Scientists identified a type of chimpanzee in West Africa as the source of HIV infection in humans. The virus most likely jumped to humans when humans hunted these chimpanzees for meat and came into contact with their infected blood. Over several years, the virus slowly spread across Africa and later into other parts of the world
HIV was first identified in the United States in 1981 after a number of gay men started getting sick with a rare type of cancer. It took several years for scientists to develop a test for the virus, to understand how HIV was transmitted between humans, and to determine what people could do to protect themselves. During the early 1980s, as many as 150,000 people became infected with HIV each year. By the early 1990s, this rate had dropped to about 40,000 each year, where it remains today.
AIDS cases began to fall dramatically in 1996, when new drugs became available. Today, more people than ever before are living with HIV/AIDS. CDC estimates that about 1 million people in the United States are living with HIV or AIDS. About one quarter of these people do not know that they are infected: not knowing puts them and others at risk.
Binding - HIV searches for cells that have CD4 surface receptors. Main target is the T4-lymphocyte. The T4-cell is responsible for warning your immune system that there are invaders in the system.
Reverse Transcription- Makes a DNA copy of the virus’s RNA. Can be blocked by Nucleoside Reverse Transcriptase Inhibitors (NRTIs) and Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Integration - The HIV DNA is then carried to the cell’s nucleus. When the cell makes new proteins, it accidentally makes new HIVs. Integration can be blocked by integrase inhibitors, a new class of drugs that are in the earliest stage of research.
Transcription - Once HIV’s genetic material is inside the cell’s nucleus, it directs the cell to produce new HIV. The strands of viral DNA nucleus separate and special enzymes create messenger RNA (mRNA). This can be blocked by antisense antiviral or transcription inhibitors (Tis) new classes of drugs that are in the earliest of research.
Translation- The mRNA carries instructions for making new viral proteins from the nucleus.
Viral Assembly and Maturation- The virus becomes an infection and each infected cell can produce lots of new viruses. Viral assembly can be blocked by Protease Inhibitors (PIs).
It can take some time for the immune system to produce enough antibodies for the antibody test to detect, and this time period can vary from person to person. This time period is commonly referred to as the “window period.”
Most people will develop detectable antibodies within 2 to 8 weeks (the average is 25 days). Even so, there is a chance that some individuals will take longer to develop detectable antibodies.
Therefore, if the initial negative HIV test was conducted within the first 3 months after possible exposure, repeat testing should be considered >3 months after the exposure occurred to account for the possibility of a false-negative result. Ninety-seven percent of persons will develop antibodies in the first 3 months following the time of their infection. In very rare cases, it can take up to 6 months to develop antibodies to HIV.
EIA (enzyme immunoassay) used on blood drawn from a vein, is the most common screening test used to look for antibodies to HIV. A positive (reactive) EIA must be used with a follow-up (confirmatory) test such as the Western blot to make a positive diagnosis. There are EIA tests that use other body fluids to look for antibodies to HIV. These include:
Oral Fluid Tests – use oral fluid (not saliva) that is collected from the mouth using a special collection device. This is an EIA antibody test similar to the standard blood EIA test. A follow-up confirmatory Western Blot uses the same oral fluid sample.
Urine Tests – use urine instead of blood. The sensitivity and specificity (accuracy) are somewhat less than that of the blood and oral fluid tests. This is also an EIA antibody test similar to blood EIA tests and requires a follow-up confirmatory Western Blot using the same urine sample.
A rapid test is a screening test that produces very quick results, in approximately 20 minutes. Rapid tests use blood from a vein or from a finger stick, or oral fluid to look for the presence of antibodies to HIV. As is true for all screening tests, a reactive rapid HIV test result must be confirmed with a follow-up confirmatory test before a final diagnosis of infection can be made.
Home Testing Kits
The testing procedure involves pricking a finger with a special device, placing drops of blood on a specially treated card, and then mailing the card in to be tested at a licensed laboratory. Customers are given an identification number to use when phoning in for the results. All individuals receiving a positive test result are provided referrals for a follow-up confirmatory test, as well as information and resources on treatment and support services.
RNA tests look for genetic material of the virus and can be used in screening the blood supply and for detection of very early infection rare cases when antibody tests are unable to detect antibodies to HIV.
