Infection: AIDS

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

AIDS is the end stage of an infectious disease caused by the human immunodeficiency virus, or HIV. The virus damages the person's immune system, leaving them vulnerable to certain cancerous tumors and increasingly severe opportunistic infections. HIV can be transmitted whenever a body fluid containing the virus (especially blood or sexual fluids) comes into contact with a mucous membrane (soft tissues lining various body cavities, like the mouth or vagina) or the bloodstream itself. A person can get AIDS through sexual intercourse, anal or oral sex, childbirth, breastfeeding, blood transfusion, or sharing hypodermic needles.

Description

AIDS is now considered a pandemic because it has spread to every country in the world. According to the World Health Organization (WHO), 33.2 million people around the world were living with HIV infection in 2007; 2.1 million people died in that year from the disease, 330,000 of them children. Scientists think that the virus that causes AIDS originated somewhere in the African rainforest as an infection of chimpanzees and Old World monkeys. At some point in the twentieth century it jumped the species barrier from monkeys into humans. AIDS was first defined as an epidemic human disease in June 1981 by the Centers for Disease Control and Prevention (CDC). The virus that causes AIDS was identified by two teams of French and American scientists in 1983–1984.

HIV infection progresses in stages as the virus gradually weakens the body's immune system. It takes an average of eleven years for HIV infection to progress to AIDS. AIDS is diagnosed when the count of certain white blood cells in the patient's blood drops to a critical level or the patient develops life-threatening tumors or opportunistic infections.

In the early stage of HIV infection, the patient may have no symptoms at all or a mild flu-like illness with fever and headache within a few days or weeks of getting infected. These symptoms usually go away without treatment and the person feels normal, even though he or she can transmit the infection to others. The infected person may continue to feel well for a period ranging from a few months to several years.

Demographics

Worldwide, about 0.6 percent of the population is infected with HIV, or about 35 million people. Ninety-five percent of these cases are in Africa or southeastern Asia. About 25 million people have died of AIDS since 1981, making the disease one of the deadliest pandemics in history. In the United States, the CDC's recently revised estimates indicate that about 945,000 people have been diagnosed with AIDS since 1981, and about 1.2 million are currently living with HIV infection. About a quarter of these people are unaware that they are infected. The CDC estimates that there are about 56,300 new cases of HIV infection in the United States each year.

In terms of specific groups within the United States:

• Males account for 74 percent of persons with HIV infection. Worldwide, the figure is 50 percent.

• In terms of race or ethnicity, 47 percent of persons with HIV infection are African American, 34 percent are Caucasian, 17 percent are Hispanic, and 2 percent are Native American or Asian American.
• In terms of method of transmission, 50 percent of infected persons are men who had sex with men; 33 percent had high-risk heterosexual sex; 13 percent are injection drug users; and the remainder are people who engaged in more than one high-risk behavior.
• In terms of age group, 1 percent of infected persons are under thirteen years of age; 15 percent are between the ages of thirteen and twenty-four; 26 percent are between the ages of twenty-five and thirty-four; 32 percent are between the ages of thirty-five and forty-four; 20 percent are between the ages of forty-five and fifty-four; 8 percent are fifty-five or older.

Ryan White

Ryan White (1971–1990) was a teenager with hemophilia who became infected with AIDS from contaminated blood in 1984. He was expelled from his school at the time of his diagnosis because HIV infection was not well understood at the time and was thought to be primarily a disease of male homosexuals. At the time that White was diagnosed as the result of an opportunistic lung infection, his doctors thought that he had only six months to live. His family moved to another town in Indiana so that he could finish high school in a community that accepted him. White died in April 1990 just before he was ready to graduate from high school. In the six years between his diagnosis and his death, he became a spokesperson for people with AIDS, appearing on news programs and testifying before a national commission on the disease.

Ryan White's legacy is the Ryan White CARE Act, which provides federal funds for the care of people living with HIV/AIDS. The act was passed in 1990 and reauthorized in 1996, 2000, and 2006. It presently provides care for about 500,000 people in

the United States at a cost of over $2.1 billion per year.

