It was on Friday, August 11, 1978 when Janet Parker began to feel unwell.
Within days, the 40-year-old medical photographer had developed unsightly red spots on her back, limbs and face.
Soon, she was so weak she couldn't stand without assistance, reports News.com.au.
A month later to the day, on September 11 — now blind in both eyes; in renal failure; and having developed pneumonia — Ms Parker died.
What doctors initially diagnosed as chickenpox was actually smallpox — one of the deadliest and most contagious diseases known to humankind, and thought to have been eradicated less than a year earlier.
After killing over half a billion people in the 20th century alone — three times the number of deaths from all of the century's wars combined — on October 26, 1977 the last natural case of smallpox was discovered in Somalia.
Presenting as flu-like symptoms, the disease then progressed into a rash consisting of deep sores — filled with fluid that would blister, ooze, crust and scab over, and permanently scar the bodies of those lucky enough to survive.
Just one teaspoon of the virus was enough to infect every man, woman and child on earth.
With no cure, and killing a third of those it infected, people tried to combat the disease with treatments that included being bled, purged, starved, and wrapped tightly in red cloth.
When British doctor Edward Jenner created a vaccine against the illness, he arguably saved more lives than anyone else in history. A global vaccination program — led by the World Health Organisation (WHO), was employed to wipe out the disease, and by the 1970s cases were rare.
Today, more than 40 years later, the eradication of the disease is still considered one of the most spectacular successes of a vaccination.
How, then, did the disease — which doctors were about to declare gone for good — return ten months later to claim its final victim?
Had Ms Parker's mother Hilda Witcomb not been sceptical of the doctor's misdiagnosis — having nursed her daughter through chickenpox as a child — the large, blistering pustules appearing on Parker's body may have gone unacknowledged.
After nine days — and showing no signs of improvement — Ms Parker was admitted to the Catherine-de-Barnes Isolation Hospital in Solihull, near Birmingham, England.
"I do remember thinking she was very poorly, she had a very dramatic rash," Professor Deborah Symmons, the first member of medical staff to see Ms Parker when she was admitted, said. "It was widely thought the last case had occurred."
After an initial examination, though, the doctors' worst fears were confirmed: variola — the scientific name for the disease — was back.
Its return prompted the WHO — and the media — to descend on the city, elevating Ms Parker's diagnosis to a worldwide issue.
As medical teams jumped into action, those closest to her were questioned about their recent movements for fear the disease could spread further, and swiftly quarantined and vaccinated.
Everyone who came into contact with Ms Parker from the moment she was hospitalised — from ambulance staff to the hospital chaplain — were treated similarly.
Only two weeks after Ms Parker had first shown symptoms of the disease, more than 500 people had been vaccinated, and while her life slowly ebbed away, one question plagued the hospital's staff: How had she been infected in the first place?
Professor Henry Bedson, who headed the smallpox laboratory at Birmingham Medical School where Ms Parker worked, was joined by consultant in infectious disease Professor Alasdair Geddes to examine Ms Parker's samples.
Prof Bedson was horrified to discover that the particles that had infected Ms Parker had escaped from his own laboratory — likely having reached her through the building's venting — and leaving Prof Bedson so distraught that days later he took his own life.
"I am sorry to have misplaced the trust which so many of my friends and colleagues have placed in me and my work," he wrote in the note he left.
Before Ms Parker succumbed to the disease, the Birmingham outbreak in some ways claimed a third victim when her father Frederick died from an apparent cardiac arrest, thought to have been brought on by the stress of his daughter's illness.
Six days after her father's death, and five after Prof Bedson's — and without the arms of a loved one around her or there to hold her hand — smallpox claimed Ms Parker as its final victim.
An undertaker sent to the isolation hospital found her body lying on the floor of a garage, packed in sawdust, soaked in disinfectant and wrapped in a transparent body bag.
The city was declared free of the disease on October 16, 1978, and in October 1979, Prof Bedson was exonerated, with Birmingham Magistrates' Court dismissing the prosecution's evidence that the university had contravened the Health and Safety at Work Act.
While in 1980 a government-commissioned paper found there was "no doubt" that Ms Parker had been infected at the laboratory, how exactly she contracted the disease still remains unanswered.
At the time, doctors predicted Ms Parker contracted the disease after it travelled through the air, but according to the paper, there were two other routes that the virus could have transferred along: by personal contact or by contact with contaminated equipment or apparatuses.
"Why did she die, why did she get it so badly?" Symmons said in 2018.
"If we couldn't find out what happened 40 years ago, it won't suddenly become clear now."
On December 9, 1979 the Global Commission for the Smallpox Eradication signed their names to the statement that "smallpox has been eradicated from the world".
To date, there have been no further outbreaks of the disease.