Human Immunodeficiency Virus (HIV) is a virus that attacks T cells in the immune system. Acquired immunodeficiency syndrome (AIDS) is a syndrome that appears in advanced stages of HIV infection. The difference between HIV and AIDS is that HIV is a virus, while AIDS is a medical condition. HIV is sometimes referred to as the causative agent, as it is not possible to develop AIDS without an HIV infection, although it is possible to become infected with HIV without developing AIDS.
HIV can be transmitted sexually or through blood products. Some common risk factors for HIV infection include: unprotected sex, needle sharing, and exposure to contaminated blood products. Once someone is infected with HIV, the virus begins to replicate in the blood, slowly hijacking T cells so they can't function normally. If the infection is allowed to progress, it will eventually develop into AIDS. People with HIV and AIDS are at higher risk for opportunistic infections because their immune systems are weakened.
AIDS is characterized by infection with HIV Y the presence of one or more opportunistic infections. Toxoplasmosis, uncontrollable candida infections, cytomegalovirus, pneumocystitis pneumonia, and Kaposi's sarcoma are some examples of AIDS-associated infections. In the patient's blood tests, the number of T cells is drastically below normal readings, reflecting the weakened state of the immune system. The HIV virus in the body of an AIDS patient is also still present and infectious, and someone with AIDS can pass HIV to another person.
One might think of the difference between HIV and AIDS in that HIV is a virus while AIDS is a disorder, just as Toxic Shock Syndrome (TSS) is a disorder caused by an infection by staphylococci. Progression from viral infection to full-blown AIDS is highly undesirable, as opportunistic infections that occur can kill the patient. Routine HIV testing can identify the infection in its early stages, allowing the patient to use prophylactic medications that will slow down the rate of replication of the virus and delay the onset of AIDS.
The line between HIV and AIDS has been blurred in popular media, which can be confusing to laypeople. Many clinics, for example, advertise "free AIDS testing" to their clients, when they really mean "free HIV testing." Both HIV and AIDS are also the subject of a great deal of research in the scientific community, with clinicians seeking new treatment approaches for the early stages of HIV infection, as well as AIDS itself.