There are 56,300 new cases of HIV infection in the United States yearly according to 2010 information from the National Institute of Allergies and Infectious Diseases. HIV, or Human Immunodeficiency Virus, attacks the immune system by destroying CD4, or T-cells, a type of white blood cell that fights infection. A T-cell count of less than 200, or an opportunistic infection, signals the advancement of the HIV disease to AIDS. The advance stages of AIDS are medically complicated.
CD4 Count
According to AIDS.org, a CD4 cell is also known as a T-lymphocyte cell. T4 cells are called helper cells and they initiate the fight against infections. When a patient contracts HIV, the virus invades the T4, or CD4, cells. When the CD4 cells multiply to fight infection, they also multiply the HIV virus. Eventually the HIV overwhelms the T-cells and they are depleted. When CD4 counts becomes less than 200, a patient is considered to have AIDS. This is important because for some patients, this is an indication that they need to start HAART, or highly activated antiretroviral therapy. HAART uses combinations of three or more HIV medications to slow the replication of the virus. In advanced AIDS, a CD4 count less than 200 places the patient at risk for opportunistic infections. Opportunistic infections are infections that people with healthy immune systems don't contract. These bacterium, parasites and fungi, recognize a host with a depleted immune system and thrive in that environment.
Pneumocystis Pneumonia
In advance AIDS, many patients have depleted immune systems and need medications to prevent opportunistic infections. Patients with CD4 counts less than 200 are susceptible to pneumocystis pneumonia, or PCP. PCP is an insidious lung infection, caused by Pneumocystis jiroveci, a ubiquitous pathogen found in the soil. The initial symptoms of this pneumonia are shortness of breath, which can progress to respiratory distress if not treated. Patients are placed on sulfamethoxazole and trimethoprim (Bactrim and Septra) for prevention.
Toxoplasmosis and Cryptococcus
According to AIDS.org, patients with CD4 counts less than 100 are at risk for Toxoplasmosis and cryptococcus. Toxoplasmosis is a parasite that infects the brain. Cryptococcus is a fungus that causes infection of the membranes lining the brain. Sulfamethoxazole and trimethoprim can prevent toxoplasmosis. Cryptococcus can be treated with antifungals.
Mycobacterium Avium Complex
CD4 counts less than 75 signal very advanced AIDS and patients are at risk for Mycobacterium Avium Complex, or MAC. This bacteria can spread throughout the body and causes severe illness. Sometimes azithromycin and clindamycin, common antibiotics, are used for prevention.
