HIV stands for human immunodeficiency virus, which is the virus that causes HIV infection. The acronym “HIV” can refer to the virus or to HIV infection. The virus attacks and destroys the infection-fighting CD4 cells of the human immune system. CD4 cells are a type of white blood cells that play a major role in protecting the body from infection. The gradual loss of these cells makes it difficult for the body to fight off common or serious infections and certain cancers. The HIV uses the machinery of these cells to multiply and spread throughout the body. This process, which is carried out in seven stages, is called the HIV life cycle, and consists of binding, fusion, reverse transcription, integration, replication, assembly and budding.

The virus is spread from person to person through contact with blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, or breast milk of a person with HIV. Other means of transmission is via sharing injection drug equipment, such as needles, with a person who has HIV. The spread of the virus from an infected woman to her child during pregnancy, childbirth, or breastfeeding is called mother-to-child transmission of HIV. Without treatment, HIV can gradually destroy the immune system and advance to AIDS.

There are three (3) stages of the HIV infection viz an acute phase, a chronic phase and a phase of AIDS, i.e. acquired immunodeficiency syndrome. Acute HIV infection is the earliest stage of the infection, and it generally develops within 2 to 4 weeks after an infection with HIV. During this time, some people have flu-like symptoms, such as fever, headache, and rash, the virus multiplies rapidly and spreads throughout the body, and the level of the virus in the blood is very high, which greatly increases the risk of HIV transmission. The second stage of the infection is chronic phase, asymptomatic or clinical latency phase. During this stage, the virus continues to multiply in the body but at very low levels. People with chronic HIV infection may not have any HIV-related symptoms. AIDS is the final, most severe stage of the infection. In this stage, the immune system has been severely damaged, and the body cannot off opportunistic infections (infections and infection-related cancers that occur more frequently or are more severe in people with a weakened immune system than in people with healthy immune systems.) People with HIV are diagnosed with AIDS if they have a CD4 count of less than 200 cells/mm3 or if they have certain opportunistic infections.

There is no cure for HIV, but treatment with HIV medicines (antiretroviral drugs) can slow or prevent the infection from advancing from one stage to the next. PLHIV take a combination of the HIV medicines, in a form of a regimen every day. The drugs protect the immune system by blocking the virus at different stages of the HIV life cycle. ARVs are grouped into different drug classes according to how they fight the virus. Each class of drugs is designed to target a specific step in the HIV life cycle.

ARVs help PLHIV live longer and healthier lives. One of the main goals of the treatment is to reduce a person's viral load to an undetectable level (a level of the HIV in the blood that is too low to be detected by a viral load test), and ultimately reducing the transmission of the virus from persons to persons.