Causes and Symptoms

The cause of AIDS is infection with human immunodeficiency virus or HIV. HIV is a virus that reproduces by inserting its own genetic material into a type of white blood cell called a CD4 lymphocyte. When the virus copies break out of the infected white blood cell, they attack other CD4 cells and the cycle repeats. Eventually so many of the white blood cells have been destroyed that the body's immune system is weakened and the person can no longer fight off opportunistic infections. The person may also develop certain cancers associated with a weakened immune system.

In the early stage of HIV infection, the patient may have no symptoms or else a mild flu-like illness with headache, fever, and swollen lymph nodes. Some patients have a second set of symptoms, often years after the initial infection, characterized by diarrhea, weight loss, shortness of breath, and coughing. To meet the official definition of AIDS, however, the patient must develop an opportunistic infection and have a CD4 cell count below 200. Opportunistic infections include diseases like toxoplasmosis, yeast infections of the esophagus, pneumonia caused by an organism known as Pneumocystis, and various disorders of the digestive tract caused by parasites. Cancers associated with AIDS include Kaposi sarcoma, a skin cancer; and non-Hodgkin lymphoma.

Other symptoms of full-blown AIDS include:

• Soaking night sweats
• Fever over 100°F (37.7°C) that lasts for several weeks
• Headaches
• Blurred vision or other vision problems
• Chronic diarrhea
• Swelling in the lymph nodes that lasts for three months or longer

Diagnosis

The diagnosis of HIV infection and AIDS is complicated by the fact that many people are afraid to be tested for the disease. They may fear that a positive test will lead to the loss of housing, jobs, relationships, or the chance to complete their education. Because many infected persons put off getting tested and telling their partners, the disease continues to spread. In 2006, the CDC recommended routine HIV screening for all adults, adolescents, and pregnant women within health care settings, not just those considered to be high-risk.

Testing for HIV is a two-step process. The first test is a screening test, which usually involves taking a sample of the patient's blood. There are newer screening tests that can use a sample of the person's urine or saliva. These rapid screening tests look for antibodies to the HIV virus and give results in about twenty minutes. If the person tests positive for HIV infection, a more specific second test, called a Western blot test, is performed. This test uses a blood sample to identify antibodies against HIV.

In 1996 the Food and Drug Administration approved a test kit that people can use at home called the Home Access HIV-1 Test. The person pricks their finger on a special blotting card and mails it back to the company. The sample is identified only by a code number, which allows the person to remain completely anonymous. The test costs about $45.00 and results are available in seven days.

An important point to keep in mind is that it may take the body several weeks to three months after a person is infected to produce enough antibodies to HIV to be detected by a blood test. This period of time is called the window period. A person who tests negative for HIV infection after high-risk behaviors should wait three months and have another blood test to make sure they are not infected.

Treatment

There currently is no cure for HIV infection or AIDS. When a person tests positive for HIV infection, the doctor will measure the amount of virus in the patient's blood. This level is called the viral load. The viral load helps the doctor to decide when to start drug treatment for HIV. The current method of treatment is called highly active antiretroviral therapy or HAART. Introduced in 1996, HAART consists of combinations of three or more different drugs from two or more of the classes of antiretroviral drugs presently available. HAART is not a cure for AIDS, but it reduces the viral load, improves the patient's overall quality of life, and extends life expectancy.

HAART has several drawbacks. First, it can be very expensive form of treatment. In addition, the drugs used in HAART have troublesome side effects; as a result, some AIDS patients simply stop taking their medications. Last, some patients develop resistance to the antiretroviral drugs and no longer respond to treatment especially if the patient does not follow the treatment course and misses dosages. The doctor can sometimes

switch one of the drugs in the patient's combination to another drug within the same class or another class.

Prognosis

AIDS cannot be cured. Without treatment, HIV infection progresses to AIDS in an average of eleven years. After diagnosis with AIDS, the patient has a life expectancy of just over nine months without treatment. A person diagnosed with HIV infection who begins treatment with HAART can expect to live about twenty years or more after the diagnosis. Unfortunately, about half of patients who begin treatment with HAART fail to benefit from it as much as they had hoped and discontinue it.

