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This entry was posted in Health Services and tagged Human Immune deficiency on January 9, 2015 by sunnylizlinq fluent opinioni
Â HIV is a virus that attacks the immune system and damages the bodys ability to fight infections. AIDS is a potentially fatal condition that develops in the most advanced stage of HIV.
HIV disease staging and classification systems are critical tools for tracking and monitoring the HIV epidemic and for providing clinicians and patients with important information about HIV disease stage and clinical management. Two major classification systems currently are in use: the U.S. Centers for Disease Control and Prevention (CDC) classification system and the World Health Organization (WHO) Clinical Staging and Disease Classification System. The CDC disease staging system (most recently revised in 1993) assesses the severity of HIV disease by CD4 cell counts and by the presence of specific HIV-related conditions. The WHO system classifies HIV disease on the basis of clinical manifestations that can be recognized and treated by clinicians in diverse settings, including resource-constrained settings, and by clinicians with varying levels of HIV expertise and training.
Scientists believe HIV came from a particular kind of chimpanzee in Western Africa. Humans probably came in contact with HIV when they hunted and ate infected animals. Recent studies indicate that HIV may have jumped from monkeys to humans as far back as the late 1800s.
HIV is transmitted in body fluids that contain free virions and infected CD4 + T cells. These fluids include blood, seminal fluid, vaginal secretions, amniotic fluid, and breast milk. Inflammation and breaks in the skin or mucosa result in the increased probability that an exposure to HIV will lead to infection. The amount of HIV and infected cells in the body fluid is associated with the probability that the exposure will result in infection. Mother to child transmission of HIV may occur in utero, at time of delivery, or through breast feeding, but most perinatal infections are thought to occur after exposure during delivery.
Anatomy and Physiology Of The Immune System (HIV)
The immune system protects the body by recognizing antigens on invading bacteria and viruses and reacting to them. An antigen is any substance that induces a state of sensitivity and immune responsiveness. These antigens interact with antibodies and immune cells, initiating an immune response. This process destroys the antigen, allowing the body to be free of infections. Types of antigens include bacteria, viruses, fungi, and parasites. When the immune system is weakened or destroyed by a virus such as HIV, the body is left vulnerable to infections.
The immune system consists of lymphoid organs and tissues, including the bone marrow, thymus gland, lymph nodes, spleen, tonsils, adenoids, appendix, blood, and lymphatic vessels. All components of the immune system are vital in the production and development of lymphocytes, or white blood cells.
Innate, or nonspecific, immunity is the defense system with which you were born. It protects you against all antigens. Innate immunity involves barriers that keep harmful materials from entering your body. These barriers form the first line of defense in the immune response. Examples of innate immunity include:
Enzymes in tears and skin oils
Mucus, which traps bacteria and small particles
Innate immunity also comes in a protein chemical form, called innate humoral immunity. Examples include the bodys complement system and substances called interferon and interleukin-1 (which causes fever).
If an antigen gets past these barriers, it is attacked and destroyed by other parts of the immune system.
Acquired immunity is immunity that develops with exposure to various antigens. Your immune system builds a defense against that specific antigen.
Passive immunity is due to antibodies that are produced in a body other than your own. Infants have passive immunity because they are born with antibodies that are transferred through the placenta from their mother. These antibodies disappear between ages 6 and 12 months.
Passive immunization may also be due to injection of antiserum, which contains antibodies that are formed by another person or animal. It provides immediate protection against an antigen, but does not provide long-lasting protection. Immune serum globulin (given for hepatitis exposure) and tetanusÂ antitoxin are examples of passive immunization.
The immune system includes certain types of white blood cells. It also includes chemicals and proteins in the blood, such as antibodies, complement proteins, and interferon. Some of these directly attack foreign substances in the body, and others work together to help the immune system cells.
Lymphocytes are a type of white blood cell. There are B and T type lymphocytes.
B lymphocytes become cells that produce antibodies. Antibodies attach to a specific antigen and make it easier for the immune cells to destroy the antigen.
T lymphocytes attack antigens directly and help control the immune response. They also release chemicals, known as cytokines, which control the entire immune response.
