American epidemiologist Donald Ainslie Henderson — leader of the international campaign against smallpox in the 1980s — has passed away at age 87. According to his daughter, Leigh Henderson, D.A. died Aug. 19 at a hospice in Maryland due to complications from a hip fracture.

D.A. will forever be known for his work as a "disease detective," which led to the eradication of smallpox more than 30 years ago. This achievement was the only such vanquishment of a human disease in history, consequently saving millions of lives.

Disease Detective

Henderson had spent years as an official of the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) before joining the Johns Hopkins University's School of Public Health. He served as the dean.

He also became a bioterrorism and science adviser under three presidential administrations in the United States. But it was Henderson's "war" against smallpox that changed the world.

Smallpox is considered as one of the most lethal diseases in history, killing about 300 million people in the 20th century alone. Smallpox is caused by the variola virus and can afflict fever and flulike symptoms to infected patients before they develop a rash of the pustules.

Nicknamed the "speckled monster," the disease has left survivors almost blind or disfigured.

An 18th century English physician named Edward Jenner found that the cowpox virus produced immunity against smallpox. Jenner is known as the father of the smallpox vaccine, which had been perfected over time.

By 1949, the United States was free of smallpox due to large-scale vaccinations. However, the disease continued to ravage countries around the world.

In the 1960s and 1970s, Henderson worked for the WHO on behalf of the CDC, commanding a small group of public health experts and an army of field workers. It was a medical moonshot to eradicate smallpox around the world.

When it was decided that the WHO will take on the smallpox initiative, Henderson had already begun work in Africa.

In the next several years, instead of attempting to vaccinate everyone, the WHO used a strategy known as ring vaccination — credited to American scientist William Foege.

Henderson and countless field workers located patients, isolated them, vaccinated people who had contact with the patients and vaccinated those who had contact with these people.

The campaign was effective because of a vaccine being constituted in a freeze-dried form which could endure high temperatures in tropical areas. The vaccine was administered through the use of a sharp, two-pronged rod that can be used even by non-professionals.

Richard Preston, author of best-selling books about infectious diseases such as the book about smallpox called "The Demon in the Freezer," described Henderson as "Sherman tank of a human being" because he rolled over "bureaucrats" who got in the way.

Eradicate All Samples

Although the smallpox has not wreaked havoc since the 1980s, scientists from the United States and Russia seem to keep stockpiles of the disease. Heavily secured facilities in Siberia and Atlanta hold officially sanctioned stores of the virus.

Years ago, Henderson argued that these samples should be destroyed because he believed that any amount of smallpox was too dangerous to keep.

Preston says that since no one has been exposed to the virus, most of the population would be vulnerable in case of an outbreak.

Henderson said in 2002 that he felt dispirited because the world was regressing to defend against something that was thought to be completely defeated.

"We shouldn't have to be doing this," he had said.