health & science

Smallpox: a disease in deep freeze

In the first of an ongoing series on vaccines, Farah Hancock takes a look back at the first vaccine created and the only human disease to be eradicated

A cow called Blossom is the unlikely hero in the fight against a disease estimated to have killed between 300 and 500 million people.

Smallpox is now eradicated, with the last recorded case in the 1970s. The keys to its eradication were milkmaids, cows and the development of the world’s first vaccine.

University of Waikato’s senior lecturer in biological sciences Alison Campbell said the disease would start with symptoms similar to a flu.

“You would get a really high fever, you would get headaches, you would feel like crap. Your joints would hurt. Then you would get a rash which would start off on your head and spread over your body. It started as a red rash, then it went into bumps and the bumps turned into these pussy blisters.

“Then the blisters burst, and you were open to secondary infections from these open wounds. Once they scabbed off you normally recovered. That’s some small comfort.”

There were four types of the smallpox disease. Overall the fatality rate was 30 percent but for haemorrhagic smallpox the death rate was nearly 100 percent. Spread through particles in the air, contact with infected material, and sometimes even bedding, smallpox infected both adults and children.

A Bangladeshi girl with smallpox, 1973. 

Smallpox is one of many diseases for which vaccines have been developed. With vaccination rates falling, there’s concern among health professionals that people have forgotten the severity of some of the diseases vaccines prevent.

Unless smallpox escapes from the laboratories which hold small samples of the virus, or somehow re-emerges as a result of climate change, there’s little chance it will re-establish itself. However, many other serious vaccine-preventable diseases still occur naturally in the world.

“2000 came down with it, mostly Māori and there were 55 deaths, also mostly Māori.”

The World Health Organisation (WHO) recently listed “vaccine hesitancy” as one of 2019’s top 10 threats to global health and notes there has been a 30 percent increase in measles. It worries that a hesitancy to vaccinate threatens to reverse progress made tackling vaccine-preventable diseases.

Another threat on the WHO’s top 10 list is antimicrobial resistance. Their website says: “Antimicrobial resistance – the ability of bacteria, parasites, viruses and fungi to resist these medicines – threatens to send us back to a time when we were unable to easily treat infections such as pneumonia, tuberculosis, gonorrhoea, and salmonellosis.”

In some cases, vaccines preventing diseases such as tuberculosis and possibly gonorrhoea could be a saving grace when antibiotics become ineffective.

Smallpox in New Zealand

Despite being separated from other countries by long sea voyages, New Zealand was not spared the disease. It killed far fewer people than influenza, but its arrival was met with strict controls in an attempt to contain it.

“The worst outbreak we had was in Northland in 1913. Apparently, a missionary coming over from the United States picked it up on a ship while he was getting out here. He went to a hui in April and spread it around,” said Campbell

“Two thousand came down with it, mostly Māori, and there were 55 deaths, also mostly Māori."

The disease was controlled through quarantine, travel restrictions and a mass vaccination programme.

“Interestingly the article I read said Māori were far more willing to be vaccinated than Pākehā were.”

Part of the willingness may have been due to public health measures. In order to travel by train during the outbreak, Māori people were required to present a certificate to prove they had been vaccinated.

A certificate Māori passengers needed to present in order to travel on trains during the 1913 smallpox outbreak. Photo: CC BY 3.0

Preventing the ‘pox

The path to the vaccine was winding. Initially variolation was used. The term came from the name of the smallpox virus, variola. The practice has been documented in China, Turkey and Africa. In China there’s evidence of variolation occurring in the 15th century, with a description that scabs were powdered and blown up the nose of a healthy person.

Campbell said other countries relied on breaking the skin.

“Some old lady usually, they tended to be the one nursing the sick people, would collect some pus from someone’s open blisters. They would go to someone who wanted to have the variolation treatment done, and they would scratch their skin until it bled with a needle, and then put some pus into the wound.

“Sometimes you got full-blown smallpox and died.”

