Aaron O'Neill
Research lead for society, economy, and politics: Europe & global
Smallpox - Statistics & Facts
Throughout history, smallpox was one of the most devastating and widespread diseases known to humanity, and was responsible for an immeasurable number of fatalities. The earliest recorded cases took place in either Egypt or India over 5,000 years ago. Over the next five millennia, smallpox was endemic to Afro-Eurasia. The 16th century saw Europeans bring virgin soil pandemics to the Americas (i.e. they introduced new diseases to populations who were genetically defenseless), and historians estimate that the indigenous population fell to less than ten percent of its pre-colonization level by the late-1700s, with smallpox as the driving force behind this change.
Contrary to Jenner’s beliefs, vaccination in infancy did not guarantee lifelong protection, and the share of smallpox cases in adults increased. This was first observed in German armies in the 1830s and 1840s, who then revaccinated all recruits upon enlistment. Mandatory revaccination was not required in the French Army, and the Franco-Prussian War led to the outbreak of the last smallpox wave to reach pandemic levels across Europe. This resulted in many countries, such as Germany, Britain and Sweden, introducing stricter and enforced vaccination laws. Iceland recorded its final smallpox case during this pandemic, in 1872, making it the first country to successfully eradicate the disease in nature, and countries on the mainland began recording their final cases around the turn of the twentieth century.
Children the most at-risk
In Europe, where there is much more (bit still limited) data relating to the effects of smallpox, the evidence shows that infants and children were most at risk. In the pre-vaccination era, well over ninety percent of smallpox deaths occurred in those under the age of ten. Cases were rarer in adults, as most had already contracted the disease in their childhood. This generally granted lifelong immunity, although many were left with severe scarring or blindness for the remainder of their lives. Estimates suggest that smallpox was responsible for one third of all adult blindness.Symptoms
Smallpox affected humans only and was transferred through contact with water droplets from coughing or sneezing, or infected surfaces. There was typically an incubation period of 12 to 14 days before the disease would show through influenza-like symptoms. Four days later, a rash would cover the patient's body, resulting in lesions, pustules and scabs. The most common and deadliest strain of the disease was variola major, which had a fatality rate of approximately thirty percent in the pre-vaccination era; in contrast, the variola minor strain had a fatality rate below one percent. Johann Juncker, one of Europe’s leading researchers of smallpox in the 1700s, estimated that five of every six Europeans would contract smallpox at some point in their lifetime, and that it took over 400,000 lives in Europe each year.Discovery and implementation of vaccination
Varying inoculation techniques existed in Asia for almost one millennium, and Turkish variolation practices became commonplace in Western Europe in the 1700s. These involved immunizing patients using mild doses of smallpox. However, results were inconsistent and often developed into severe smallpox cases or even epidemics. In the 1790s, British scientist Edward Jenner noticed that milkmaids developed smallpox immunity while working with cows infected with cowpox. Jenner then inoculated a young boy with cowpox, which induced a mild reaction, was non-contagious, and successfully granted protection from smallpox. Jenner’s studies were initially rejected, as infecting humans with a bovine disease was controversial, but the results proved effective and his work was quickly accepted by the medical community. Despite this acceptance, many countries were often slow to adopt compulsory vaccination, with Britain not making vaccination compulsory until 1852, and France in 1902. Iceland, where one third of the population died in a single smallpox epidemic in 1707, was the first country to introduce compulsory vaccination in 1802. It was joined by several German and Scandinavian states over the next two decades, and by the mid-1800s the smallpox fatality rate fell drastically in these countries, particularly among infants and children (who had been the most susceptible in previous years).Contrary to Jenner’s beliefs, vaccination in infancy did not guarantee lifelong protection, and the share of smallpox cases in adults increased. This was first observed in German armies in the 1830s and 1840s, who then revaccinated all recruits upon enlistment. Mandatory revaccination was not required in the French Army, and the Franco-Prussian War led to the outbreak of the last smallpox wave to reach pandemic levels across Europe. This resulted in many countries, such as Germany, Britain and Sweden, introducing stricter and enforced vaccination laws. Iceland recorded its final smallpox case during this pandemic, in 1872, making it the first country to successfully eradicate the disease in nature, and countries on the mainland began recording their final cases around the turn of the twentieth century.
Eradication
The development level of many non-European or non-Anglophone countries presents difficulties when trying to study the role that smallpox played there. The number of reported cases in African and Asian countries is considered by many to be a small fraction of the actual numbers, though they do present an insight into the patterns and trends of the virus. By the mid-1900s, smallpox had been eradicated across Europe and North America, and the 1970s saw the final reported cases of smallpox across the remaining continents. In 1980, the World Health Organization declared smallpox to be completely eradicated, making it the first human disease to have been eliminated in nature. Recent decades have seen the suppression of several other diseases, such as polio and malaria (both of which are expected to be eradicated globally in the coming years). Smallpox remains the only human disease to have been eradicated, in one of the most significant medical achievements in human history.
