AIDS (Acquired Immune Deficiency Syndrome)
From Encyclopedia of Sex and Sexuality
The magnitude of human suffering and death caused by AIDS has made it the plague of the last decades of the twentieth century. By the beginning of 1992 the two known AIDS viruses had infected more than an estimated 13 million individuals worldwide: 1 to 1.5 million in the United States, 10 million in Africa, and 2 million in Asia, and the viruses are still spreading. At present there is no vaccine or cure for AIDS.
AIDS is caused by one of two human immunodeficiency-deficiency viruses (HIV). These viruses, identified by the abbreviations HIV–1 and HIV–2, cause disease by infecting and destroying blood cells called lymphocytes that protect the body against infection by a variety of bacterial, viral, and parasitic microorganisms (microbes), many of which are encountered daily during the normal course of living.
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[edit] History of the Disease
The origin of the HIV viruses is unknown, but much scientific information suggests that they originated in Central Africa. Tests for the HIV–1 virus done on blood specimens collected in northern Zaire in 1976 established that this virus was present in a small number of persons who had spent most or all of their lives in a remote, rural area there. Tests of blood taken from African green monkeys from the same geographic region led to the isolation of a virus (SIV–1 or simian immunodeficiency virus) closely related to the human HIV–2 virus. A mutation of SIV–1 or related viruses is the probable origin of HIV–1. This conjectural evidence does not, however, prove the African origin of HIV–1.
In 1981 the first cases of AIDS in the United States were recognized by physicians in Los Angeles. They found among homosexual men an unusual type of pneumonia caused by the microbe Pneumocystis carinii. This microbe causes illness only when the immune system has been severely weakened by drugs or disease, and is known as an “opportunistic” pathogen. Investigations of these and subsequent cases determined that HIV could be transmitted during sexual contact or through blood, either by transfusion of blood or blood products containing the virus, or by sharing injection needles and syringes contaminated with HIV-infected blood. Most AIDS cases in North America, Europe, and Africa are caused by the HIV–1 virus. HIV–2 occurs mainly in West Africa and destroys lymphocytes at a slower rate than HIV–1. The United States Centers for Disease Control and Prevention (CDC) reported in March 1994 that as of 30 September 1993, there were 339,250 reported cases of AIDS and 204,290 deaths from the disease in the United States. In 1993 103,500 new cases of AIDS were reported, although 46 percent of this increase can be attributed to a broader definition of the disease, adopted by the CDC in 1993. The report is the first in four years to contain information on heterosexual infection with AIDS. Of the new cases reported, 6,056 women and 3,232 men were infected. About half of these cases were attributed to sexual intercourse with an HIV-infected partner; 42 percent resulted from intercourse with an infected intravenous drug user.
[edit] Diagnosis of Infection
The HIV–1 virus was first isolated from AIDS patients in a laboratory culture in 1983 by research laboratories in the United States and France. Because culturing the virus is so expensive and time consuming, HIV infection is diagnosed with tests to detect HIV antibodies in the blood. These antibodies usually appear in the bloodstream three to eight weeks after infection and remain positive throughout the course of the infection. Other tests can detect the HIV virus in the blood a few days after infection but these are impractical for routine use. Thus, there is a “window” of time after becoming infected with an HIV virus when a person can have a negative antibody blood test but be able to pass the virus to their partner(s) and to those sharing injection syringes and needles.
[edit] What the Virus Does
The mechanisms by which the HIV viruses infect and attack the body are similar: they circulate in the bloodstream within infected cells and plasma. The amount of virus present in the body increases with the destruction of HIV-infected lymphocytes, especially those known as CD4 lymphocytes, which play a critical role in the recognition and destruction of invading microbes. The course of HIV infection is divided into an early viremic stage; a middle stage, where there are few symptoms or signs of disease; and a late symptomatic stage, when other viral, bacterial, and parasitic infections occur.
In the early stage following infection, HIV may produce symptoms resembling those of infectious mononucleosis. This is followed by a variable period of several years, during which few symptoms are present except for persistently enlarged lymph glands. Infected persons usually develop illnesses from microbes they have previously been infected with and from which they have recovered. These “opportunistic” microbes may be normally present on the skin, in the air, or in food. When these opportunistic infections occur, the diagnosis of AIDS is made. Most frequent in the West is Pneumocystis carinii, a protozoan parasite that causes an incapacitating and frequently fatal pneumonia in the later stages of HIV infection. Other common opportunists are Toxoplasma gondii, that invades the brain, and herpes and cytomegaloviruses, that infect the brain, eyes, and lungs. In Africa and Asia the most frequent opportunistic microbe is Mycobacterium tuberculosis. Several of these infections can generally be prevented if certain drugs are taken prophylactically.
