AIDS is the most advanced form of HIV infection. With early diagnosis and effective treatment, few people with HIV will develop AIDS. If there's any chance you may be infected with HIV, you should be tested as soon as possible. There are medicines that can help keep the virus in check, keep it from damaging your immune system further, and help to repair damage done so far. The number of people 50 years and older living with HIV has increased, in part, because of combination antiretroviral medicine therapy.

You can't get HIV by shaking hands, casually kissing or hugging, or being coughed or sneezed on. The virus is not passed on from a toilet seat, doorknobs, dishes, drinking glasses, food, or pets. HIV is passed from one person to another through body fluids. These are blood, semen, and vaginal fluids. The virus can be passed on most readily during vaginal, oral, and anal sex if you are not using a latex condom. It is can also be spread by sharing needles, syringes, or both with someone who is infected with HIV. Others at an increased risk are healthcare workers who can get a stick from a needle containing HIV-infected blood.

You can't tell by how a person looks whether they are infected with HIV. You need to know whether your partner has been tested for HIV, when they were tested, and the results. Also ask if your partner has had a number of different sex partners. Ask if your partner has shared needles, including needles for diabetes medicines. And ask if your partner has had unprotected sex. According to the CDC, if a man has had sex with other men, he should get tested at least once a year. Women should get tested with each new sex partner. Although such questions may be uncomfortable to ask, the information is critical to your health. Before being intimate with a new partner, don't hesitate to insist on an HIV test for a potential partner who has been sexually active or shared needles.

HIV can be passed on by anyone sharing a needle. A person with diabetes who might share a needle to inject insulin or to draw blood to check blood glucose levels is at risk for the virus.

There is only a very slight risk with current screening procedures. According to the CDC, HIV is now very rarely transmitted in the U.S. through a blood transfusion or blood products, even in geographic areas with high rates of HIV. If you got a blood transfusion between 1978 and 1985, before blood was routinely checked for HIV, you should get tested. Also, if you have had an operation or a transfusion in a developing country, no matter what year it was, you should be tested.

That's about 400,000 Americans. Because many older people don't get routinely tested for HIV, the number may be higher.

And many people have no symptoms when they are first infected with HIV or for years afterward. They may even dismiss minor flulike symptoms that can occur several weeks after infection.

Doctors also seldom ask their older patients about their sex lives or their drug use. In turn, older patients are less likely than younger patients to bring up either of these subjects with their doctor. If you are sexually active and worried about HIV, bring up the issue with your healthcare provider.

Older people with HIV are also less likely to join support groups that could help them cope with their illness. They may have more severe cases of depression in response to a diagnosis of HIV than younger patients.

There is no cure for HIV. Early treatment can help improve your health and prevent the development of AIDS. Effective treatment can also help to prevent someone with HIV from passing it on to others. But the best treatment is prevention. Don't have multiple sex partners. Make sure your partner is not infected with HIV. If a potential sexual partner has had sex with others or shared needles, insist on an HIV test before becoming intimate. If you don't have this information, you are putting yourself at risk. Use a condom during sex. Don't share intravenous needles.