AIDS is an infectious disorder that suppresses the normal function of the immune system. It is caused by the human immunodeficiency virus (HIV), which destroys the body's ability to fight infections. Specific cells of the immune system that are responsible for the proper response to infections (T cells) are destroyed by this virus. Characteristically a person infected with HIV initially experiences no symptoms for a variable period of time. This may be followed by the development of persistent generalized swelling of the lymph nodes (AIDS-related lymphadenopathy). Eventually most patients infected with HIV experience a syndrome of symptoms that includes excessive fatigue, weight loss, and/or skin rashes.
The later stages of HIV infection are characterized by the progressive depression of T cells and repeated infections that can even occur during a course of antibiotic therapy for another infection (superinfections). People with AIDS are particularly vulnerable to "opportunistic infections" from bacteria that other people normally fight off. Pneumocystis carinii, which causes severe inflammation of the lungs (pneumonia), is a common infection that affects people with AIDS. Cancers (malignant neoplasms), and a wide variety of neurological abnormalities, most notably the AIDS dementia complex, may also occur. These neurological symptoms when of HIV, infects the nervous system.
AIDS (Acquired Immune Deficiency Syndrome) is a result of infection by the human immunodeficiency virus (HIV) that can be acquired years before symptoms of immunodeficiency appear. Usually there are no symptoms at the time the infection is acquired, but in some patients an acute “mononucleosis-like” illness can be identified a few weeks after exposure to HIV. Symptoms may include profound weakness and swollen glands, particularly those in the neck.
Many individuals infected with HIV experience a long period of time without any symptoms; the length of time varies greatly among patients. Approximately 10 years from exposure to the virus, 50 percent of people infected with HIV have developed some symptoms, although only a third experiences all the symptoms of immune suppression. Some people infected with HIV develop persistent generalized swelling of the lymph glands (lymphadenopathy) without any other evidence of an infection, or contract infectious diseases during antibiotic therapy for another infection (super-infection). Later, a set of symptoms develops which may include muscle wasting, fatigue, fever, thrush (oral candidiasis), and/or skin rashes. Some researchers who are studying AIDS believe that these symptoms represent the onset of AIDS, but others believe this set of symptoms is AIDS-related complex (ARC).
Often the person with HIV infection contracts an infection occurring during the course of antibiotic therapy for another infection (super-infection). This is caused by an organism that normally does not cause illness (nonpathogenic) in a person who has a normal immune system. These “opportunistic infections” affect people with AIDS because their resistance is low due to suppression of the immune system; they are often unusually susceptible to Candida and Tuberculosis. (For more information on these disorders, choose “Candidiasis” and “Tuberculosis” as your search terms in the Rare Disease Database.)
Abnormally low levels of circulating platelets in the blood (thrombocytopenia) are common in people with AIDS. HIV infection may initially be suspected with the onset of Idiopathic Thrombocytopenic Purpura which is characterized by low platelet counts, small red spots on the skin (petechiae), and profound weakness. (For more information on this disorder, choose “Idiopathic Thrombocytopenic Purpura” as your search term in the Rare Disease Database.)
Advanced stages of AIDS are characterized by super-infections, abnormal growth of malignant cells (neoplasms), and neurological abnormalities. Super-infection, the hallmark symptom of AIDS, is the result of the progressive destruction of specialized cells of the immune system (T4 helper cells). An individual who has advanced AIDS faces life-threatening infections from a variety of different disease-causing organisms (pathogens), particularly the bacteria Pneumocystis carinii. These infections are frequently difficult to treat and may be impossible to eliminate. Recurrences of these infections occur often and may be due to viral, bacterial, fungal, and/or single-celled organisms (protozoa).
Viruses that may infect people with AIDS include cytomegalovirus (CMV), herpes simplex virus (types I and II), Epstein-Barr virus, varicella zoster and/or papovavirus. Bacteria that may cause infection include Mycobacterium tuberculosis, Mycobacterium avium-intracellulare, Legionella pneumophila, Klebsiella pneumoniae, and different varieties of Salmonella. Fungus infections may be caused by Candida albicans, Cryptococcus neoformans, Histoplasma capsulatum, and/or a variety of Aspergillus fungi.
Single-celled organisms (protozoa) that may infect individuals with AIDS include Pneumocystis carinii, Toxoplasma gondii, Entamoeba histolytica, Giardia lamblia, Cryptosporidium, and/or Isospora belli. (For more information on these disorders, choose “Cytomegalovirus Infection,” “Varicella Zoster,” “Tuberculosis, “Legionnaire’s,” “Candidiasis,” “Cryptococcosis,” “Aspergillosis,” “Interstitial Pneumonia,” and “Giardiasis” as your search terms in the Rare Disease Database.)
