Smallpox. To the veteran or some aid workers, it means a shot and a scar on the upper arm. To some older folks, it is one of many things that was spoken of and discussed in medical circles years ago, but no longer. To the average person it is an ancient ailment that, like many ancient ailments, killed countless, faceless ancestors. It was yet another one of the many things that would take people’s’ lives back then, thankfully long gone now.

However, while smallpox is taken very seriously by those old enough to remember it, and those in medical circles, it is often underplayed by the public at large. The virus was so deadly that it undoubtedly changed the entire course of human history on more than one occasion. Sometimes the sheer numbers of lives that it took are not completely conveyed — in the 1900s alone, it killed an estimated 300 to 500 million people. Many argue that its eradication is one of the greatest medical victories in our history. Another could argue that the threat still exists.

Smallpox was declared eradicated in 1980.

Read the signs and symptoms of smallpox here.

The earliest cases of smallpox date back to ancient days — thousands of years ago, in ancient India, Egypt and China, there are reports that describe something very similar to smallpox. It spread throughout the world under different  names, and it was relentless. Over the course of two years in the 700s, it allegedly wiped out one-third of Japan’s entire population, though it didn’t spread to western Asia and Europe until much later.

These early cases are often disputed, as proof is obviously lacking when it comes to ancient medicine. This disease was so deadly, that a sure way of knowing whether or not it had spread to a country at any given date in history is to see whether or not the historians mentioned it. Many are certain that, if smallpox had spread to their country, they would undoubtedly write about it in great length, as the devastation would be unforgettable.

One notable and infamous spread of the disease was to the Americas during westward European expansion. The sheer numbers of dead Native Americans from the smallpox virus is still not entirely grasped by many Americans today. Think of all the stories of battles between Native Americans and pioneers and settlers — the close calls, the overrun settlements on both sides, the incredible fight that many natives put up.

Now realize that, just prior to all of these battles and wars, smallpox had wiped out 90% of the population; a lot of it occurred so fast, that it outpaced the first contact in many cases. Entire swaths of people were getting wiped out and they hadn’t even seen or heard of a European at that point. The world of the those native to the Americas at the time would be easily post-apocalyptic by any standard, including the Aztec and especially the Incan populations. Smallpox actually incidentally (or intentionally) assisted the colonial efforts of Europe quite often, and not just in the Americas.

Smallpox had similar effects in Australia. In the late 1700s it wiped out nearly half of the aboriginal population upon its arrival. While it did not originate in the country (again, why it was so deadly), many still debate over the method of its transmission from the Asian and European continents to mainland Australia.

Like other diseases, it did not discriminate. It killed countless people — including kings, queens, czars and emperors. It would kill an average 400,000 people throughout Europe every year in the 1700s and 1800s. In the same era, an average of one out of every seventh Russian child would die from the disease. Some estimates say that 4.7 million people died in India in the latter half of the 1800s.

Needless to say — whether it was ancient Japan, Europe or a history of western expansion into the Americas — it is impossible to accurately describe a world that wasn’t ravaged by smallpox. It would be an entirely different world than we have today.

And these are just a fraction of the numerous examples of the unfathomable effects smallpox had civilizations throughout history. According to the World Health Organization (WHO), “Smallpox was a devastating disease. On average, 3 out of every 10 people who got it died. Those who survived were usually left with scars, which were sometimes severe.” In many cases, survivors turned out blind as well.

Eradication

An English doctor by the name of Edward Jenner had made some observations regarding his milkmaids who contracted cowpox, and their resistance to smallpox. He would go on to create the basis for all vaccines, publishing his work, “On the Origin of the Vaccine Inoculation” in 1801. There, he expressed his wishes to develop “the annihilation of the smallpox,” and that “the most dreadful scourge of the human species, must be the final result of this practice.”

From there, the next step was organized efforts to eradicate the disease entirely from the face of the earth. In the late 1950s, WHO began a program focused on just that. 20 years later, the last known fatality was documented in England — a medical photographer who worked just above a smallpox research facility in the Birmingham University Medical School.

The CDC says that the “Eradication of smallpox is considered the biggest achievement in international public health.”

A WHO map on the successful eradication efforts in the late 19th century. Note: Variola major and Variola minor are the two smallpox virus variants.

The mass majority of smallpox stockpiles that were used for research were destroyed after WHO declared the world free from the disease. The only two samples that are officially held are in the hands of the U.S. CDC and the State Research Center of Virology in Russia.

There is some concern over a group or person developing a smallpox virus to use against civilian populations. Since the eradication of smallpox, most health organizations and government programs allocate their resources to combating diseases that we see today. This means that smallpox vaccine production has plummeted, and, for example, most Americans are not vaccinated. Many adults over the age of 40 and service members have the vaccine, but a growing number of the population is vulnerable should someone intentionally release the virus.

Still, there are systems in place to combat the spread of smallpox should it arise again. Health organizations around the world would work tirelessly (as epidemics like smallpox know no boundaries) to contain the virus and treat the patients — starting with containing and vaccinating all known contacts of the infected. They would use many of the same methodologies that found wild success in the 70s.

Featured image: Dr. Walter X. Lehmann, left, and Dr. Kurt L. Brunsfeld, right, vaccinate two unidentifed women for smallpox April 14,1947, as others await their turn in New York City Health Department building. Crowds turned out after Health Commissioner Israel Weinstein’s radio plea that the public be vaccinated. His plea came after nine cases, incuding two fatalities, were reported. (AP Photo/Tony Camerano)