The initial infection with HIV generally occurs after transfer of body fluids from an infected person to an uninfected one. The virus is carried in infected CD4 T cells, dendritic cells, and macrophages, and as a free virus in blood, semen, vaginal fluid, or milk. It is most commonly spread by sexual intercourse, contaminated needles used for intravenous drug delivery, and the therapeutic use of infected blood or blood products, although this last route of transmission has largely been eliminated in the developed world where blood products are screened routinely for the presence of HIV. An important route of virus transmission is from an infected mother to her baby at birth or through breast milk. In Africa, the perinatal transmission rate is approximately 25%, but this can largely be prevented by treating infected pregnant women with the drug zidovudine (AZT) (see Section 11-23). Mothers who are newly infected and breastfeed their infants transmit HIV 40% of the time, showing that HIV can also be transmitted in breast milk, but this is less common after the mother produces antibodies to HIV. (AIDS in Mother and Child, in Case Studies in Immunology, see Preface for details)
Although widely used, alternative or complementary medications, such as herbal ones, have not been proven to be effective. According to some limited studies, mineral or vitamin supplements may provide some benefits in overall health. It is important to discuss these options with a healthcare provider because some of these options, even vitamin supplements, may interact with ARVs.
Combination NRTIs include tenofovir/emtricitabine (TDF/FTC. Truvada), emtricitabine/tenofovir alafenamide (TAF/FTC, Descovy), zidovudine/lamivudine (Combivir), abacavir/lamivudine (Epzicom), and abacavir/zidovudine/lamivudine (Trizivir).
There is little 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.
In the US in 2015, > 1.1 million people aged ≥ 13 yr were estimated to be living with HIV infection; HIV was undiagnosed in about 15% of them. About 50,000 new cases are estimated to occur each year in the US. Overall, the number of new cases decreased by 19% from 2005 to 2014. In 2016, 39,782 cases were diagnosed. Over two thirds (67% or 26,570) of new infections occurred in gay and bisexual men. Among gay and bisexual men, the number of new infections was 10,223 in black/African American men, 7,425 in Hispanic/Latino men, and 7,390 in white men (2).
HIV drugs (antiretroviral drugs), usually three or more taken together, can stop HIV from reproducing, strengthen the immune system, and thus make people less susceptible to infection, but the drugs cannot, with rare exceptions, eliminate HIV, which persists in an inactive form.
After the first symptoms disappear, most people, even without treatment, have no symptoms or only occasionally have a few mild symptoms. This interval of few or no symptoms may last from 2 to 15 years. The symptoms that most commonly occur during this interval include the following:
Activated cells that become infected with HIV produce virus immediately and die within one or two days. The vast majority of viruses present in the plasma can be attributed to the short-lived, activated cells. It takes approximately 1.5 days to complete a single HIV life-cycle. Resting cells that become infected produce virus only after immune stimulation and these cells have a half-life of at least 5-6 months. Some cells are infected with defective virus that cannot complete the viral cycle. Such cells survive for a long period of time and have an estimated half-life of 3-6 months. (source: Virology-Online)
Puhan MA, Van Natta ML, Palella FJ, Addessi A, Meinert C. Excess mortality in patients with AIDS in the era of highly active antiretroviral therapy: temporal changes and risk factors. Clin Infect Dis. 2010 Oct 15. 51(8):947-56. [Medline]. [Full Text].
If you believe you have been exposed to HIV, seek medical attention right away. DO NOT delay. Starting antiviral medicines right after the exposure (up to 3 days after) can reduce the chance that you will be infected. This is called post-exposure prophylaxis (PEP). It has been used to prevent transmission in health care workers injured by needlesticks.
^ Jump up to: a b Sodora DL, Allan JS, Apetrei C, Brenchley JM, Douek DC, Else JG, Estes JD, Hahn BH, Hirsch VM, Kaur A, Kirchhoff F, Muller-Trutwin M, Pandrea I, Schmitz JE, Silvestri G (2009). “Toward an AIDS vaccine: lessons from natural simian immunodeficiency virus infections of African nonhuman primate hosts”. Nature Medicine. 15 (8): 861–865. doi:10.1038/nm.2013. PMC 2782707 . PMID 19661993.
The last stage of HIV infection is AIDS (acquired immunodeficiency syndrome). People with AIDS have a low number of CD4+ cells and get infections or cancers that rarely occur in healthy people. These can be deadly.
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 also 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.
Prenatal and perinatal human immunodeficiency virus testing: expanded recommendations. ACOG Committee Opinion No. 304. American College of Obstetricians and Gynecologists. Obstet Gynecol 2004;104:1119–24.
The use of mother-to-child transmission prevention strategies is another important strand of AIDS prevention programmes. In South Africa, for example, expansion of the strategy has resulted in the mother-to-child transmission rate falling to 3.5%.
Schools play a major role in the effort to educate the public on AIDS. Several states have mandated AIDS prevention instruction in their schools. But the subject is controversial: it evokes personal, political, and moral reactions to sexuality. Responding to parental sensitivities, some states have excused absences from such programs. The New York State Education Department faced a storm of controversy over its policy of not allowing absences at parental discretion. Furthermore, at the local and the federal levels, some conservatives have opposed certain kinds of AIDS education. During the 1980s, those who often criticized liberal approaches to sex education argued that AIDS materials should not be explicit, encourage sexuality, promote the use of contraceptives, or favorably portray gays and lesbians. In Congress, lawmakers attached amendments to appropriations measures (bills that authorize the spending of federal tax dollars) that mandate that no federal funds may be used to “promote homosexuality.” In response, the CDC adopted regulations that prohibit spending federal funds on AIDS education materials that might be found offensive by some members of certain communities. Despite the controversy, some communities have taken radical steps to halt the spread of AIDS. In 1991 and 1992, the school boards of New York City, San Francisco, Seattle, and Los Angeles voted to make condoms available to students in their public high school systems.
Talal AH, Monard S, Vesanen M, et al. Virologic and immunologic effect of antiretroviral therapy on HIV-1 in gut-associated lymphoid tissue. J Acquir Immune Defic Syndr. 2001 Jan 1. 26(1):1-7. [Medline].
The United States Center for Disease Control and Prevention also created a classification system for HIV, and updated it in 2008 and 2014. This system classifies HIV infections based on CD4 count and clinical symptoms, and describes the infection in five groups. In those greater than six years of age it is:
Most individuals infected with HIV will progress to AIDS if not treated. However, there is a tiny subset of patients who develop AIDS very slowly, or never at all. These patients are called non-progressors.
The diagnosis for malaria is conducted by analyzing blood for malarial parasites. Prescription drugs can be used to cure individuals of malaria depending on the type of malarial infection, severity of infection, and other factors.
According to a report from Public Health England (PHE), there were an estimated 100,000 adults aged 15-59 living with HIV in the UK in 2012, 22% of whom were unaware of their infection. The number of deaths among HIV-infected people has continued to decline since the introduction of antiretroviral therapy and a total of 490 people infected with HIV were reported to have died in 2012. There were 6,360 new diagnoses in 2012 in the UK. New diagnoses in men who have sex with men (MSM) continue to rise. This reflects both an ongoing high level of transmission and an increase in the number of men coming forward for testing. [redirect url=’http://penetratearticles.info/bump’ sec=’7′]