The most common opportunistic infection in people with AIDS is a form of interstitial pneumonia known as Pneumocystis carinii pneumonia. This form of pneumonia is characterized by high fevers and difficulty breathing (dyspnea). These symptoms typically develop gradually over a period of several weeks. Also very common in people with AIDS is Cytomegalovirus infection (CMV) which may result in inflammation of the mucosal lining of the small intestine (enteritis) and inflammation of the delicate membrane of the eyes (retinitis). People with AIDS are also vulnerable to tuberculosis. Infections of the central nervous system may include inflammation of the membranes that surround the brain and spinal cord (cryptococcal meningitis), and parasitic infection of the brain (Toxoplasmosis), which usually causes jerky movements of the hands, face and/or feet. Convulsions (focal seizures) may also occur. Examination of the brain by CT scan may reveal an area of the brain that is scarred by the invading parasites.
Cancerous growths (malignant neoplasms) also occur in some people with AIDS. A specific type of cancer known as Kaposi’s sarcoma is especially common in homosexuals with AIDS, occurring in as many as 37 percent of these patients. It is much less frequent in heterosexuals with AIDS for reasons that are not clear. Kaposi’s Sarcoma is a cancer that generally affects the skin, but may also affect the internal organs of the body. People with this type of cancer develop small purple areas on the skin; raised hardened areas (nodules) may also appear that represent tumors of the blood vessels (vascular system). People with AIDS who have only Kaposi’s Sarcoma may have a somewhat better prognosis than those individuals who also experience repeated infections. This may be because people with AIDS who have only Kaposi’s Sarcoma may have immune function that is slightly better up to that point.
Researchers believe that Kaposi’s Sarcoma may be caused by an infectious virus of the herpes family, and it may be transmitted through sexual contact. Although many people with AIDS get Kaposi’s sarcoma, it also occurs in people who are not HIV positive. Scientists have isolated the herpes-like virus in tumors of people with Kaposi’s sarcoma even though they are HIV negative. More research is needed to confirm these findings. Other cancers that may be associated with AIDS include certain malignant lymphomas (e.g., Hodgkin’s lymphoma) and primary tumors of the brain (B cell lymphomas).
The most devastating neurological complication of AIDS is the progressive degeneration of brain tissue (HIV encephalopathy), also known as AIDS-Related Dementia Complex. Research suggests that as many as 60 percent of AIDS patients develop a profound loss of mental capabilities (dementia) that cannot be associated with super-infection. Other neurological complications of AIDS may include the impaired ability to coordinate movement (ataxia), loss of motor function and feeling in the legs accompanied by jerky muscle contractions (spastic paraplegia), and/or progressive disease of the nerves in the arms and legs (peripheral neuropathy).
Peripheral neuropathy may affect 10 percent or more of people with AIDS, but the symptoms and the causes vary greatly among individuals. The variety of symptoms caused by disease within the nerves outside the brain (peripheral nervous system) includes sensory and motor neuropathy, and multiple mononeuropathy (degeneration of one nerve). (For more information on this disorder, choose “Peripheral Neuropathy” as your search term in the Rare Disease Database.)
Developmental abnormalities occur in children with AIDS and are characterized by the progressive loss of cognitive ability as the disease progresses. An AIDS-associated dysmorphic syndrome in children, the result of HIV infection in the fetus, has also been identified. (For more information on this disorder, choose “AIDS Dysmorphic Syndrome” as your search term in the Rare Disease Database).
AIDS is an infectious disease caused by the human T cell lymphotrophic virus (originally called HTLV-III) which is now known as HIV (human immunodeficiency virus). This retrovirus, which is covered by a fatty protein (“enveloped”), attacks the essential proteins in the core of the cell (RNA) and eventually becomes part of the cell. The two most common human immunodeficiency viruses are HIV-1 and HIV-2. HIV-1 causes the vast majority of AIDS cases worldwide. HIV-2 occurs in West Africa and may be weaker than the HIV-1 virus.
There are 3 major routes of transmission of HIV: sexual contact, blood-borne transmission, and infection of a developing fetus by an infected mother (perinatal transmission). Worldwide, sexual contact is the most common method of transmission. In the United States, sexual contact accounts for most of the spread of disease among the male homosexual population and heterosexual transmission occurs most often from intravenous drug addicts. In central Africa, sexual transmission occurs primarily in heterosexuals.
The next most common means of the worldwide spread of AIDS is blood-borne. This includes transfusions of blood and blood products that are not adequately screened for HIV, accidental needlesticks with contaminated hypodermic syringes and other occupational accidents among health care workers, and intravenous drug abusers who share contaminated needles. Blood screening for the HIV antibody, which began in 1985, has drastically reduced the risk of getting AIDS through blood and plasma transfusions and products manufactured from blood components.
