Human immunodeficiency virus is a retrovirus that specifically attacks CD4+ T cells and progressively destroys the immune system. HIV is a latent virus, meaning that the virus causes the immune system to lose its function over time, thereby leaving the individual susceptible to numerous forms of cancer and foreign, infectious pathogens. As the individual's immune system is progressively depleted of T cells, AIDS develops--a grouping of about 26 diseases that are believed to be caused by the weakening of the immune system. HIV and AIDS negatively affect the immune system, the gastrointestinal tracts and respiratory system.
Immune System
HIV specifically targets, infects and depletes CD4+ T cells responsible for cell-mediated immunity. CD4+ cells interact with helper T cells to activate both B cells, which produce antibodies, and cytotoxic T cells, which engulf and destroy immune cells that are infected with the HIV virus. Without helper T cells, the body is unable to mount an appropriate immune response, including the production of antibodies and the elimination of infected T cells by cytotoxic T cells. The depletion of the body's immune system leaves the individual highly susceptible to different kinds of infections including histoplasmosis, toxoplasmosis, herpes virus, tuberculosis and many more. Although these infections do not cause disease in healthy individuals, these infections become life-threatening in AIDS patients due to the depletion of the immune system.
Gastrointestinal System
Gastrointestinal diseases associated with HIV/AIDS include diarrhea, nausea, vomiting, wasting syndrome and anorectal disease. According to hivinsite.ucsf.edu, diarrhea is the most common gastrointestinal manifestation of HIV disease, with a prevalence range of 0.9 percent to 14 percent. This prevalence is increased in homosexual people and individuals with advanced HIV disease. Pathogens such as Mycobacterium avium-complex and Cryptosporidium are the primary agents of chronic diarrhea in immunocompromised patients. Another common gastrointestinal disease associated with AIDS is wasting syndrome. Wasting syndrome accounted for 20 percent of AIDS diagnoses in 1995 and is defined as an involuntary weight loss of greater than 10 percent of the baseline body weight accompanied with chronic diarrhea, weakness and fever in the absence of an infection.
Respiratory System
Due to the large number of CD4+ T cells and other immune cells, the lungs are a major targeted organ for HIV infection As the HIV virus progressively destroy the immune cells in the lung, the HIV- positive individual becomes highly susceptible to developing opportunistic lung diseases including bacterial pneumonia, pneumocysist jiroveci pneumonia and tuberculosis. According to Info.gov.hk, there is a direct association between immunosuppression in HIV-positive individuals and an increased risk of developing pulmonary infections. Upper respiratory tract infection, acute bronchitis and acute sinusitis are the most frequently diagnosed respiratory diseases in HIV-positive individuals.