HIV stands for human immunodeficiency virus. This is the virus that causes AIDS. HIV is different from most other viruses because it attacks the immune system. The immune system gives our bodies the ability to fight infections. HIV finds and destroys a type of white blood cell (T cells or CD4 cells) that the immune system must have to fight disease.
HIV destroys a certain kind of blood cell (CD4+ T cells) which is crucial to the normal function of the human immune system. In fact, loss of these cells in people with HIV is an extremely powerful predictor of the development of AIDS. Studies of thousands of people have revealed that most people infected with HIV carry the virus for years before enough damage is done to the immune system for AIDS to develop.
However, sensitive tests have shown a strong connection between the amount of HIV in the blood and the decline in CD4+ T cells and the development of AIDS. Reducing the amount of virus in the body with anti-retroviral therapies can dramatically slow the destruction of a person’s immune system.
AIDS stands for acquired immunodeficiency syndrome. AIDS is the final stage of HIV infection. It can take years for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened the immune system to the point at which the body has a difficult time fighting infections. When someone has one or more of these infections and a low number of T cells, he or she has AIDS.
The following is a list of AIDS-related infections and cancers that people with AIDS acquire as their CD4 count decreases. Previously, having AIDS was defined as having HIV infection and getting one of these additional diseases. Now it is additionally defined as a CD4 count below 200, even without an opportunistic infection. Many other illnesses and corresponding symptoms may develop in addition to those listed here.
Normal Values- in a healthy adult, a normal CD4 count can vary a great deal but is typically 600-1200 cells per cubic millimeter of blood
Between 600 and 350 – in an HIV+ person, this range is considered “very good”. HIV medications are typically not indicated.
Between 350-200 -the immune system is weakened and therefore the HIV+ person may be at increased risk for infection and illness. May start taking HIV medications.
Less than 200 – The immune system is severely weakened and the HIV+ person is at much greater risk of opportunistic infections. HIV medications and prophylactic antibiotics will be prescribed to help prevent illnesses and infections. The patient be classified as having AIDS.
Herpes simplex virus -- causes ulcers/vesicles in the mouth or genitals, occurring more frequently and more severely in an HIV-infected patient than before HIV infection
Tuberculosis -- infection by the tuberculosis bacteria that predominately affects the lungs, but can affect other organs such as the bowel, lining of the heart or lungs, brain, or lining of the central nervous system
Oral or vaginal thrush -- yeast infection of the mouth or genitals
Herpes zoster (Shingles) -- ulcers/vesicles over a discrete patch of skin caused by the varicella zoster virus
Non-Hodgkin's lymphoma -- cancer of the lymph glands
Kaposi's sarcoma -- Cancer of the skin, lungs, and bowel, associated with a herpes virus (HHV-8). Can occur at any CD4 count, but more likely at lower CD4 counts, and more common in men than women
Asymptomatic HIV infection is a phase of chronic infection with human immunodeficiency virus (HIV) during which there are no symptoms of HIV infection.
The length of this phase varies from person to person. It depends on how quickly the HIV virus is copying itself and the genetic differences that affect the way the immune system handles the virus.
Some people can go 10 years or longer without symptoms, while others may have symptoms and worsening immune function within a few years after the original infection.
People with asymptomatic infection can progress to symptomatic HIV infection and develop opportunistic infections associated with HIV. In addition, pregnant women with asymptomatic HIV infection can still transmit HIV to their fetus.
People who are asymptomatic but who have CD4 lymphocyte counts of less than 200 should be on therapy.
Persons infected with HIV-2, immunodeficiency seems to develop more slowly and to be milder. Compared with persons infected with HIV-1, those with HIV-2 are less infectious early in the course of infection.
Both HIV-1 and HIV-2 have the same modes of transmission and are associated with similar opportunistic infections and AIDS.
As the disease advances, HIV-2 infectiousness seems to increase; however, compared with HIV-1, the duration of this increased infectiousness is shorter. HIV-1 and HIV-2 also differ in geographic patterns of infection; the United States has few reported cases.
HIV-2 is highly concentrated in West Africa countries such as Senegal, Nigeria, Ghana, and the Ivory Coast. HIV-2 also spreads to other parts of the world but predominantly to those countries having strong ties to West Africa.