In the past two decades, acquired immune deficiency syndrome (AIDS) has killed more than 25 million people, making it one of the most devastating epidemics in our recorded history.

Nurses throw rose petals and red ribbons to mark advances in the fight against AIDS several days before World AIDS Day at a medical school in Yangzhou, Jiangsu province, China. (China Daily/Reuters)

Dec. 1 marks the 24th anniversary of World AIDS Day. Last year, there were 2.7 million HIV infections, 390,000 of which were children. The message today from health officials and advocacy organizations: Let’s get that number down to zero. “Zero new HIV infections. Zero discrimination. Zero AIDS-related deaths,” is the message from international AIDs & HIV charity

But funding for AIDS programs may be at risk in the current world financial crisis, “accident[s] of geography” lead to devastating results for certain populations, and setbacks remain in discovering an elusive cure.

The world's largest supporter of AIDS programs, The Global Fund to Fight AIDS, Tuberculosis and Malaria, just made a troubling announcement: Due to the global financial crisis, it has fallen well short of its fundraising goals. Many are concerned about what that means for the future of AIDS.

While access to antiretroviral treatment and care in many regions of the world has improved, AIDS is still claiming more than a million lives a year — 1.8 million in 2009, according to UN AIDS, 1 in 7 of which were children.

Bono, a major activist in the fight against AIDS, wrote today of the disparities that have long existed in treatment around the world: “ accident of geography would deny their patients the two little pills a day that could save their lives.” Bono appeared on the “Daily Show” last night to speak about the work that still needs to be done:

Health officials today came out with new recommendations that say people living with HIV should be offered AIDS drugs as soon as they are diagnosed with the virus, which the officials say can prolong life and stem the spread of the disease.

Researchers also announced, however, that the use of antiretroviral drugs to prevent HIV infection, which initially worked in a number of clinical trials, has recently run into problems

Michael Gottlieb, the first physician to describe the new disease that would become known as AIDS, has urged fresh efforts be used against the epidemic. He’ll be online at The Washington Post to chat with readers at 11 a.m. today.

On Twitter, where #WorldAIDSDay and #HIV are trending, many organizations urged people to get tested for HIV and know their status, something 1 in 4 people do not. “You can now get tested for HIV using a saliva sample,” wrote on its Web site. “You can get the results of an HIV test in just 15-20 minutes.”

Other organizations sent out reminders of the number of babies born HIV positive every day, without having had a choice. “By 2015, it can be 0,” JoinRed, an organization that fights AIDS in Africa, wrote.

Some who had been tested for HIV also spoke out on Twitter, including one man who wrote: “I kinda like approaching World AIDs day with the confidence of a HIV- man. Can’t recall when last I panicked.”

For the past 16 years, the president of the United States has made an official proclamation on World AIDS Day. Today, he did the same. Watch the video:

If you have a friend of family member who has lost their life to AIDS, you can honor them by sharing their story here.

Below, see photos of those marking World AIDS Day around the globe:

Children attend a school class at the Nyumbani Children's Home for children with HIV, in Karen on the outskirts of Nairobi, Kenya, Wednesday, Nov. 30, 2011. The orphanage, which is heavily reliant on foreign donations, cares for more than 100 children with HIV — whose parents died of the disease — and provides them with housing, care, and antiretroviral medicine to stem the progress of the disease. (Ben Curtis/AP)

Click on the gallery below to see more photos on World Aids Day.

View Photo Gallery: People across the globe gather to mark the 24th annual World AIDS Day.

Read more of today’s stories from around the world:

- Europe shows signs of slowing growth

-India and China face mutual antipathy

-Clinton offers reform incentives to Burma

-To China, U.S. envoy is a rising star

-See more of our foreign coverage