It has been 40 years since the World Health Organization (WHO) announced the eradication of a disease that killed hundreds of millions of people in the 20th century alone, and apparently destroyed entire civilizations in the new world.

“I am the luckiest man on earth. I got to see the last case of smallpox in the world.”
An epidemiologist who took part in the eradication of smallpox

 For thousands of years, smallpox terrified humanity. There are documented cases of fatalities caused by the disease from more than 3,000 years ago, including Ramses the Fifth, King of Egypt. However, new studies show the virus in its present form is a few hundred years old.

The smallpox virus enters the body through inhalation and incubates for 7-17 days. During this period, it infects cells in the respiratory system and lymph nodes. Two weeks after infection, the infected cells begin to disintegrate and the viruses are released into the blood system, infecting organs such as the spleen, lymph nodes, and bone marrow.

At this stage, flu-like symptoms, such as fever and muscle pain, appear. They are followed by nausea, vomiting, and back pain. Then the virus begins to attack skin cells and several days later, distinctive blisters appear all over the body. 70-75% of the patients will be lucky, and the disease will only lead to scarring. The rest will die from an overreaction of the immune system, dehydration, or multiple organ dysfunctions, and that’s without mentioning the more violent viral strains.

Smallpox killed 300-500 million people in the 20th century alone, and some believe it caused the downfall of the Aztec, Inca, and other civilizations during the colonial conquests of North and South America. It is, indeed, one of the deadliest diseases in history.

Watch this video of the Science Photo Library about the life cycle of the smallpox virus:

Vaccine invention

Exposure to the smallpox, or similar, virus as a preventive treatment is not new. There are accounts of vaccine-like treatments from the 10th century China, where they took the fluid secreted from the blisters in infected people during the recovery stage and used it to infect other people. These kinds of treatments existed throughout history in various cultures, but only at the end of the 18th century were they tested in an experiment that would probably not be approved today, for ethical reasons. In 1796, British doctor Edward Jenner infected James Phipps, his gardener’s son, with cowpox – a bovine disease, exposure to which Jenner had suspected to confer immunity to smallpox. Two months later, he infected the child with smallpox, and to everyone’s delight, the child did not fall ill. Initially, the scientific community reacted to the new and strange treatment with ridicule and doubt, but over the years, evidence accumulated of the treatment’s efficacy, and it was further validated by Louis Pasteur’s studies focusing on a vaccine for rabies. It was the opening shot in the journey of eradicating smallpox. Over the next 200 years, the vaccines improved and spread around the world as preventive treatment. Jenner’s work was memorialized in a medical term: The word “vaccine” originates in the Latin word for cow – vacca.

At first, the vaccine was produced by collecting fluid from blisters in children who were vaccinated against cowpox and then administering it on scratches in the skin of children who were not vaccinated yet. Obviously, without washing the blade with which the cuts were made. It was a primitive vaccine with a high risk of infections that sometimes led to death, and parents had to make the impossible choice, between the risk of their child’s becoming infected with the lethal disease and the risk that he or she might die of a fatal wound infection. At the beginning of the 20th century, with the rise in hygiene awareness, the number of infections dropped and concurrently, more effective vaccines were developed.

In the early 1950s, Smallpox was eradicated from Europe and North America. In 1959, there were discussions about a worldwide vaccination offensive to eliminate the disease that was still prevalent in South America, Asia, and Africa. It was feasible because the virus only attacks humans; if a point was reached in which there were no sick people or disease carriers and the vaccination rate was sufficiently high in the population, the virus would not be able to spread. Unfortunately, it was not realized, mainly due to lack of funding.

לשחרר את העולם מהמחלה המידבקת הקטלנית ביותר במדינות רבות. ההצהרה על הדברת האבעבועות השחורות
Freeing the world from the lethal infectious disease. An announcement on Smallpox.

The last patients

In 1966, the World Health Assembly allocated funding specifically to eradicating smallpox, thus launching one of the most ambitious health projects in history. In just a few years, smallpox infection rates plummeted. The idea was simple: Diagnose the disease by the usual symptoms and inoculate everyone in the patient’s environment, in order to prevent further infection. The project’s participants went from village to village with pictures of sick children and located patients and carriers of the disease.

In 1975, the last carrier of the most deadly strain of the disease (Variola major) was identified – Rahima Banu, a three year old from a small village in Bangladesh. She was kept in isolation until she passed the infectious stage. Simultaneously, all the people in a 2.5 km radius from her home were vaccinated. Two years later, a cook in a hospital in Somalia, Ali Maow Maalin, was identified as the last carrier of the less lethal strain of the disease (Variola minor). In 1978, the disease killed its last victim, Janet Parker, a medical photographer at the University of Birmingham, who worked one floor above a microbiology lab. She was apparently infected by a lab strain that was present in the hospital’s ventilation system or during one of her visits to the lab.

On May 8, 1980, almost 200 years after Jenner’s experiments, the WHO declared smallpox eradicated. “Having considered the development and results of the global program on Smallpox eradication initiated by the WHO in 1958 and intensified since 1967 … Declares solemnly that the world and its peoples have won freedom from Smallpox, which was a most devastating disease sweeping in epidemic form through many countries since the earliest times, leaving death, blindness and disfigurement in its wake and which only a decade ago was rampant in Africa, Asia and South America.”

Samples of the smallpox virus are still kept in labs in the U.S. and Russia, for research purposes, despite health organizations’ suggestions of destroying them. There may also be a few more countries that have such samples without WHO consent. Some countries hold a large stock of vaccines if the disease breaks out again, even though the probability of a natural outbreak is zero.

Today, there are a few other diseases that global health organizations are focused on, like polio and measles. Hopefully, in a few years’ time, they too will become a distant memory of a disease that can no longer harm us.