As lymphocytes develop, they normally learn to tell the difference between your own body tissues and substances that are not normally found in your body. Once B cells and T cells are formed, a few of those cells will multiply and provide memory for your immune system. This allows your immune system to respond faster and more efficiently the next time you are exposed to the same antigen. In many cases it will prevent you from getting sick. For example, a person who has had chickenpox or has been immunized against chickenpox is immune from getting chickenpox again.
The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals including histamine, bradykinin, and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling. This helps isolate the foreign substance from further contact with body tissues.
The chemicals also attract white blood cells called phagocytes that eatÂ germs and dead or damaged cells. This process is called phagocytosis. Phagocytes eventually die. Pus is formed from a collection of dead tissue, dead bacteria, and live and dead phagocytes.
HIV-1 and HIV-2 are retroviruses in the Retroviridae family, Lentivirus genus. They are enveloped, diploid, single-stranded, positive-sense RNA viruses with a DNA intermediate, which is an integrated viral genome (a provirus) that persists within the host-cell DNA.
The specific details of the disease process that leads to AIDS are not fully understood despite considerable progress in the virology of HIV and the immunology of the human host, much of which has been driven by the urge to better understand AIDS.
There is a specific decline in the CD4+ helper T cells, resulting in inversion of the normal CD4/CD8 T-cell ratio and dysregulation of B-cell antibody production. Immune responses to certain antigens begin to decline, and the host fails to adequately respond to opportunistic infections and normally harmless commensal organisms. Because the defect preferentially affects cellular immunity, the infections tend to be nonbacterial (fungal, viral).
Primary infection â¨The majority of people infected by HIV develop a flu-like illness within a month or two after the virus enters the body. This illness, known as primary or acute HIV infection, may last for a few weeks. Possible symptoms include:
Swollen lymph glands, mainly on the neck
Although the symptoms of primary HIV infection may be mild enough to go unnoticed, the amount of virus in the blood stream (viral load) is particularly high at this time. As a result, HIV infection spreads more efficiently during primary infection than during the next stage of infection.
Clinical latent infection â¨In some people, persistent swelling of lymph nodes occurs during clinical latent HIV. Otherwise, there are no specific signs and symptoms. HIV remains in the body, however, as free virus and in infected white blood cells.
Clinical latent infection typically lasts eight to 10 years. A few people stay in this stage even longer, but others progress to more-severe disease much sooner.
Early symptomatic HIV infection â¨As the virus continues to multiply and destroy immune cells, you may develop mild infections or chronic symptoms such as:
Swollen lymph nodes â often one of the first signs of HIV infection
Progression to AIDS â¨If you receive no treatment for your HIV infection, the disease typically progresses to AIDS in about 10 years. By the time AIDS develops, your immune system has been severely damaged, making you susceptible to opportunistic infections â diseases that wouldnt trouble a person with a healthy immune system. The signs and symptoms of some of these infections may include:
Shaking chills or fever higher than 100 F (38 C) for several weeks
Persistent white spots or unusual lesions on your tongue or in your mouth
HIV is most commonly diagnosed by testing your blood or saliva for the presence of antibodies to the virus. Unfortunately, these types of HIV tests arent accurate immediately after infection because it takes time for your body to develop these antibodies â usually up to 12 weeks. In rare cases, it can take up to six months for an HIV antibody test to become positive.
A newer type of test checks for HIV antigen, a protein produced by the virus immediately after infection. This test can confirm a diagnosis within days of infection. An earlier diagnosis may prompt people to take extra precautions to prevent transmission of the virus to others. There is also increasing evidence that early treatment may be of benefit.
Tests to tailor treatment â¨If you receive a diagnosis of HIV/AIDS, several types of tests can help your doctor determine what stage of the disease you have. These tests include:
CD4 count. CD4 cells are a type of white blood cell thats specifically targeted and destroyed by HIV. A healthy persons CD4 count can vary from 500 to more than 1,000. Even if a person has no symptoms, HIV infection progresses to AIDS when his or her CD4 count becomes less than 200.
Viral load. This test measures the amount of virus in your blood. Studies have shown that people with higher viral loads generally fare more poorly than do those with a lower viral load.
Drug resistance. This blood test determines whether the strain of HIV you have will be resistant to certain anti-HIV medications and the ones that may work better.