Human immunodeficiency virus or HIV is a viral infection of the immune system. Acquired immune deficiency disease (AIDS) is the umbrella term used to describe the final stage of an HIV infection. HIV is a sexually transmitted infection, but HIV can also be transmitted by contaminated hypodermic needles and blood transfusions, as well as from mother to child during pregnancy, delivery, and breastfeeding. Early symptoms of an HIV infection include fever, rash, night sweats, headaches, sore throat, fatigue, and a general feeling of having the flu, but many individuals who are HIV positive do not have any symptoms. This is because the virus has a latency stage, also known as the chronic phase. The virus can lay dormant inside your cells for years. HIV is a human retrovirus. The term retrovirus means that the virus can replicate inside a human cell. The retrovirus is an RNA virus; it converts itself into DNA and inserts itself into the cell’s genome. Once it is part of the cell’s genetic code, the virus is then produced by the cell’s replication machinery. Once enough of the virus has been produced within the cell, the cell dies and releases the virus into the body. HIV attacks the cells of your immune system, specifically the CD4 cells. CD4 cells include T helper cells, monocytes, macrophages, and dendritic cells. The virus decreases the number CD4 cells in the body, therefore diminishing the body’s ability to fight infection. Once your number of CD4 cells has fallen below 200 per cubic millimeter of blood, you will be diagnosed with AIDS. There is no cure for an HIV infection or AIDS. There are treatments that can suppress the HIV virus and help to slow the progression of the disease.