Normally, the immune system fights off infections and certain diseases that invade the body. However, HIV progressively destroys the body's ability to fight infections and certain cancers by killing or impairing cells of the immune system.
Symptoms of HIV Infection
Although many people do not exhibit any symptoms when they first become infected, some develop a flu-like illness within 1-2 months following exposure to the virus. This is characterized by fever, headache, malaise, and enlarged lymph nodes. These symptoms usually disappear within a week to a month and may be mistaken for another type of viral infection.
More severe symptoms may not surface for a month to a decade or more following HIV infection, and within two years in children born with HIV infection. This period of "asymptomatic" infection is highly variable. During this period, HIV is actively infecting and killing cells of the immune system, and is seen most obviously by the decline in the blood levels of CD4+ T cells (also known as T4 cells), which are the immune system's key infection fighters.
As the immune system deteriorates, a variety of complications arise. The first symptom experienced is normally enlarged lymph nodes for a period of more than three months. Other symptoms often experienced months to years before the onset of AIDS include a lack of energy, weight loss, frequent fevers and sweats, persistent or frequent yeast infections, persistent skin rashes or flaky skin, and pelvic inflammatory disease. Some develop frequent and severe herpes infections or a painful nerve disease known as shingles.
Onset of AIDS
In 1993, the Center for Disease Control revised its definition of AIDS to include all HIV-infected people with a CD4+ T cell count of less than 200. (Healthy adults usually have CD4+ T-cell counts of 1,000 or more.) In addition, the definition includes 26 clinical conditions that affect people with advanced HIV disease. Most AIDS defining conditions are opportunistic infections , which are caused by microbes that usually do not cause illness in healthy individuals. In people with AIDS, however, these infections are often severe and sometimes fatal because the immune system is so ravaged by HIV that the body cannot fight off certain bacteria, viruses, and other microbes.
Opportunistic Infections
Opportunistic infections common in AIDS patients cause symptoms such as coughing, shortness of breath, dementia, seizures, severe and persistent diarrhea, fever, vision loss, severe headaches, wasting, extreme fatigue, nausea, vomiting, lack of coordination, coma, abdominal cramps, or difficult or painful swallowing. Children are susceptible to the same opportunistic infections as adults, and also experience severe forms of bacterial infections normally occurring during childhood, including conjunctivitis (pink eye), ear infections, and tonsilitis.
People with AIDS are particularly prone to developing various cancers and lymphomas (cancers of the immune system). The most common malignancies associated with HIV disease are Kaposi's sarcoma (KS) and non-Hodgkin's lymphoma (NHL). The most common infection is Pneumocystis carinii pneumonia (PCP) . Neurological manifestations, including peripheral neuropathy and AIDS dementia complex also occasionally appear. Other opportunistic infections associated with AIDS are listed here.
Additional Sites:
The AIDS Education Global Information System (AEGIS)
The Center for Disease Control National AIDS Clearinghouse
Project Related Links
Main Page -- AIDS Overview
AIDS and the Immune System
Current and Future Treatments
The Life Cycle of AIDS
