What is HIV?
Human Immunodeficiency Virus (HIV) is the virus that causes AIDS. HIV weakens the immune system and leaves the body vulnerable to many infections and cancers that rarely develop in someone with a healthy immune system. A person living with HIV may have no symptoms of HIV for many years; however, over time most HIV-positive persons experience progression of their disease and develop symptoms related to immune system dysfunction if HIV is not diagnosed and treated with effective medications. With the proper medications and medical care, a person living with HIV can now lead a long, healthy life.
What is AIDS?
Acquired Immune Deficiency Syndrome (AIDS) is the late stage of HIV infection. By the time a diagnosis of AIDS is made, HIV has already seriously damaged the body’s immune system. Before the use of effective treatment, it commonly took 8-10 years from the time a person was initially infected with HIV to a diagnosis with AIDS. People who have AIDS may need medications that help to prevent certain common infections (called opportunistic infections) in addition to effective HIV treatment while their immune system is weak. Today, if a person living with HIV is diagnosed early (before HIV can seriously damage the immune system) and remains on effective treatments for HIV, they may never develop AIDS.
How is HIV transmitted?
HIV is transmitted when blood, sexual fluids (e.g. semen, vaginal fluid, “pre-cum,” or rectal mucous), or breast milk that contains HIV enters another person’s body. This most often occurs during condomless sex or during injection drug use, when needles or other equipment used to inject drugs (e.g. syringes, cottons, or cookers) are shared. HIV can also be transmitted from an HIV-positive mother to her infant during pregnancy or delivery, or from breastfeeding. Anyone who has HIV can transmit the virus, whether or not he/she is aware they carry the virus, appears sick, or has an AIDS diagnosis. There are many highly effective methods of preventing HIV transmission via sex, blood-to-blood contact, or from mother to child (see the Preventing HIV Transmission section); however, preventing new cases of HIV requires that individuals at risk of HIV receive HIV testing regularly and that both HIV-positive and HIV-negative individuals are proactive in protecting themselves and others.
HIV is spread in the following ways:
- Unprotected sexual intercourse – HIV can enter the body during sex through the mucous membranes of the anus, vagina, penis (urethra), or mouth, and through cuts, sores, and abrasions on the skin. Unprotected anal and vaginal sex are the riskiest sexual activities. There are a small, but growing, number of reported cases of HIV transmission through oral sex; however, the risk of oral sex transmission is lower than that for anal or vaginal sex. With each of these practices, the receptive partner (vagina, anus, mouth) is at greater risk; however, the inserting partner is also at risk.
- Injection drug use – Sharing needles or using non-sterile needles and syringes carries a high risk of HIV transmission. Sharing cookers, cottons, and water for mixing/bleaching can also transmit HIV. After use, small amounts of blood can remain in the used needles, syringes, cookers, and cottons. Blood may also remain in the water used for mixing drugs or bleaching equipment. This remaining blood can enter the body of the next user when any of these items are shared. If this blood is HIV infected, transmission can easily occur.
- From an HIV-positive mother to her infant – HIV can be transmitted from mother to child during pregnancy, during birth, or through breast-feeding. Before treatment with antiretroviral medications to prevent transmission became routine, about 1 in 4 babies born to HIV-positive women became infected. Now, with effective treatment during pregnancy and delivery, the HIV transmission rate from an HIV-positive mother to her baby is less than 1 in 100. Consequently, all pregnant women should see their doctor, be tested for HIV, and obtain recommended treatment.
HIV is rarely transmitted in the following ways:
- Blood transfusions and organ transplants – The risk of acquiring HIV from a blood transfusion today is exceedingly rare; it has been estimated at between 1 per 200,000-2,000,000 transfusions [Goodnough, NEJM 340:438]. The risk of acquiring HIV from an organ transplant is probably similar. Before 1985, there were no tests to screen blood and organ donations for HIV. Today, blood and organ banks screen out most potential donors who are likely to be at risk for HIV infection in advance. Accepted donors and their blood are then extensively tested to rule out infection with HIV and other blood-borne germs.
- The health care setting – There is a very small, but real, risk of health care workers getting HIV from patients as a result of needle stick accidents and other substantial blood exposures. The risk of patients getting infected from health care workers is exceedingly small.
HIV is not transmitted by:
- Casual contact – HIV is not spread by casual contact. It dies quickly outside the body and is easily killed by soap and by common disinfectants such as bleach. There is no risk of HIV infection from:
- donating blood
- mosquito bites
- toilet seats
- shaking hands
- hugging or kissing
- touching or skin-to-skin contact
- sharing eating utensils
- food or objects handled by people with HIV or AIDS
- spending time in the same house, business, or public place with a person with HIV/AIDS