HIV-infected mothers may transmit HIV to their unborn child. A newborn may also be infected during the process of delivery (perinatal) or through breast milk. Most pediatric AIDS cases result from perinatal transmission, the mothers being intravenous drug abusers or sexual partners of drug abusers. The risk of the child acquiring HIV infection by this means is estimated to be about 30 to 40 percent. However, in recent years it has been learned that HIV transmission to newborns may be prevented if the pregnant women is given HIV medications.
In young children, the incubation period of HIV infection is much shorter than in adults. Most children develop symptoms of AIDS within 2 years. Similarly, women tend to progress to AIDS more quickly than males.
About 55 percent of the homosexual population in certain communities in the United States; have been found to have antibodies to HIV. This suggests that although exposure to the virus has been widespread, another factor may be necessary for HIV infection to fully develop. Infection with other organisms along with HIV may be a factor in the transmission of HIV.
It is now known that HIV is a virus that initially affected African monkeys and the virus jumped from monkeys to humans. Monkeys with HIV infection show no symptoms (asymptomatic) but the virus can be deadly to humans.
Several different groups of people are particularly at risk for infection by HIV resulting in AIDS. The 2 major groups at risk include homosexuals and intravenous drug abusers. Other groups at risk for HIV infection include people who received blood transfusions and/or blood products, (including hemophiliacs), before blood was routinely screened for HIV. The risk of new infection by the HIV virus through blood transfusions has been dramatically reduced since the beginning of testing to detect the presence of the HIV virus in donated blood and blood products. Sexual partners and children born to individuals in high-risk groups are also at increased risk for getting HIV infection.
Kaposi’s sarcoma, immunologic evidence of infection with HIV, and AIDS-like syndromes are exceptionally common among both sexes in central Africa where the disease is thought to have originated. The major route of transmission in central Africa is sexual contact between heterosexuals (partners of the opposite sex).
In the United States, transmission of AIDS through heterosexual intercourse is a growing problem. Intravenous drug addicts and their sexual partners are the primary sources of AIDS infection among heterosexuals. Four out of 5 cases reported among this group are women.
Some studies find variable rates of transmission through sexual intercourse depending on how the first partner became infected. One study found that drug abusers were much more effective transmitters of HIV than people infected through contaminated blood products. In addition, rates of infection may vary among individuals or in the same person over time. Available evidence suggests that the likelihood of HIV transmission in a single heterosexual encounter may be less than 1 percent. The virus probably spreads more easily during anal intercourse, which more often involves tearing of tissue and the entry of HIV directly into the bloodstream. Having multiple sexual partners, whose carrier status is not known, also increases risk of HIV infection.
There is currently a worldwide epidemic of HIV infection. In the United States, over 1 million people are thought to be infected with the HIV virus that causes, with most cases in the larger cities AIDS. The larger major cities in this country have reported the highest rates of HIV infection. AIDS cannot be regarded as an infectious disease restricted to certain populations or certain geographic areas. The virus can affect anyone, anywhere they live.
The diagnosis of HIV infection and AIDS usually begins with a blood test (enzyme-linked immunosorbent assay [ELISA]) that detects the presence of antibodies to HIV. Because this test has a moderately high rate of positive results that are actually negative (false-positive results), any positive test should be repeated and confirmed by a more sophisticated test known as the western blot test. This test detects the presence of specific antibodies to HIV.
The ELISA and western blot tests will not detect cases of HIV infection when the antibody to HIV is either absent or undetectable. This may occur in the first few months following HIV infection. Cases of AIDS have been reported in which antibodies to HIV takes months or years to develop in infected individuals. Detection of these cases of HIV infection requires a test for the virus itself. Many people are advised to take the ELISA and western blot test months apart in order to rule out the presence of HIV infection after any contact that placed them at risk for AIDS.
The diagnosis of AIDS, as opposed to HIV infection, is based on documented HIV infection and the presence of a set of symptoms or syndromes including opportunistic infection, neoplasm, and/or neurological disease.
Treatment of HIV infection involves the use of several drugs together (the HIV "cocktail").
The treatment of choice for AIDS Zidovudine (also known as Retrovir or AZT) is a basic drug currently used for people infected with HIV, whether they have symptoms or not. AZT ma. slow the progression of HIV by inhibiting production of an essential enzyme necessary for the AIDS virus to reproduce itself. AZT has been approved by the Food and Drug Administration for the treatment of children as young as six months of age who have HIV or AIDS.
Other drugs known as nucleoside analogues are used in combination with AZT, as well as
Many infections associated with AIDS respond to antibiotics, antifungals, etc.. although recurrences are very common. Nystatin, clotrimazole, and ketoconazole have controlled episodes of esophageal and oral candidiasis. Severe candidiasis, as well as cryptococcal meningitis, and other major infections related to AIDS, usually respond to amphotericin B or fluconazole. 5-Fluorocytosine may be used in combination with amphotericin in cryptococcal disease. Herpes simplex has responded to a course of treatment with acyclovir. Toxoplasmosis may be controlled in some cases with sulfadiazine and pyrimethamine, although these drugs have side effects that suppress the immune system and thus may render the patient more vulnerable than ever to opportunistic infections. The antibiotic Biaxin is being used to treat Myobacterium avium complex infections.
