Causes
HIV causes AIDS. The virus enters immune cells, especially CD4 T-helper cells. Dormancy in those cells is possible, and activation of the virus to the replicative stage leads to the destruction of those immune cells. AIDS results when the infected person’s T-helper cell count is reduced to the extent that frequent opportunistic infections occur.
Risk Factors
Drug abuse makes addicts vulnerable to infection. The sharing of needles and cocaine straws, for example, exposes users to each other’s body fluids. Also, intravenous drug abusers inject substances with immunosuppressive effects.
Immunologic defenses also are compromised by the simultaneous abuse of alcohol and tobacco and by personal neglect. The addict also may have impaired functioning of phagocytosis, reduced superoxide production, and reduced T-cell function, making the immune system ineffective at neutralizing the virus.
Also a risk factor for HIV infection is engaging in unprotected sex. Anal and vaginal penetration that causes injury can make a person vulnerable to HIV infection.
Symptoms
The symptoms of HIV infection can be limited to the presence of anti-HIV antibodies. After the reduction of T-helper cell count, otherwise rare cancers, such as Kaposi’s sarcoma, may result. Numerous bacteria, viruses, and fungi cause infection when the immune system is compromised by a reduced count of T-helper cells.
Screening and Diagnosis
Four rapid HIV tests are available. Each has received marketing approval by the US Food and Drug Administration. These tests are OraQuick Advance Rapid HIV-1/2 Antibody Test, manufactured by OraSure Technologies; Reveal G2 Rapid HIV-1 Antibody Test by MedMira; Uni-Gold Recombigen HIV Test, made by Trinity BioTech; and Multispot HIV-1/HIV-2 Rapid Test by Bio-Rad Laboratories. Each of these tests is an HIV enzyme immunoassay (EIA), and each is considered a screening test. Also, each test mandates additional confirmatory tests if the results are positive.
The basis of these tests is the ability to detect anti-HIV antibodies in body fluids. Antibodies are products of the immune system that are produced in response to exposure to a virus and its component proteins. Antigens, or proteins, from the virus are embedded in or affixed to a filter. Because antibodies generated after exposure to HIV bind specifically to the viral proteins, antibodies in a person’s body fluids will bind to the filter exactly where the protein in the test kit was placed. To determine if antibodies from the sample are present on the filter, a second antibody from the test kit is added.
The secondary antibody specifically binds to the person’s antibodies. When an exposed person takes the test, the secondary antibody binds and creates a complex. The complex is created only when the person has anti-HIV antibodies in his or her fluids.
Detection of the complex on the filter paper is possible because the secondary antibodies in the test kit come with an enzyme linked to them. This enzyme catalyzes a reaction that results in a color change. The color is detected by visual inspection of the filter paper. Because these kits detect the presence of antibody in the person’s fluids and not the virus, a positive result requires additional testing.
The polymerase chain reaction works by detecting the genetic material unique to the HIV virus. This assay works by adding the necessary components for the replication of genetic material to the sample. If HIV genetic material is present, it will be multiplied to generate quantities that can be detected by a color-forming reaction not unlike the EIA tests.
Treatment and Therapy
Highly active antiretroviral therapy (HAART) is the recommended treatment for HIV. HAART is administered as a combination of three or more anti-HIV medications from a minimum of two different classes. Nucleoside reverse transcriptase inhibitors comprise one class of anti-HIV drug. These drugs inhibit the HIV enzyme reverse transcriptase by means of blockage with a nucleoside. Non-nucleoside reverse transcriptase inhibitors inhibit the same viral enzyme through means other than the addition of nucleosides. Protease inhibitors block another key enzyme from the virus.
Three additional classes of anti-HIV drugs block functions critical to the infection process. They are entry inhibitors, fusion inhibitors, and integrase inhibitors. Because each class of medications blocks the virus in a different way, the combination of several medications increases the chances of preventing viral replication and decreases the chance that the virus will survive long enough to mutate into a resistant form. Some of the drugs are available as a combination pill of two or more different anti-HIV medications from one or more classes.
Prevention
Prevention of HIV infection and the development of AIDS in the drug abuser centers on behavior modification. Because HIV is a blood-borne pathogen, one should not share needles. The virus also can be transmitted through sharing cocaine straws among users with damaged nasal mucosa.
Sexual activity also can expose participants to body fluids and, thus, the virus. The use of condoms is recommended. The close association of drug abuse and prostitution makes prevention difficult. Despite numerous vaccination strategies tested for the prevention of AIDS or reduction of replication of the HIV virus, no effective vaccine has been found as of 2015.
Bibliography
Levine, Donald P., and Jack D. Sobel, eds. Infections in Intravenous Drug Abusers. New York: Oxford UP, 1999. Print.
Ruiz, Pedro, Eric C. Strain, and John G. Langrod. “HIV Infections and AIDS.” The Substance Abuse Handbook. Philadelphia: Wolters, 2007. Print.
Tortora, Gerard J., Berdell R. Funke, and Christine L. Case. Microbiology: An Introduction. 11th ed. New York: Pearson, 2012. Print.
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