A man known as South Africa’s “grandfather” of AIDS, Rueben Sher, died Monday after post-surgery complications, reports Health-e/AllAfrica.com.

Sher was an immunologist who traveled the world and spoke about HIV and AIDS. He became known as one of the first people in the scientific community to tackle the disease. Dr. Francois Venter, president of the HIV Clinicians Society, called Sher “a man who warned us all that HIV would decimate the country, was ignored, and was tragically proved right.”

“He was without a doubt the first person in the scientific and medical community who tackled AIDS head on,” recalls Dr. Des Martin, another AIDS stalwart.

In 1986, Sher and another doctor started a once-a-week AIDS clinic at the Johannesburg General Hospital, which ended up taking the bulk of early AIDS patients in the city.