The American epidemiologist whose unwavering leadership resulted in the eradication nearly 40 years ago of smallpox, one of the world’s most feared contagious diseases, has died.

Dr. Donald “D.A.” Henderson was 87 when he died Friday at a hospice care facility in Towson, Maryland, from complications following a hip fracture, Johns Hopkins University said in a statement. Henderson was a former dean of the school’s Bloomberg School of Public Health.

He was most recently employed as a distinguished scholar at the University of Pittsburgh Medical Center’s Center for Health Security in Baltimore.

“D.A. Henderson truly changed the world for the better,” the center’s director, Tom Inglesby, said in a statement.

Henderson was working on smallpox eradication at the U.S. Centers for Disease Control and Prevention in 1966 when the World Health Organization chose him to lead the global eradication effort. In a 1988 interview with the WHO Bulletin, Henderson said he accepted the challenge reluctantly, knowing that he and the United States would be blamed if the project failed.

The battle was essentially won during a 10-year period, 1967-77, by medical workers using a surveillance-and-containment strategy rather than the mass-vaccination approach used in the past. Much like the Ebola containment strategy recently employed in West Africa, the smallpox project focused on cases and outbreaks, progressively eliminating the disease from where it still existed in South America, West and Central Africa, Asia and finally East Africa.

The last naturally occurring case of smallpox was diagnosed in Somalia in 1977. The World Health Assembly declared the deadly disease eradicated in 1980.

Former CDC director Dr. William Foege, 80, who was among the first to apply the surveillance-containment strategy, remembered Henderson as having the vision to plan a campaign he knew would take a decade.

“One of his characteristics was absolute certainty about things, and people like to follow someone that is certain about what they’re doing,” Foege said in a telephone interview.

Dr. Michael Klag, dean of the Bloomberg school at Johns Hopkins, described Henderson in the school’s statement as “a force of nature who, until recently, seemed invulnerable.”

CDC Director Tom Frieden said in an email that Henderson played an instrumental role in smallpox eradication.

“His impressive career contributed to saving millions of lives, and will continue to save lives for generations to come,” he wrote.

Henderson was born Sept. 7, 1928, in Lakewood, Ohio. He is survived by his wife, Nana, daughter Leigh and sons Douglas and David.