Brian MacMahon, who served as chair of epidemiology at the Harvard School of Public Health for 31 years, died last Wednesday. He was 84.

MacMahon’s colleagues described him as one of the most influential men in modern epidemiology. James H. Ware, the current academic dean of the School of Public Health, said that MacMahon’s 1960 textbook was for many years “the bible for young epidemiologists.”

Colleagues credited MacMahon with moving the focus of the Department of Epidemiology away from infectious diseases and toward chronic illnesses, such as cancer and diabetes.

Much of MacMahon’s own research focused on the causes of breast cancer. During his tenure, he received accolades from the American Cancer Society and the American Public Health Association for his work in the field.

Friends and colleagues remembered MacMahon yesterday not only for his contributions to epidemiology, but also for his gentle spirit and character.

Ware said he looked up to MacMahon.

“He was a man of great personal dignity,” Ware said. “He had that British reserve. I thought of him as a role model as to what a professor at Harvard should be like.”

MacMahon’s son Michael recalled how important education was to his father.

“Pops was a family man first,” he said. “He tried to get us all into medicine to begin with, but in the end he thought that education was extremely important no matter what direction you went with it.”

In addition to being a scientist, MacMahon was also an accomplished classical pianist. According to his son, he almost forwent his career in medicine to study music.

Born in England, MacMahon attended the University of Birmingham. He served for two years as a ship’s doctor in the Royal Navy before crossing the pond to study in Brooklyn.

He finally settled at Harvard in 1958, when he assumed leadership of the department.

MacMahon retired from academia in 1989, soon after he stepped down as chair of epidemiology.

He died after suffering complications from a stroke.

Dimitrios Trichopoulos, who succeeded MacMahon as head of the epidemiology department, praised MacMahon’s scientific accomplishments, as well as his personal strengths.

“Brian MacMahon was one of the greatest men in contemporary science,” he said, “not only in terms of pure intellect and scientific drive but in terms of integrity and human qualities.”