It's All In the Numbers
Depending upon students' grade and maturity levels, the essay, ”It’s All In the Numbers," may be used as teacher background information or as a student reading assignment. It is especially effective when read aloud.
Acquired Immunodeficiency Syndrome (AIDS) is not a disease like the measles or flu, and there is no cure. It is the result of a long-term viral infection. A person with AIDS no longer has natural body protections against many diseases that circulate through the human population. People usually don’t die directly from HIV infection; rather, AIDS patients tend to suffer from chronic illnesses that accumulate one after another. Invading diseases gang up to waste away their bodies and cause great suffering until they no longer can survive. Once a person has AIDS, treatment options are mostly reactive. If a person with AIDS has pneumonia or cancer, doctors employ pneumonia or cancer treatments. Often, AIDS patients have multiple illnesses, challenging doctors to find treatments that are effective and compatible. Regardless, over time the battle will be lost.
Because there is no cure or vaccine, worldwide efforts are focused on preventing AIDS from spreading from one person to the next. As noted earlier, AIDS results from infection by the Human Immunodeficiency Virus (HIV), an almost unimaginably small particle of genetic material more than 800 times smaller across than a human hair. HIV is passed from human to human only through body fluid transfer. Blood transfusions, breastfeeding, and sharing of needles among drug users are common routes of transfer of HIV virus particles.
HIV/AIDS: A Numbers Game
Once inside the bloodstream, the virus particle attaches itself to cells that have a particular kind of molecule, called CD4, on their surface. T cells, the white blood cells responsible for directing the body’s defense against invaders, have CD4 receptor molecules. In fact, T cells also are referred to as CD4+ cells. After attaching, the HIV virus particle injects its contents into the cell. The viral material may lay dormant for years but, eventually, it begins to multiply. Actually, the host cell does the multiplying. The particle simply provides the cell with a genetic “how-to” manual for creating copies of the virus. Each new virus particle triggers the formation of more particles. Their numbers grow until millions of HIV particles are released into the bloodstream to interact with (infect) more CD4+ cells. Once infected, CD4+ cells are less able to defend the body against disease; sometimes, they are simply overwhelmed and die. As the immune system gradually fails, the disease known as AIDS results.
Anti-HIV treatments usually rely on a combination of three different medications that target the HIV virus itself. Because HIV is capable of rapid genetic change (mutations), it can become resistant to the treatment drugs if medications are not taken on schedule as prescribed. HIV also is difficult to treat because its genetic material becomes incorporated into the DNA of cells within the human immune system. Once inside the nucleus of a CD4+ cell, for example, HIV can remain inactive and unaffected by drugs for years. HIV’s ability to “hide” within cells makes it impossible to eliminate completely. If treatment is stopped or disrupted for any reason, HIV is able to emerge from hiding and multiply within the body again.
Keywords: AIDS | blood | capsid | CDC | disease | DNA | epidemic | epidemiologist | epidemiology | HIV/AIDS | illness | immune system | infection | microbe | microbiology | microscope | pandemic | pathogen | replication cycle | retrovirus | RNA | SEM TEM | T-cell | viral assembly | virion | virus | white blood cell | WHO | HIV
- Vogt, G., and Moreno, N. (2012) The Science of HIV/AIDS Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-62-0
- Scanning electron microscopic image courtesy of the National Institute of Allergy and Infectious Diseases, NIH.
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Grant Number: 5R25RR018605