Acquired immune deficiency syndrome
AIDS begins with HIV infection. People who are infected with HIV may have no symptoms for 10 years or longer, but they can still transmit the infection to others during this symptom-free period. If the infection is not detected and treated, the immune system gradually weakens and AIDS develops.
Acute HIV infection progresses over time (usually a few weeks to months) to asymptomatic HIV infection (no symptoms) and then to early symptomatic HIV infection. Later, it progresses to AIDS (advanced HIV infection with CD4 T-cell count below 200 cells/mm3 ).
Almost all people infected with HIV, if they are not treated, will develop AIDS. There is a small group of patients who develop AIDS very slowly, or never at all. These patients are called nonprogressors, and many seem to have a genetic difference that prevents the virus from significantly damaging their immune system.
The symptoms of AIDS are mainly the result of infections that do not normally develop in people with a healthy immune system. These are called opportunistic infections.
People with AIDS have had their immune system damaged by HIV and are very susceptible to these opportunistic infections. Common symptoms are:
Note: At first, infection with HIV may produce no symptoms. Some people, however, do experience flu-like symptoms with fever, rash, sore throat, and swollen lymph nodes, usually 2 - 4 weeks after contracting the virus. Some people with HIV infection stay symptom-free for years between the time when they are exposed to the virus and when they develop AIDS.
CD4 cells are a type of T cell. T cells are cells of the immune system. They are also called "helper cells."
The following is a list of AIDS-related infections and cancers that people with AIDS may get as their CD4 count decreases. In the past, having AIDS was defined as having HIV infection and getting one of these other diseases. Today, according to the Centers for Disease Control and Prevention, a person may also be diagnosed with AIDS if they are HIV-positive and have a CD4 cell count below 200 cells/mm3, even if they don't have an opportunistic infection.
AIDS may also be diagnosed if a person develops one of the opportunistic infections and cancers that occur more commonly in people with HIV infection. These infections are unusual in people with a healthy immune system.
Many other illnesses and their symptoms may develop, in addition to those listed here.
The following illnesses are common with a CD4 count below 350 cells/mm3:
Common with CD4 count below 200 cells/mm3:
Common with CD4 count below 100 cells/mm3:
Common with CD4 count below 50/mm3:
In addition to the CD4 count, a test called HIV RNA level (or viral load) may be used to monitor patients. Basic screening lab tests and regular cervical Pap smears are important to monitor in HIV infection, due to the increased risk of cervical cancer in women with a compromised immune system. Anal Pap smears to detect potential cancers may also be important in both HIV-infected men and women.
Del Rio C, Curran JW. Epidemiology and prevention of acquired immunodeficiency syndrome and human immunodeficiency virus infection. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 118.
Piot P. Human immunodeficiency virus infection and acquired immunodeficiency syndrome: A global overview. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadlelphia, Pa: Saunders Elsevier; 2007:chap 407.
Sterling TR, Chaisson RE. General clinical manifestations of human immunodeficiency virus infection (including the acute retroviral syndrome and oral, cutaneous, renal, ocular, metabolic, and cardiac diseases). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 121.
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