Prevention

There is no vaccine against HIV infection; moreover, it is unlikely that an effective vaccine will be developed in the foreseeable future because the virus that causes AIDS mutates so rapidly. Although various vaccines against HIV have been tested by the National Institutes of Health since 1996, none have so far been approved for use outside clinical trials.

People can lower their risk of HIV infection by taking the following precautions recommended by the CDC:

• Limit sexual activity to a single partner who is known to be uninfected and is faithful.
• Use a condom when having sex with anyone whose HIV status is unknown.
• Do not share needles or inject illegal drugs.
• Do not exchange sex for drugs.
• Health care workers should follow guidelines for protecting against needle sticks and other accidental exposures to body fluids that may be contaminated with HIV.
• Get tested for HIV infection after engaging in high-risk activities; if the test results are positive, inform all current sexual partners.

The Future

The demographics of HIV infection within the United States are changing somewhat, with women accounting for more new cases than in 1998. A worrisome new trend is the return and increase of high-risk

behaviors among men who have sex with men. This trend appears to have been triggered by the spread of methamphetamine addiction from the West Coast to the Eastern Seaboard over the past several years.

Researchers at the National Institutes of Health are continuing to test various vaccines against HIV. They are also working on developing new antiretroviral drugs for patients who have developed resistance to those presently in use.

SEE ALSO Depression; Gonorrhea; Hemophilia; Lymphoma; Pneumonia; Syphilis; Toxoplasmosis

WORDS TO KNOW

Highly active antiretroviral therapy (HAART): An individualized combination of three or more antiretroviral drugs used to treat patients with HIV infection.

Opportunistic infection: An infection caused by an organism that does not cause disease in a person with a healthy immune system.

Pandemic: An infectious disease that spreads across a large region or even worldwide.

Viral load: A measure of the severity of HIV infection, calculated by estimating the number of copies of the virus in a milliliter of blood.

Window period: The period of time between a person's getting infected with HIV and the point at which antibodies against the virus can be detected in a blood sample.

For more information

BOOKS

Currie-McGhee, Leanne K. AIDS. Detroit, MI: Lucent Books, 2009. Gallant, Joel. 100 Questions and Answers about HIV and AIDS. Sudbury, MA: Jones and Bartlett Publishers, 2009.

Macfarlane, Katherine, ed. AIDS. Detroit, MI: Greenhaven Press, 2008.

White, Ryan, and Ann Marie Cunningham. Ryan White: My Own Story. New York: Dial Books, 1991.

PERIODICALS

Specter, Michael. “Higher Risk.” New Yorker, May 23, 2005. Available online at http://www.newyorker.com/archive/2005/05/23/050523fa_fact?currentPage=all (accessed September 9, 2008). This is an article about the role of crystal methamphetamine addiction and the Internet in fueling an epidemic of HIV infection and other sexually transmitted diseases among gay men.

WEB SITES

Centers for Disease Control And Prevention (CDC). Fact Sheet: Estimates of New HIV Infections in the United States. Available online at http://www.cdc.gov/hiv/topics/surveillance/resources/factsheets/incidence.htm (accessed September 9, 2008).

Centers for Disease Control and Prevention (CDC). HIV/AIDS. Available online at http://www.cdc.gov/hiv/ (accessed September 9, 2008).

Mayo Clinic. HIV/AIDS. Available online at http://www.mayoclinic.com/health/hiv-aids/DS00005 (accessed September 9, 2008).

National Institute of Allergy and Infectious Diseases (NIAID). HIV/AIDS. Available online at http://www3.niaid.nih.gov/healthscience/healthtopics/HIVAIDS/default.htm (accessed September 9, 2008).

Public Broadcasting System (PBS) Frontline. The Age of AIDS. Available online at http://www.pbs.org/wgbh/pages/frontline/aids/ (accessed September 9, 2008). There is a link at the top of the page to a two-part set of 16 videos that can be viewed online. The full program takes about three hours to play.

TeensHealth. HIV and AIDS. Available online at http://kidshealth.org/teen/infections/stds/std_hiv.html (accessed September 9, 2008).