Donald “D.A.” Henderson, an American epidemiologist who led the international war on smallpox that resulted in its eradication in 1980, the only such vanquishment in history of a human disease and an achievement that was credited with saving tens of millions of lives, died on August 19 at a hospice facility in Towson, Maryland. He was 87.
The cause was complications from a broken hip, said his daughter, Leigh Henderson.
A self-described “disease detective”, Dr. Henderson spent the defining years of his career as an official of the Centers for Disease Control and Prevention (CDC) and the World Health Organisation (WHO). Later, he served as dean of Johns Hopkins University’s school of public health and as a science and bioterrorism adviser in three presidential administrations.
But it was in the fight on smallpox — perhaps the most lethal disease in history and one that killed an estimated 300 million people in the 20th century alone — that he became known around the world. Lent from the CDC to the WHO for a decade in the 1960s and 1970s, he commanded a small cadre of public-health officials and an army of field workers in an endeavour that amounted to a medical moon shot.
“I think it can be fairly said that the smallpox eradication was the single greatest achievement in the history of medicine,” Richard Preston, the bestselling author of volumes including The Hot Zone, about the Ebola virus, and The Demon in the Freezer, about smallpox, said in an interview. He described Henderson as a “Sherman tank of a human being — he simply rolled over bureaucrats who got in his way.”
For millennia, at least since the time of the Egyptian pharaohs, smallpox had ravaged its way around the world. Caused by the variola virus, it was an exceptionally painful and gruesome disease. Victims suffered from fever and other flu-like symptoms before developing a rash of the pustules that gave the disease its nickname: the speckled monster. It killed a third of its victims and left survivors disfigured, sometimes blind.
“Smallpox has been called one of the most loathsome diseases,” Henderson told The Washington Post in 1979. “I know that no matter how many visits I made to smallpox wards filled with seriously ill and dying patients, I always came away shaken.”
Populations had long sought to protect themselves from smallpox through crude methods of inoculation, the process by which a patient is intentionally exposed to a disease to provoke a mild reaction and thereby obtains immunity from a more serious infection.
In the 18th century, an English physician, Edward Jenner, discovered that exposure to the less dangerous cowpox virus produced immunity to smallpox. He is regarded as the father of the smallpox vaccine, which was perfected over the years and severely curtailed the spread of the disease in areas where the vaccine was distributed. Because of large-scale immunisations, the United States was free of smallpox by 1949.
But the disease continued to bedevil countries around the world, particularly in South America, South Asia and Africa. In the late 1950s, the Soviet Union began to apply pressure on the WHO, which is an agency of the United Nations, to mount a campaign to wipe out smallpox.
Many WHO officials were hesitant to embark on such an ambitious operation, fearing that a defeat would erode the organisation’s credibility. Previous efforts to eliminate other diseases such as yellow fever and malaria had “failed spectacularly”, according to Jason Schwartz, a historian of medicine at the Yale School of Public Health.
When it was agreed that the WHO would take on the smallpox initiative, the organisation turned to the US, which, under Henderson’s leadership, had already launched a smallpox-eradication programme in Africa. In an oral history with the online Global Health Chronicles, Henderson recalled that the WHO director general, the Brazilian malariologist Marcelino Candau, called the US surgeon general with a demand.
“I want an American to run the programme,” Candau said, “because when it goes down, when it fails, I want it to be seen that there is an American there and the US is really responsible for this dreadful thing that you have launched the World Health Organisation into, and the person I want is Henderson.”
Pressed by the surgeon general, and apprehensive about his chances of success, Henderson arrived in Geneva in 1966. For the next 11 years, he shuttled between Geneva and far-flung smallpox hot spots — obtaining funding, coordinating with nations including the Soviet Union amid Cold War tensions, and inspiring heroics from the tens of thousands of field workers who ventured into countries racked by deprivation, natural disaster, political instability and war.
The campaign, which cost an estimated total of $300 million (Dh1.1 billion), employed a strategy called ring vaccination that was credited to the American epidemiologist William Foege. Rather than attempting to vaccinate everyone — a technique determined to be superfluous — the WHO located smallpox patients, isolated them, vaccinated everyone who had contact with the victims, and then vaccinated everyone who had contact with those people.
