Through unsafe sexual contact, sharing needles with intravenous drug users, and other means of transmission, infection with the human immunodeficiency virus (HIV) has become a worldwide epidemic. Individuals who have HIV face a long challenging road. The disease has a steady natural history, starting with an asymptomatic state and progressing towards acquired immune deficiency syndrome (AIDS).
Early- and Intermediate-Stage HIV Infection
HIV targets cells of the immune system called lymphocytes that specifically possess the CD4 marker. The virus replicates and destroys these CD4 lymphocytes, interrupting the body's process of cell-mediated immunity. Given this pathophysiological process, clinicians rely on the CD4 count as a measure of a patient's immune function and the degree of disease progression. Normal CD4 counts are at least 750 cells per microliter. Early-stage HIV infection is defined as the presence of HIV with a CD4 count greater than 500, whereas intermediate-stage HIV infection occurs when the CD4 count is between 200 and 500.
Initially, HIV patients may have no symptoms or have primary HIV infection. The latter is characterized by nonspecific symptoms such as fever, rash, pain, and swelling of lymph nodes (generalized lymphadenopathy) that occur within the first four weeks of contracting HIV and lasts for a few days to two weeks. Patients may later have mild to moderate depletions of red blood cells (anemia), white blood cells (leukopenia), and platelets (thrombocytopenia). Destruction of CD4 lymphocytes continues in the early and intermediate stages of HIV infection for an average of ten years.
Advanced-Stage HIV Infection
When the CD4 count drops below 200, the HIV infection has entered the advanced stage. This is when certain infections that are easily handled by an intact immune system take advantage of this immunocompromised state (opportunistic infections). Certain cancers may also appear for the same reason. When a patient has a CD4 count less than 200 and at least one opportunistic infection or cancer specifically seen in advanced-stage HIV, he or she is officially designated as having AIDS.
A variety of opportunistic infections can appear in AIDS, including but not limited to the following:
- Candidiasis, the presence of Candida yeast in the oral cavity (oral thrush) or esophagus
- Pneumonia secondary to Pneumocystis jiroveci (formerly Pneumocystis carinii)
- Herpes simplex in the esophagus (herpes esophagitis)
- Cytomegalovirus (CMV) in the retina (CMV retinitis)
- Infection with Histoplasma (histoplasmosis)
- Infection with Coccidiodes (coccidiomycosis)
- Infection with Cryptococcus (cryptococcosis)
- Infection of the brain by Toxoplasma (toxoplasmosis)
- Diarrhea secondary to Cryptosporidium (cryptosporidiosis)
- Diarrhea caused by Isospora
- Diarrhea from Mycobacterium avium complex
For cancer in AIDS patients, the most common is Kaposi's sarcoma, a tumor that can appear in the skin, oral cavity, gastrointestinal tract, or respiratory tract. AIDS also increases the likelihood of lymphoma and cervical cancer.
The Importance of HIV Prevention
Because no cure exists for HIV and AIDS, the importance of HIV prevention cannot be stressed enough. For those who are HIV positive, taking anti-retroviral therapy to slow the decrease of the CD4 count is key for optimizing survival along with treatment of opportunistic infections and other issues as they occur.
