"The biggest problem in caring for those with AIDS is no longer mainly a medical or scientific problem -- the crisis is access to affordable drugs," Bernie Sanders said in a statement.
"People are dying in America because they can't afford to pay the outrageous prices for medicine they need to live. In the richest nation in the world, we must do everything possible to get people the medicine they need at a price they can afford," the Democratic candidate added, noting one in five Americans -- 35 million people -- are unable to afford to fill their prescriptions.
Ben Carson said the progress the medical community has made in treating HIV and AIDS is "remarkable."
"But the work is far from over," the retired neurosurgeon told CNN on Tuesday. "We must continue to drive research into newer, better treatments that can protect and prolong life. We must work with international charities and organizations to make treatment and prevention more accessible across the globe."
Hillary Clinton's campaign tweeted a video of her work as secretary of state addressing the international AIDS crisis.
"Let's commit to an AIDS-free generation: invest in research, fight discrimination, and expand access to lifesaving drugs," Clinton tweeted.
Another Democratic hopeful, Martin O'Malley, said working to stem AIDS across the globe will "demonstrate the generosity and compassion of the American people."
"As President, I will redouble our efforts in HIV research, treatment, and prevention, and work with our allies to end the scourge of AIDS," O'Malley said in a statement to CNN. "We can save lives, families, and communities across the globe. We can also demonstrate the generosity and compassion of the American people."
CNN has reached out to a number of Republican presidential candidates for comment on World AIDS Day.
HIV has killed an estimated 39 million people to date and is at epidemic levels globally, CNN has reported