Fourth-Stage HIV Disease
AIDS is the fourth and final stage of HIV disease. HIV disease weakens the immune system by targeting white blood cells called lymphocytes, specifically the CD4 T-cells. AIDS is diagnosed when these fall below 200 per cubic milliliter of blood, meaning that the immune system has become severely damaged.
Treatment for HIV disease can be started before this, as long as the infection has already been detected and CD4 level testing can be done. The Department of Health and Human Services (DHHS) recommends that antiretroviral treatment be started when CD4 cells dip below 350 per cubic milliliter of blood. In countries where this CD4 testing is not available, the World Health Organization (WHO) recommends that treatment be begun during its description of clinical stage three of HIV disease (which is somewhat different than the definition of general third-stage HIV, also known as symptomatic HIV).
AIDS is a syndrome, which is a group of conditions. In the case of HIV disease, these are known as AIDS-defining illnesses, and they fall into four categories: opportunistic infections, wasting, malignancies (cancers) and neurological conditions.
Opportunistic infections are bacterial, viral, fungal and protozoan infections that do not cause disease in people with healthy immune systems or which cause much more serious disease in immunocompromised people, i.e., people whose immune systems have lost the ability to fight off infection. These include thrush, toxoplasmosis, cytomegalovirus, Pneumocystis pneumonia and herpesviruses. Some opportunistic infections respond to antiretroviral treatment for HIV-disease, while others must be targeted more specifically. To learn more about opportunistic infections, see Resources.
Wasting is a condition that causes the loss of 10% or more of body weight, according to AIDS.org. Both HIV disease and antiviral treatment for HIV disease can worsen wasting (through symptoms like nausea, loss of appetite and vomiting), but maintaining a healthy diet and exercising can help mitigate the effects of wasting.
Some cancers are linked to advanced HIV disease; these include Kaposi's sarcoma and lymphomas. Kaposi's sarcoma is a skin cancer that produces purple lesions and is caused by an opportunistic infection with HHV-8, a herpes virus. Lymphomas are cancers of lymphocytes, cells targeted by HIV.
Neurolgical conditions of AIDS include AIDS Dementia Complex (ADC). According to HIV InSite, ADC can affect cognition and motor skills as well as behavior, and a high death rate is associated with ADC.
AIDS leads to terminal conditions, which means that end-of-life care is part of the management of advanced HIV disease. According to Avert.org, care provided at the end of life includes management of pain and other symptoms while providing support to the dying and their families.