Dr. Mark Wainberg, a celebrated Canadian scientist known internationally for his ground-breaking research on HIV/AIDS, has died after an incident swimming in southern Florida. He was 71.

CTV News has confirmed that Wainberg was with family in a Miami suburb on Tuesday when he had trouble swimming.

According to the Bal Harbour Police Department, Wainberg’s son noticed that his father was missing and swam into the ocean and brought him back to shore.

“At that point, other beachgoers assisted in bringing the victim onto the beach, which is when we arrived,” Mike De La Rosa, acting captain for the Bal Harbour Police Department, told CTV Montreal.

Emergency responders performed CPR on Wainberg while he was rushed to hospital, where he died shortly thereafter.

Officials say the water conditions in the area were “red flagged” on Tuesday to indicate high surf.

Police officials could not confirm if Wainberg drowned or if he died from another medical condition. The local coroner is expected to determine the cause of death.

Wainberg was the first scientist in Canada to focus solely on HIV research when the virus was emerging in the early 1980s, and he co-chaired the International AIDS conference in 1984. He was also among the first in the world to highlight a problem with HIV drug resistance.

Wainberg is likely best known for his part in discovering an anti-viral drug called 3TC, also known as Epivir and Lamivudine, at the height of the HIV/AIDS crisis in 1989. The drug is used alongside other medications to treat infections caused by HIV.

A native Montrealer, Wainberg was considered a global leader in the fight against HIV/AIDS. At the time of his death, he was the head of AIDS research at Montreal's Jewish General Hospital and the McGill University AIDS Centre. He also served as president of the International AIDS Society from 1998 to 2000 and helped organize the International Congress on AIDS in South Africa in 2000.

Colleagues remembered Wainberg as a passionate scientist who was dedicated to his work, but also had a humorous streak.

“We are 35 years after the discovery of AIDS and Dr. Wainberg would talk about AIDS like it was in the first days. And his passion, he could transfer his passion to colleagues, to young doctors – and (he was) always funny,” said Dr. Rejean Thomas of the Clinique Medical L’Actuel.

Thomas said he saw Wainberg just last week at a conference, where Wainberg said he had no plans to retire anytime soon.

Wainberg is also known for advocating to change a controversial policy in Canada that barred all gay men from donating blood. In a 2010 article published in the Canadian Medical Association Journal, Wainberg and his co-authors suggested the policy should be modified to allow gay men in long-term, monogamous relationships to donate blood.

The rules were later changed so that gay men who abstained from sex within the past five years could donate blood. In 2016, that time frame was reduced to one year. Canadian Blood Services has said it is exploring the possibility of “behaviour-based” screening in the future.

It’s been nearly 30 years since Wainberg helped discover 3TC, a drug that was at the “cutting edge” of HIV research and helped guide global understanding of the epidemic, according to the executive director of the Canadian AIDS Society.

“It’s a huge loss globally in the fight against AIDS,” Gary Lacasse told CTV News Channel on Wednesday.

In 2001, Wainberg made an officer of the Order of Canada for his lifelong dedication to the field of HIV/AIDS research. He was also awarded the Order of Quebec in 2005 and named a Chevalier of France’s Legion d’honneur in 2008.

According to his profile on the Jewish General Hospital, Wainberg’s research focus at the time of his death was on finding “novel concepts” to prevent HIV infection in developing countries. He also said that first-world countries must do more to help pay for lifesaving drugs for people living with HIV/AIDS in poor nations.

Members of Canada’s science, medicine and LGBT communities mourned Wainberg’s sudden passing online.

With files from The Canadian Press and CTV Montreal