AIDS is a syndrome that is caused by HIV, or human immunodeficiency virus. Worldwide, the Mayo Clinic estimates that approximately 39.5 million people are infected with HIV. HIV attacks the immune system, weakening your body's defense against infections, bacteria, viruses, some cancers, and other illnesses that might have otherwise been destroyed by a healthy immune system. The term AIDS, or acquired immunodeficiency syndrome, is used in the later stages of HIV, according to the Mayo Clinic.
Pneumocystis Pneumonia
According to Aids.org, pneumocystis pneumonia (PCP) is the No. 1 infection that kills individuals with AIDS. In non-HIV infected individuals, the immune system can fight off this infection, which is caused by a fungus. In individuals with HIV or AIDS, and some individuals whose immune systems are weakened by other diseases or medications, this fungus causes pneumonia. People who have had PCP are likely to become reinfected with it because they have become weaker and have lost weight from the previous bout with the infection.
Dementia and Nervous System Problems
Approximately 20 percent of people who have AIDS have a mild form of brain damage called neuroAIDS. This condition causes slow physical and mental functioning. A more severe form is AIDS dementia, which involves persistent problems with thinking and memory, and difficulty controlling arm and leg movements. Anti-retroviral medications have reduced the number of individuals suffering from AIDS dementia, but mild cases are often seen as patients live longer. Other central nervous system problems can include depression, memory problems, sleep disturbances and balance and walking difficulties. Peripheral neuropathy is also a type of nerve problem that affects the feet, legs and hands. It can cause burning, tingling, numbness and temperature sensitivity. Many of these problems do not arise until the later stages of AIDS.
Kaposi's Sarcoma
Kaposi's sarcoma, or KS, is a disease that is similar to cancer, but is commonly caused by HIV infection. Symptoms include red, purple or brownish lesions, typically on the face, arms and legs. Other places KS can occur are the linings of the mouth or nose, lungs, liver, intestines and lymph nodes. It is estimated that about 20 percent of individuals with AIDS who are not on any AIDS medications will have KS. As the disease progresses, lesions on the feet and legs can make walking difficult, lesions in the intestines can cause internal bleeding or blockages, and lesions on the lungs can cause fluid to build in the lungs, which can be fatal.
Opportunistic Infections
A healthy immune system can typically fight off many of the bacteria and viruses commonly encountered in everyday life; an immune system weakened by AIDS cannot. Infections and diseases use this weakened immune system to enter the body, and are called opportunistic infections, or OIs. Common OIs include candidiasis, or thrush, which is a fungus that infects the vagina, mouth or throat; herpes viruses, causing frequent oral or genital herpes outbreaks; toxoplasmosis, an infection of the brain; and tuberculosis, a bacterial lung infection that can also cause meningitis.
