Transmission of HIV is primarily through sexual intercourse, where infected body fluid such as blood and semen come in contact with unaffected body fluids. Blood contains 1,000 - 100,000 viruses/ mL, and semen contains 10 - 50 viruses/ mL. The virus is not transmitted by casual contact, sharing household items, and generally kissing cannot spread the virus, saliva only contains 1 virus/mL, but there is always a risk (Tortora et al, 2013, p. 551).
For healthcare workers such as myself risk for infection from a needle-stick injury is 0.03%. It is suggested that healthcare workers be vaccinated against Hepatitis-B (HBV). HBV is an opportunistic infection, where those infected with HIV already have a compromised immune system making it more likely for them to have HBV. So by protecting yourself against HBV it can lower your risk for infection if you were to be exposed to body fluids (Hepatitis B vaccine, 2014).
In order to be infected with HIV the virus must go through steps of attachment, fusion, and entry. The virus has a strong correlation with immune system, particularly T helper cells. Helper T cells are the cells in the body that respond and regulate the immune response. On these helper T cells are specific receptors known as CD4+ that are the main target for the HIV infection. As these helper T cells become infected they go through a period of latency within cells that can last for decades, allowing it to hide from the immune system, this is known as latency infected macrophages. There is then the activated macrophage where new viruses are produced and released. These viruses are constantly undergoing rapid antigenic changes forming new variations of the virus making it extremely difficult to treat.
There are 3 clinical phases of HIV infection:
Phase 1- In the first few weeks after infection over 1 billion CD4+ cells will be infected. The infection may be asymptomatic, or cause lymphadenopathy (swollen lymph nodes).
Phase 2- CD4+ T cells decline rapidly. HIV remains latent in cells, only a few infected cells are released. A few symptoms may appear indicating a decline in immune function.
Phase 3- CD4+ T cell count drops below 350 cells/mcL, indicating need for treatment. In a healthy individual a normal T cell count is between 800 and 1,000 cells/mcL. Less than 200 cells/mcL is considered diagnostic for AIDS.