Tomorrow marks the 25th annual World Aids Day

Big names, from President Obama to Alicia Keys, are spreading the word about World Aids Day 2012, but a huge number of young people still don’t know their own HIV status. Even though people ages 13 to 24 make up a quarter of new HIV infections in the U.S. every year, a recent CDC report found more than half of them don’t know if they’re carrying HIV. Greatist is here to help provide some basics on HIV, including how, where, and why to get tested.

What It Is — HIV

Human Immunodeficiency Virus (HIV) causes the gradual deterioration of the immune system, meaning the body can’t fight off diseases. The advanced stages of HIV, when the person contracts an opportunistic infection, are known as Acquired Immune Deficiency Syndrome (AIDS). The virus can be transmitted through unprotected sexual intercourse; blood transfusions; sharing needles; or from a mother to her baby during pregnancy, childbirth, or breastfeeding. As of 2009, there were approximately 1.2 million people in the U.S. living with HIV, and about 50,000 new Americans become infected every year.

Get Tested — The How, Where, and Why

It’s always possible to take an HIV test, but doctors advise people who engage in certain sexual risk behaviors (such as having unprotected sex) to get tested at least once a year. Anyone who thinks he/she may have been infected with HIV should get tested as soon as possible. An HIV test is pretty simple — it involves either a blood or oral fluid sample. And while there are home testing kits available, most health experts recommend getting tested in an official healthcare setting. Luckily, finding a testing site is pretty easy, and many institutions even offer free testing. Some tests produce results in only 20 minutes, but others take a few days. Depending on the results, healthcare workers provide counseling on the next steps.

Thankfully, first-timers won’t have to fly solo, since major organizations have pledged their support or launched campaigns backing World Aids Day 2012. For example, Durex is donating one condom for every social message tagged with #1share1condom, (RED) is hosting a live-streamed dance party, ONE has created a digital wall where users can pledge actions, and the World Aids Campaign is acting as a hub for a slew of relevant initiatives.

If you think you might have been infected with HIV or just want to play it safe, check out this website to find a testing site near you. In the meantime, learn more about HIV and AIDS here and find out how you can join the campaign against HIV and AIDS tomorrow and all year long.

Durex’s #1Share1Condom

Will a massive event like World Aids Day truly help reach the goal of “Getting to Zero?” Let us know in the comments below or tweet the author at @ShanaDLebowitz.