HIV (Human immunodeficiency virus)

HIV (Human immunodeficiency virus)

Human immunodeficiency virus. The term "HIV" has been internationally accepted in the scientific community as the appropriate name for the retrovirus that is the causative agent of AIDS.
HIV is a virus which attacks the immune system and prevents it from functioning. It can be transferred from human to human via blood and bodily fluids.
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 letdown of the immune system allows life-threatening opportunistic infections and cancers to prosper. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four most important routes of transmission are unsafe sex, unhygienic needles, breast milk, and transmission from an infected mother to her baby at birth (perinatal transmission).
HIV infection in humans is considered pandemic by the World Health Organization (WHO). Nevertheless, satisfaction about HIV may play a key role in HIV risk. From its discovery in 1981 to 2006, AIDS killed over 25 million people. HIV infects about 0.6% of the world's population. In 2009, AIDS claimed an estimated 1.8 million lives, down from a global peak of 2.1 million in 2004. In the order of 260,000 children died of AIDS in 2009. A disproportionate number of AIDS deaths occur in Sub-Saharan Africa, retarding economic growth and growing poverty. In 2005, it was estimated that HIV would infect 90 million people in Africa, resulting in a minimum estimate of 18 million orphans.

History of HIV

The history of the human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) dates back to 1981, when homosexual men with symptoms of a disease that now are considered typical of AIDS were primary described in Los Angeles and New York. The men had an unusual type of lung infection (pneumonia) called Pneumocystis carinii (now known as Pneumocystis jiroveci) pneumonia (PCP) and rare skin tumors called Kaposi's sarcomas. The patients were renowned to have a severe reduction in a type of cell in the blood (CD4 cells) that is a vital part of the immune system. These cells, often referred to as T cells, help the body fight infections. Shortly thereafter, this disease was familiar throughout the United States, Western Europe, and Africa. In 1983, researchers in the United States and France described the virus that causes AIDS, now known as HIV, belonging to the group of viruses called retroviruses. While HIV infection is required to develop AIDS, the actual definition of AIDS is the development of a low CD4 cell count (<200 cells/mm3) or any one of a long list of complications of HIV infection ranging from a variety of so-called "opportunistic infections," cancers, neurologic symptoms, and wasting syndromes.

AIDS

When CD4+ T cell numbers decline lower a dangerous level of 200 cells per µL, cell-mediated immunity is vanished, and infections with a variety of opportunistic microbes appear. The first symptoms often include moderate and unexplained weight loss, recurring respiratory tract infections (such as sinusitis, bronchitis, otitis media, pharyngitis), prostatitis, skin rashes, and oral ulcerations.
Common opportunistic infections and tumors, the greater parts of which are normally controlled by robust CD4+ T cell-mediated immunity then start to affect the patient. Typically, resistance is vanished early on to oral Candida species and to Mycobacterium tuberculosis, which leads to an increased susceptibility to oral candidiasis (thrush) and tuberculosis. Later, reactivation of latent herpes viruses may cause worsening recurrences of herpes simplex eruptions, shingles, Epstein-Barr virus-induced B-cell lymphomas, or Kaposi's sarcoma.
HIV spread (transmitted)
HIV is present to changeable degrees in the blood and genital secretions of virtually all individuals infected with HIV, regardless of whether or not they have symptoms. The spread of HIV can occur when these secretions come in contact with tissues such as those lining the vagina, anal area, mouth, eyes (the mucus membranes), or with a break in the skin, such as from a cut or puncture by a needle. The most common ways in which HIV is spreading throughout the world include sexual contact, sharing needles, and by transmission from infected mothers to their newborns during pregnancy, labor (the delivery process), or breastfeeding. (See the section below on treatment during pregnancy for a discussion on reducing the risk of transmission to the newborn.)
Sexual transmission of HIV has been described from men to men, men to women, women to men, and women to women through vaginal, anal, and oral sex. The best way to avoid sexual transmission is abstinence from sex until it is certain that both partners in a monogamous relationship are not HIV-infected. Because the HIV antibody test can take months to turn positive after infection occurs, both partners would need to investigation negative for at least 12 and up to 24 weeks after their last potential exposure to HIV.
The spread of HIV by exposure to infected blood usually results from sharing needles, as in those used for illicit drugs. HIV also can be spread by sharing needles for anabolic steroids to increase muscle, tattooing, and body piercing. To prevent the spread of HIV, as well as other diseases including hepatitis, needles should never be shared. At the beginning of the HIV epidemic, many individuals acquired HIV infection from blood transfusions or blood products, such as those used for hemophiliacs. At present, however, because blood is tested for both antibodies to HIV and the actual virus before transfusion, the risk of acquiring HIV from a blood transfusion in the United States is extremely small and is considered insignificant.

There is small evidence that HIV can be transferred by casual exposure, as might occur in a household setting. For example, unless there are open sores or blood in the mouth, kissing is generally considered not to be a risk factor for transmitting HIV. This is because saliva, in contrast to genital secretions, has been shown to contain very little HIV. Still, theoretical risks are associated with the sharing of toothbrushes and shaving razors because they can cause bleeding, and blood can contain large amounts of HIV. Consequently, these items should not be shared with infected people. Similarly, without sexual exposure or direct contact with blood, there is little if any risk of HIV contagion in the workplace or classroom.

Types of treatment

There are five main groups of drugs involved:
 Nucleoside reverse transcriptase inhibitors (NRTIs)
 Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
 Nucleotide reverse transcriptase inhibitors
 Protease inhibitors
 Fusion inhibitors.
Usually, three different drugs from at least two of these groups are taken together, two to four times a day. Some tablets now contain two or three dissimilar drugs. The advantage of these combination drugs is that people do not need to take as many tablets each day.

How treatment works

When the HIV virus gets into a body cell, it normally starts to make copies of itself. These copies then spread out of that cell and into another. Drug treatments control the virus by interfering with the chemicals it uses to make copies of itself inside the body cells. The fusion inhibitors stop the HIV binding onto a new cell so it can no longer enter.
Over time, the virus can become resistant to the drugs, which means that they won’t work as well. The treatment may then have to be changed to a different combination of drugs.
People taking drug treatment for HIV will probably need to take it for the rest of their lives. Stopping drug treatment, even for little periods of time, can cause the virus to become resistant to those drugs. It is not recommended that anyone interrupt drug treatment without medical advice.
Drug treatment does not work well for everyone. Even when it is working well, it cannot control all of the virus, so the person will still have HIV in their body.
Treatment does not stop someone with HIV from being able to pass on the virus through unprotected sex or sharing needles or injecting equipment.