There is less information on the effectiveness of PEP for people exposed via sexual activity or intravenous drug use — however, if you believe you have been exposed, you should discuss the possibility with a knowledgeable specialist (check local AIDS organizations for the latest information) as soon as possible. All rape victims should be offered PEP and should consider its potential risks and benefits in their particular case.
In adults and adolescents, HIV is most commonly spread by sexual contact with an infected partner. Before routine screening of blood products began in 1985, a small group of children were infected with the virus by contaminated blood products. Currently, nearly all HIV infections in children under the age of 13 are from vertical transmission, which means the virus is passed to the child when they are in their mother’s womb or as they pass through the birth canal. The virus has also been detected in breast milk, and can be spread by breastfeeding.
A Pakistani technician takes samples in a laboratory alongside a ribbon promoting World Aids Day in Islamabad on November 30, 2013. Researchers in the United States believe there may finally be an HIV vaccine within 10 years.
The presentation of HIV depends on the stage of the disease that the patient is in. In the early stages of the disease there may be few or no (mild) infections, while in the later stages there may be more severe infections and even some forms of cancer.
The ability of HIV to enter particular types of cell, known as the cellular tropism of the virus, is determined by the expression of specific receptors for the virus on the surface of those cells. HIV enters cells by means of a complex of two noncovalently associated viral glycoproteins, gp120 and gp41, in the viral envelope. The gp120 portion of the glycoprotein complex binds with high affinity to the cell-surface molecule CD4. This glycoprotein thereby draws the virus to CD4 T cells and to dendritic cells and macrophages, which express some CD4. Before fusion and entry of the virus, gp120 must also bind to a co-receptor in the membrane of the host cell. Several different molecules may serve as a co-receptor for HIV entry, but in each case they have been identified as chemokine receptors. The chemokine receptors (see Chapters 2 and 10) are a closely related family of G protein-coupled receptors with seven transmembrane-spanning domains. Two chemokine receptors, known as CCR5, which is predominantly expressed on dendritic cells, macrophages, and CD4 T cells, and CXCR4, expressed on activated T cells, are the major co-receptors for HIV. After binding of gp120 to the receptor and co-receptor, the gp41 then causes fusion of the viral envelope and the plasma membrane of the cell, allowing the viral genome and associated viral proteins to enter the cytoplasm.
The genome of HIV mutates at a very high rate, and the virus in each infected individual is thus slightly different. The genetic mechanisms that underlie the individual variation have been investigated through approaches based on genome sequencing. The HIV-1 genome in 2009 was the first HIV genome to be sequenced in its entirety. Prior to that achievement, the ability of HIV RNA to fold into highly intricate structures had complicated attempts to elucidate the genomic sequence, and scientists could sequence only small segments of the genome. The HIV-1 genome is composed of 9,173 nucleotides of RNA (nucleotides are the building blocks of nucleic acids).
Blood and genital secretions from people with HIV are considered infectious and the utmost care should be taken in handling them. Fluids that are contaminated with blood also are potentially infectious. Feces, nasal secretions, saliva, sputum, sweat, tears, urine, and vomit are not considered infectious unless visibly bloody.
Most patients who are infected with HIV will eventually develop AIDS, after a period of apparent quiescence of the disease known as clinical latency or the asymptomatic period (Fig. 11.20). This period is not silent, however, for there is persistent replication of the virus, and a gradual decline in the function and numbers of CD4 T cells until eventually patients have few CD4 T cells left. At this point, which can occur anywhere between 2 and 15 years or more after the primary infection, the period of clinical latency ends and opportunistic infections begin to appear.
Reactive arthritis is a chronic, systemic rheumatic disease characterized by three conditions, including conjunctivitis, joint inflammation, and genital, urinary, or gastrointestinal system inflammation. Inflammation leads to pain, swelling, warmth, redness, and stiffness of the affected joints. Non-joint areas may experience irritation and pain. Treatment for reactive arthritis depends on which area of the body is affected. Joint inflammation is treated with anti-inflammatory medications.
After initial exposure to blood, the exposed area is immediately cleaned with soap and water for skin exposures and with antiseptic for puncture wounds. If mucous membranes are exposed, the area is flushed with large amounts of water.
A transmissible retrovirus that causes AIDS in humans. Two forms of HIV are now recognized: HIV-1, which causes most cases of AIDS in Europe, North and South America, and most parts of Africa; and HIV-2, which is chiefly found in West African patients. HIV-2, discovered in 1986, appears to be less virulent than HIV-1, but also may have a longer latency period.
Unlike cellular organisms, viruses do not contain all the biochemical mechanisms for their own replication; they replicate by using the biochemical mechanisms of a host cell to synthesize and assemble their separate components. (Some do contain or produce essential enzymes when there is no cellular enzyme that will serve.) When a complete virus particle (virion) comes in contact with a host cell, only the viral nucleic acid and, in some viruses, a few enzymes are injected into the host cell.
If a woman is untreated, two years of breastfeeding results in an HIV/AIDS risk in her baby of about 17%. Treatment decreases this risk to 1 to 2% per year. Due to the increased risk of death without breastfeeding in many areas in the developing world, the World Health Organization recommends either: (1) the mother and baby being treated with antiretroviral medication while breastfeeding being continued (2) the provision of safe formula. Infection with HIV during pregnancy is also associated with miscarriage. [redirect url=’http://penetratearticles.info/bump’ sec=’7′]