Symptoms:

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:

• Chills
• Fever
• Sweats (particularly at night)
• Swollen lymph glands
• Weakness
• Weight loss

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.

Signs and tests:

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:

• Herpes simplex virus -- causes ulcers/small blisters in the mouth or genitals, happens more often and usually much more severely in an HIV-infected person than in someone without HIV infection
• Herpes zoster (shingles) -- ulcers/small blisters over a patch of skin, caused by reactivation of the varicella zoster virus, the same virus that causes chickenpox
• Kaposi's sarcoma -- cancer of the skin, lungs, and bowel due to a herpes virus (HHV-8). It can happen at any CD4 count, but is more likely to happen at lower CD4 counts, and is more common in men than in women.
• Non-Hodgkin's lymphoma -- cancer of the lymph nodes
• Oral or vaginal thrush -- yeast (typically Candida albicans) infection of the mouth or vagina
• Tuberculosis -- infection by tuberculosis bacteria mostly affects the lungs, but can also affect other organs such as the bowel, lining of the heart or lungs, brain, or lining of the central nervous system (brain and spinal cord)

Common with CD4 count below 200 cells/mm³:

• Bacillary angiomatosis -- skin sores caused by a bacteria called Bartonella, which may be caused by cat scratches
• Candida esophagitis -- painful yeast infection of the esophagus
• Pneumocystis jiroveci pneumonia, "PCP pneumonia," previously called Pneumocystis carinii pneumonia, caused by a fungus

Common with CD4 count below 100 cells/mm³:

• AIDS dementia -- worsening and slowing of mental function, caused by HIV
• Cryptococcal meningitis -- fungal infection of the lining of the brain
• Cryptosporidium diarrhea -- Extreme diarrhea caused by a parasite that affects the gastrointestinal tract
• Progressive multifocal leukoencephalopathy -- a disease of the brain caused by a virus (called the JC virus) that results in a severe decline in mental and physical functions
• Toxoplasma encephalitis -- infection of the brain by a parasite, called Toxoplasma gondii, which is often found in cat feces; causes lesions (sores) in the brain
• Wasting syndrome -- extreme weight loss and loss of appetite, caused by HIV itself

Common with CD4 count below 50/mm³:

• Cytomegalovirus infection -- a viral infection that can affect almost any organ system, especially the large bowel and the eyes
• Mycobacterium avium -- a blood infection by a bacterium related to tuberculosis

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.