Often though, people would get a mild form of the disease, recover and develop immunity to the virus.

The method was introduced to the western world by English aristocrat Lady Mary Montagu. She survived smallpox as a child but had lost other family members to the disease. While living in Turkey she learnt of variolation and in 1718 had her five-year-old son successfully variolated.

This was overseen by an English doctor who decided to test the method on a larger scale. A trial was conducted on condemned prisoners who Campbell said were given a deal “better than hanging”.

“If you survive, we’ll let you go. They all survived and presumably he let them go.”

This began the widespread acceptance of the method. However, the risk of death remained. Another serious issue was the number of variolated people spreading the disease to others while they were contagious.

A case of smallpox, 1886.

Blossom, the milkmaid and the gardener’s son

At the close of the 18th Century, English physician and scientist Edward Jenner realised milkmaids seldom got smallpox. He postulated that the immunity could be due to their exposure to cowpox. Milkmaids were often exposed to cowpox by touching infected cows’ udders. Cowpox does affect humans but is far less severe than smallpox.

He tested his theory on his gardener’s eight-year-old son. A cow called Blossom had infected a milkmaid with cowpox. Blisters from the milkmaid’s hand were scraped and the pus spread on the boy’s scratched arms. Six weeks later he exposed the boy to smallpox.

“The boy didn’t get it. These days this would be unethical, but back in the day that was the way people worked.”

Subsequent tests had the same result and vaccination replaced variolation as a method which had the advantage of not killing the recipient and not causing the spread of the smallpox virus.

“The other fear was somebody other than the US and Russia might have a supply and they might release it as a bio-terrorism act.”

By the late 1800s a standardised vaccine was created and the last naturally occurring instance of the disease was recorded in Somalia in 1977. Another death in 1978 happened when a laboratory-stored virus caused the death of a medical photographer.

Smallpox under lock and key

The disease is eradicated in the wild but is still kept in two approved laboratories in the United States and Russia. In 1986 the WHO recommended all stocks of the virus should be destroyed. There was opposition to this.

“The official reason [to keep the virus] is to develop better vaccines and better treatments. They have actually come up with a better vaccine than the one which was in operation," Campbell said. 

“The other fear was somebody other than the US and Russia might have a supply and they might release it as a bio-terrorism act.”

This fear was so great 450,000 US military personal were vaccinated after 9/11.

Instances of the virus have been found outside of the sanctioned laboratories. In 2013 cloned fragments of the virus were found in a South African laboratory.

In 2014, vials from the 1950s containing live samples of smallpox were discovered in an old cardboard box in an unused part of a storeroom of the National Institute of Health in the US.

In both instances the virus was destroyed under the supervision of the WHO. The question over the destruction of the remaining samples held in the approved laboratory deep freeze remains open.

Zombie anthrax 

There’s a small chance the virus may resurface in the wild as climate change melts ice.

In Siberia, melting permafrost is uncovering infected corpses. "Zombie" anthrax, caught from spores in long-dead reindeer, infected 24 people and led to a mass cull of reindeer in the region in case they had contracted it. Since then scientists have looked for for signs of smallpox in frozen corpses found in the area.

Corpses were found with sores resembling those caused by the virus, and fragments of the virus’s DNA have been found in one body believed date to the 1700s. The virus is known to remain viable for more than a decade in saved scabs in a temperate climate, so there’s a possibility more than just fragments may eventually be found in places where extreme cold has preserved them.

Whether the virus could be revived and become infectious is another question. Two “giant” viruses (a type of virus so large they can be seen under a normal microscope) have been found after 30,000 years under the Siberian permafrost. Posing no threat to humans as they only infect single-celled organisms, these viruses, once revived, quickly became infectious.

Scientists, cautious as always, now rate the chance a microbe could be revived and infect humans as a non-zero probability.

In the event of a non-zero probability chance the virus escapes from a frozen tomb, a laboratory, or be used as a weapon, the effect on a population which hasn’t vaccinated for decades could be devastating.

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