It’s been 35 years since researchers from the U.S. Centers for Disease Control and Prevention first reported on a mysterious illness that was infecting and killing healthy young men.

The CDC report from 1981 was the first time AIDS was ever mentioned in medical literature.

In those early days, little was known about AIDS. Today, researchers understand a great deal about how HIV (the human immunodeficiency virus) attacks the immune system and advances to become AIDS. While treatment, prevention and education have saved many lives, researchers continue to fight the spread of HIV and AIDS and find a cure.

Two Thousand candles were lit in memory of victims of AIDS on World AIDS Day, Dec. 1, 2016 at Gammeltorv Square in Copenhagen, Denmark.more +

Since that CDC report was published, the disease has claimed 35 million lives, according to the the World Health Organization.

Anti-retroviral medication has turned the human immunodeficiency virus (HIV) from a death sentence into a chronic illness for many. However, less than half of the people worldwide with HIV get the treatments needed to prolong their lives.

Approximately 1.1 million people died worldwide from the disease last year, according to the United Nations.

A huge problem in the fight against HIV is the fact that people can go years without exhibiting symptoms. As a result, 12.5 percent of people in the U.S. with HIV are unaware they are infected, according to the CDC.

Worldwide, that number jumps to 40 percent, according to the WHO.

To combat that figure, the WHO announced this week new guidelines to encourage "self testing" for HIV.

People can now test for the virus via a simple oral swab or by pricking their finger from the privacy of their own home.

"Millions of people with HIV are still missing out on life-saving treatment, which can also prevent HIV transmission to others," Dr. Margaret Chan, WHO director-general, said in a statement. "HIV self-testing should open the door for many more people to know their HIV status and find out how to get treatment and access prevention services."

In the U.S., gay and bisexual men of color are at increased risk of contracting HIV. The lifetime risk for black men who are gay or bisexual is 1 in 2, according to the CDC.

Worldwide, more women than men are infected with the disease. HIV is the number one killer of women between the ages of 15 to 49, according to the American Foundation for AIDS Research.

Adolescents are also particularly vulnerable. According to one report, 41,000 adolescents between the ages of 10 to 19 died of the disease in 2015.

"The world has made tremendous progress in the global effort to end AIDS, but the fight is far from over – especially for children and adolescents,” UNICEF Executive Director Anthony Lake said in a statement today. “Every two minutes, another adolescent – most likely a girl – will be infected with HIV. If we want to end AIDS, we need to recapture the urgency this issue deserves — and redouble our efforts to reach every child and every adolescent.”

While there are no cures or vaccines to prevent HIV, there are multiple experimental vaccines currently in the early stages of testing across the globe.

Additionally, scientists are examining if gene therapy could someday lead to a "functional cure" of the virus.