemic outbreak of the virus in the world.
Tracing incidences of polio before these 18th- and 19th-century outbreaks remains fraught with uncertainty. Even so, a candidate for the oldest indication of the disease is provided by an ancient Egyptian stele dating to 1403-1365 BC, which depicts a man called Roma. He is shown standing with the help of a crutch, because one leg is much thinner and shorter than the other. This leg also has a foot that points downwards, with just the toes touching the ground, which can be caused by a form of paralysis that is consistent with polio. A thousand years later, in around 400 BC, examples of feet displaying comparable traits were noted by the ancient Greek physician Hippocrates. The Roman physician Galen, who practised in the 2nd and 3rd centuries AD, describes isolated cases of paralysis, too, which may have been caused by polio.
A challenging diagnosis
Despite the prevalence of polio in recent centuries, and intermittent occurrences of possible examples in the ancient sculptural and literary records, traces of the disease are seldom identified in skeletal material, regardless of the time period in question. This raises questions about whether polio was simply absent from these populations, or sufferers were buried elsewhere, or if the disease is one that is difficult to identify correctly in the archaeological/palaeopathological record.
This last possibility is supported by a discovery in 1995, at the Dominican Convent Cemetery in Åhus, Sweden. It concerns the skeleton of a child aged between 9 and 12, who was suffering from an affliction that initially seemed impossible to diagnose. This was because his or her leg bones (that is, the femurs, tibias, and fibulas) were slighter than would be expected, but while the shin bones (tibias) were straight, the calf bones (fibulas) were bent. Most conditions, such as rickets, would result in both bones becoming curved. At the same time, the changes to the calf bones were symmetrical, with both the right and left legs affected, making it virtually impossible that they could be caused by healed fractures. An intensive search for disease diagnoses was conducted, with experts in the field consulted around the world. As a result, some very rare disorders were considered, but these were always proposed with reservations, because in all cases the tibia should also have been affected.
It was only when another case was discovered 500km north of Åhus, in the cemetery of a Franciscan monastery and hospital at Linköping, that the picture became clearer. On this occasion, the attention of the specialists was drawn to not only the bent calf bones, but also the appearance of the deceased child’s entire lower limbs and their position within the grave. Instead of lying with his or her legs straight like everyone else who was buried in this cemetery, the left leg was bent at both the hip and knee, leaving it resting on the right leg. At the same time, the left foot was pointing downwards, as if the individual only had his or her toes on the ground. An additional factor was that, just like the first individual, the child’s leg bones were much thinner than would be expected of people who were the same size.
Considering the gracile nature of this child’s legs brought another case to light, involving another child who had probably died at a similar age. This individual had been buried in Hagby Church, which lies in a small village near Kalmar in southern Sweden. This child’s burial had previously been disturbed, leaving the skeleton not only incomplete, but also mixed in with other bones. On this occasion, the leg bones were even thinner – with those on one side smaller than the other – perhaps indicating that this individual had suffered from severe paralysis. It was this possibility that prompted the suspicion that the cause could be polio. Although X-ray images showing the skeletons of individuals affected by polio paralysis are rare, a skeleton in an anatomical collection at the Pathological Museum in Vienna has femurs that are bent, while the tibias remain straight. Despite this similarity to the leg bones from Sweden, it should be noted that other causes remain possible – one that has been considered is a serious condition known as Guillain-Barré syndrome, which can affect children.
Medieval polio?
All three of the children described here died between 9 and 12 years old, but in no case is their sex known. The child from Åhus was buried during the medieval period (AD 1200-1536), while radiocarbon dating of the child from Linköping indicates that he or she died AD 1440-1640. Due to the disturbance of the grave from Hagby, it is more difficult to date the burial, but it certainly occurred before AD 1800, although not earlier than AD 1200.
Based on what is known about the virus, it was probably very common at these times. Even so, serious cases are likely to have been unusual, because most people would have been protected by the antibodies from their mother. As a result, cases of paralysis seem likely to have been rare. Perhaps it is examples of the unfortunate individuals who contracted such occasional cases that have been found here.
Polio became epidemic… against the backdrop of improving living conditions.
Given that polio first became epidemic at the end of the 19th century, against the backdrop of improving living conditions, it is notable that two of these children were buried in cemeteries associated with better-off members of medieval society. Although we can only speculate, it is conceivable that they had lived in more protected environments, and so had only contracted the disease later on in childhood, when they were able to move around by themselves. Alternatively, could the higher status of the household have increased the chance of the children becoming infected, without the mother being affected, meaning she did not have antibodies to pass on?
Whatever the truth, we can conclude from the skeletal changes that for several years – perhaps even most of their short lives – these three children would have had enormous difficulty getting around without help. In the case of the child from Linköping, it is apparent that his or her arm bones weigh considerably more than the respective tibia and fibula combined. This is especially true on the left side, which could indicate that the child used some form of crutches for support. The child from Hagby must also have had considerable difficulty walking, as the leg bones indicate an almost total absence of developed muscles.
All of this raises questions about how children with comparable conditions coped with life in the medieval period. They must have been heavily dependent on the assistance of adults or older children for activities as everyday as going to the bathroom. Even with such help, life was probably much more sedentary than it was for their peers. Study of several thousand well-preserved skeletons from the Middle Ages shows that it is rare to identify children who suffered injuries or illnesses that resulted in a disability during this era. Perhaps this is one of the reasons why adults with disabilities are more often described and discussed in studies of past societies. These three cases present a poignant glimpse of the day-to-day realities for children with physical impairments in medieval societies.
If these children did contract polio, then their circumstances remain highly relevant today, as sufferers of a disease that still exists, despite the potential for its eradication.
All Images: courtesy of Caroline Arcini and Emma Karlsson, unless otherwise stated