AIDS is the terminal stage of disease caused by HIV. Those with AIDS have severely damaged immune systems, making it more difficult for them to fight off disease. As a result, patients are more vulnerable to developing life-threatening complications due to acquired infections, cancers and the human immunodeficiency virus's progressive effects on the brain.
Opportunistic Infections
People with AIDS are susceptible to opportunistic infections by a number of viruses, bacteria and parasites as a result of their weakened immune systems. For example, individuals with AIDS are at increased risk of herpes infections caused by the cytomegalovirus. According to MayoClinic.com, once a patient is infected with the virus, his immune system may be unable to suppress it, leading to repeated outbreaks that can cause damage to vital organs such as the lungs or intestines. People with AIDS are also vulnerable to parasitic infections such as Cryptosporidiosis and Salmonellosis---two parasites often contracted by eating contaminated foods. These infections can lead to severe diarrhea, abdominal pain, fever, chills and/or vomiting.
Candidiasis, or thrush, is a particularly common opportunistic infection caused by an overgrowth of fungus or yeast. The condition can cause white patches to form on the tongue, cheeks, throat or genitals. In poorer nations, tuberculosis---a contagious bacterial disease commonly affecting the lungs---is the leading cause of death among those with AIDS, according to MayoClinic.com.
Still other viruses that those with healthy immune systems can successfully fight off may attack the brain and cause damage to the central nervous system among those with AIDS. According to The Dana Foundation, one of the most common infections of the nervous system among those who are immunocompromised is progressive multifocal leukoencephalopathy, a virus that destroys the cells that produce myelin, which is an insulating material surrounding neurons that is necessary for transmission of nerve impulses from the brain to the body. Another opportunistic infection called cerebral toxoplasmosis---an infectious disease caused by a parasite---causes the formation of abscesses on the brain. Treatable with antibiotics, this complication is less common among AIDS patients receiving sulfa drugs or other antiretroviral treatment.
AIDS Dementia Complex
According to The Dana Foundation, the human immunodeficiency virus infects special immune cells called macrophages, triggering the release of chemicals that in excessive amounts are toxic to the brain. This toxicity can cause a serious neurological complication known as AIDS dementia complex, a condition characterized by significant deterioration of cognitive and motor skills. Patients may develop worsening concentration, attention, memory and reasoning ability. They may also have difficulty walking and balancing, moving their limbs at an abnormally slow pace.
Wasting Syndrome
Even with aggressive antiretroviral treatment, some people with AIDS may develop chronic and persistent fever, malaise, diarrhea and muscular weakness. According to MayoClinic.com, these symptoms are often associated with the onset of wasting syndrome, a condition characterized by a loss of more than 10 percent of body mass.
Kaposi's Sarcoma
AIDS-related Kaposi's sarcoma is a type of cancer that can develop among those whose immune systems are severely compromised. MayoClinic.com describes Kaposi's sarcoma as a cancer affecting the walls of blood vessels, causing darkly pigmented lesions on the skin. Kaposi's sarcoma can sometimes be prevented with highly active antiretroviral therapy, or HAART; however, fast-growing forms of the disease are known to develop even among those receiving HAART, according to the American Cancer Society. Kaposi's sarcoma is an "AIDS-defining" condition that officially marks an individual's transition from being HIV positive to having full-blown AIDS.
