It’s been more than 30 years since a disease now called AIDS was first recognized in the United States. Back then, it was considered a death sentence. No treatments were available, its cause was unknown, and people often died within a few months after being diagnosed. Today, people infected with HIV—the virus that causes AIDS—can live full, healthy lives, in large part because of medicines and other discoveries made with NIH support.
The terms HIV and AIDS can be confusing, because they’re related but different. HIV is a virus that harms your immune system by invading and then destroying your infection-fighting white blood cells. AIDS is the final stage of an untreated HIV infection. People with AIDS can have a range of symptoms, because their weakened immune systems put them at risk for life-threatening infections and cancers.
HIV virus passes from one person to another through certain body fluids, such as blood and semen. About 90% of new HIV infections in the U.S. occur during sex. Shared needles and injection drug use is the second most common route of infection. HIV can also spread from an infected mother to her newborn. HIV isn’t spread through casual contact, such as shaking hands, hugging, sneezing, sharing utensils, or using bathrooms.