The Centers for Disease Control and Prevention, or CDC, notes that at the end of 2006, an estimated 1,106,400 persons in the United States were living with HIV infection, with 21 percent undiagnosed. Without treatment, HIV progresses quickly to AIDS. A collection of opportunistic infections and low CD4 counts, defines end-stage AIDs.
Low CD4 Counts
CD4 counts, sometimes called T-cell counts, represent the number of a particular type of white blood cell present in the body. HIV infects the T-cell line of white blood cells. T-cells, or T4-lymphocytes, are cells that fight off infection. Without these cells, opportunistic infections, OIs, occur. Opportunistic infections are a type of infection that people with normal immune systems don't contract. The pathogens that cause OIs, recognize a poorly functioning immune system and take the "opportunity" to invade the host. One of the definitions of AIDS is a T-cell count, or CD4 count, of less than 200. Many healthcare providers begin anti-retroviral medications when the T-cell count is less than 350, according to AIDS.org.
Cytomegalovirus
Cytomegalovirus, CMV, is a virus that is common in 50 to 85 percent of the American population, according to AIDS.org. An intact immune system prevents this virus from becoming a problem. People with end-stage AIDS and CD4 counts less than 50 are subject to symptoms of CMV. Cytomegalovirus usually invades the retina of the eyes and causes blindness. The first signs of CMV retinitis are floaters, flashes of light, distorted and/or decreased visual acuity. AIDS.org notes that people with active CMV infection transmit the HIV virus easier. There is controversy surrounding the use of ganciclovir for prevention.
Toxoplasmosis
Toxoplasmosis is a single-cell parasite caused by Toxoplasma gondii. A parasite survives by living off of the nutrients of the host it infects. Toxoplasma gondii live in the soil and can be found in cat feces, raw vegetables and raw meat, especially pork, deer or lamb. Fifty percent of the population is infected with toxoplasmosis. T-cell counts of less than 100 provide the opportunity for infection. Encephalitis, or infection of the brain, is the end result. Symptoms include headache, tremors, seizures, personality changes and fever. Left untreated, coma and death result. Prevention with sulfamethoxazole-trimethoprim is recommended for people with T-cell counts less than 200.
