Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive.
HIV infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: First, direct viral killing of infected cells; second, increased rates of apoptosis in infected cells; and third, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that ...view middle of the document...
Two types of HIV have been characterized: HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and termed both LAV and HTLV-III. It is more virulent, more infective, and is the cause of the majority of HIV infections globally. The lower infectivity of HIV-2 compared to HIV-1 implies that fewer of those exposed to HIV-2 will be infected per exposure. Because of its relatively poor capacity for transmission, HIV-2 is largely confined to West Africa.
Early Signs and Symptoms of HIV
* Enlarged lymph nodes in the neck, armpits or groin
Any symptoms from becoming infected typically resolve in one to four weeks.
As you can see, the signs and symptoms of HIV infection are similar to those for many different viral infections. The only way to know for sure if you are infected with HIV is to be tested. Many people infected with HIV do not have any signs and symptoms at all for many years.
Later Signs and Symptoms of HIV/AIDS
The Centers for Disease Control (CDC) says the following signs and symptoms may be warning signs of late-stage HIV infection:
* rapid weight loss
* dry cough
* recurring fever or profuse night sweats
* profound and unexplained fatigue
* swollen lymph glands in the armpits, groin, or neck
* diarrhea lasting more than a week
* white spots or unusual blemishes on the tongue, in the mouth, or in the throat
* red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
* memory loss, depression, and other neurological disorders
HIV destroys the white blood cells that are required to fight infection. As the white cell count falls to dangerous levels, numerous infections and diseases emerge. It is at this point that a person is said to have AIDS (Acquired Immune Deficiency Syndrome).
HIV is transmitted when the virus enters the body, usually by injecting infected cells or semen. There are several possible ways in which the virus can enter.
* Most commonly, HIV infection is spread by having sex with an infected partner. The virus can enter the body through the lining of the vagina, vulva, penis, rectum, or mouth during sex. Although intercourse is the primary risk factor, oral sex transmission is also possible.
* HIV frequently spreads among injection-drug users who share needles or syringes that are contaminated with blood from an infected person.
* Women can transmit HIV to their babies during pregnancy or birth, when infected maternal cells enter the baby's circulation, or through breastfeeding.
* HIV can be spread in health-care settings through accidental needle sticks or contact with contaminated fluids.
* Very rarely, HIV spreads through transfusion of contaminated blood or blood components. All blood products are tested to minimize this risk. If tissues or organs from an...