[edit] Spreading AIDS
Although AIDS can be acquired by transfusion or injection of blood or blood products contaminated with the HIV virus, the vast majority of AIDS cases in North America, Africa, and Europe have been acquired by homosexual or heterosexual intercourse or by sharing injection needles and syringes among drug addicts. Blood and semen are likely to be infectious at any time after infection, but other body fluids such as saliva and breast milk are also infectious, especially in the very early and late stages of the infection. Sexual transmission of HIV–1 may be facilitated by the presence of genital lesions caused by syphilis, herpes, chlamydia, and trichomoniasis. Lesions on the genitals provide an opening in the skin or genital membranes by which HIV–1 escapes from the infected person and enters the uninfected partner during sexual contact. Injury to the lining membranes of the rectum during anal intercourse can also provide an opening for the HIV virus.
[edit] Course of Illness
In the United States the median life expectancy after being infected by HIV–1 is about twelve years. It is shorter in those infected by transfusions of blood or blood products and in persons who lack access to good medical care. Treatment with the antiviral drugs zidovudine, also called azidothimidine (AZT), dideoxyinosine (DDI), or dideoxycytodine (DDC), together with drugs to prevent infection by Pneumocystis carinii and herpes viruses improves the quality of life and may extend it.
The rate of progression of HIV is directly related to the rate at which the virus destroys the blood lymphocytes that defend the body against infection by microbes. The rate of HIV–2 disease progression is slower than HIV–1. It appears that a good mental and physical state of health may affect both longevity and the quality of life after the diagnosis of HIV infection. It is important to avoid emotional stress and strenuous physical exercises, eat a well-balanced diet, abstain from illicit drug use, and be seen at regular intervals by medical personnel experienced in the care of HIV-infected persons. Most urban centers in North America have support groups for persons with HIV infection and AIDS. Studies of HIV-infected American soldiers and sailors have shown that many have been able to continue working even when most of their CD4 lymphocytes have been destroyed.
[edit] Newborn Infants with AIDS
According to the CDC, between 6,000 and 7,000 HIV-infected women give birth each year. Between 25 and 30 percent of their children will be infected, about 25 percent of HIV-babies will develop AIDS in their first year of life, and 50 percent will develop AIDS by the age of three. In February 1994 American health officials announced that treating pregnant women with AZT drastically reduces the chances of their passing the disease to their children.
[edit] Prevention of the Disease
In the absence of curative therapy or a vaccine, the only way to avoid becoming infected is to avoid risk behavior. The only certain way to avoid contracting the HIV virus sexually is to be celibate or monogamous with an uninfected partner. The use of male condoms provides considerable, but not absolute, protection, as may female condoms. The latter may provide added protection when used together with male condoms but, when used alone, they are not sufficient to prevent HIV infection. Condoms must be put on the penis before beginning any oral or insertive sexual contact and should be withdrawn from an erect penis after ejaculation to prevent leakage of semen. Oil-based lubricants should not be applied to condoms as they may cause them to break open. Condoms may be coated with spermatocidal substances also used for birth control and that contain the chemical nonoxyl 9. This compound also kills HIV–1 and HIV–2, but its effectiveness as the only protection against HIV viruses has not been determined. Experience has shown that a high percentage of HIV-infected persons will, over time, infect their sexual partner(s) if they continue to have unprotected sexual intercourse.
[edit] Treatment
At the present time, there is no vaccine that protects against AIDS, nor is there a cure. Several vaccines for AIDS are under development. One, containing a genetically engineered protein (gp160) present on the surface of HIV–1, has been injected into persons already infected with the virus. This form of immune therapy slowed the rate of destruction of lymphocytes by HIV–1 and may soon be tested as a vaccine for uninfected persons.
AZT has been used to treat health care personnel who have stuck or cut themselves with needles or instruments that were contaminated by blood from HIV–1 patients. It is not clear whether this prophylactic treatment prevents infection. There is some evidence that AZT, given early in the course of the infection, may prolong the life of a patient.