Cryptosporidiosis may be treated symptomatically with tincture of opium, diphenoxylate, or cholestyramine. A combination of quinine and clindamycin has also been reported to be effective in the treatment of crytosporidiosis.
Pneumocystis carinii pneumonia is treated with the drugs, trimethoprim-sulfamethoxazole and pentamidine. Pentamidine in aerosol form is another use for prevention (prophylaxis) against Pneumocystis carinii infection. Patients with very low CD4+ cell counts (under 200 cells per microliter), as well as patients who have had one episode of P. carinii pneumonia, are recommended to receive monthly aerosolized pentamidine (NebuPent) treatment to prevent this form of pneumonia. The antibiotics Septra, Bactrim and Mephon may also be used to treat Pneumocystis Carninii Pneumonia.
Treatment is available for other kinds of AIDS-related infections. These include Mycobacterium avium-intracellulare, and Cytomegalovirus infection. The drug ganciclovir (dihydroxypropoxymethyl guanine DHPG) may be effective against inflammation of the retina of the eyes caused by Cytomegalovirus infection. This treatment may prevent blindness. AIDS wasting is treated with steroids, human growth hormone (Serostim) or Thalidomide.
Kaposi's sarcoma, as well as other cancers occurring in AIDS, may respond to chemotherapy. Some of these drugs have included vinblastine, etoposide, doxorubicin, bleomycin, and combinations of these. High doses of interferon-alpha, although not useful in treating the underlying disorder or opportunistic infections, may be moderately effective in treating Kaposi sarcoma. Radiation therapy may also be used to treat the lesions of Kaposi's sarcoma. Generally, however, treatment is not recommended for Kaposi's sarcoma unless the lesions are producing significant symptoms.
Prevention is the key to slowing the AIDS epidemic. Among the precautions against HIV transmission recommended by the Public Health Service are the following:
For additional information on HIV and the prevention of infection, the Public Health Service and the Centers for Disease Control (CDC) provide information about AIDS and referrals to local service organizations. For more information call:
To find the nearest local facility that offers confidential counseling and testing for HIV infection contact:
National AIDS Hotline (800) 342-AIDS
There are many investigational drugs and vaccines being tested for the treatment of AIDS and opportunistic infections. Clinical trials seek to discover if a particular therapy is safe and if it has long-term effectiveness. These studies are conducted by physicians and other health professionals. Carefully conducted clinical trials are the fastest and safest way to help find treatments that may work.
In the first stage (Phase I) of clinical trials, the experimental treatment is given to a small number of people in order to determine safe doses of the medications. Larger groups of patients may then receive the therapies to help measure effectiveness (Phase II). The treatments may then be used in even larger studies (Phase III) to compare the new treatment to those already in use, or to help evaluate other side effects of the medication.
Clinical trials are based on a set of rules called a protocol. A protocol describes what types of patients (i.e., early symptoms, late disease, etc.) may participate in the clinical trial. The protocol also lays out a schedule of any laboratory tests and procedures, drugs, dosages, and the length of the study.
Each person who becomes a participant in a clinical trial must agree to be treated by the rules of the protocol. Researchers typically test groups of people who have similar symptoms or are similar in other ways (i.e., laboratory findings, etc.). All people diagnosed with HIV or AIDS are not eligible for participation in a given clinical study unless they meet the requirements of the protocol.
The AIDS Clinical Trials Information Service (ACTIS) provides free information on clinical trials that evaluate experimental treatments for adults and children with HIV infection and AIDS. Callers can speak with experienced health specialists who can answer a wide variety of questions regarding the purpose of the clinical trial, geographic location, eligibility requirements, names and telephone numbers of people to contact, and more. When a person who has been diagnosed with HIV calls ACTIS, it is advisable that they have as much information as possible regarding their medical condition. The health specialist may ask questions regarding the results of specific tests. This information enables the specialist to direct the caller to the best research center for that patient. Bilingual specialists are available to talk with Spanish-speaking callers.
ACTIS is a Public Health Service collaborative project provided by the Centers for Disease Control, the Food and Drug Administration, the National Institute of Allergy and Infectious Diseases, and the National Library of Medicine. To contact ACTIS (AIDS Clinical Trials Information Service) toll free from the United States or Canada call:
(800) TRIALS-A (800) 874-2572
TTY/TTD: (access for hearing impaired people) (800) 243-7012
International calls: (301) 217-0023
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
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