a viral disease caused by Lentivirus of two serotypes, HIV-1 and HIV-2. For a general description, see human immunodeficiency virus HIV virus infection.

HIV infection frequently leads to the acquired immunodeficiency syndrome AIDS . HIV infection compromises the body's defence mechanisms which, in turn, predisposes infected persons to various opportunistic infections, anaemia, arthritis, myositis and immune-related neoplasms. Frequently the musculoskeletal system is affected.

Rheumatologic manifestations of HIV infection include forms of spondyloarthropathy, arthritis and enthesitis. Infectious disorders that complicate HIV infection include osteomyelitis, septic arthritis, pyomyositis and septic bursitis. The knee, joints of the upper extremity, and the acromioclavicular, sternoclavicular and sacroiliac joints may be affected. Bacillary angiomatosis has been observed in patients infected with the HIV virus, who typically have multiple friable angiomatous papules closely resembling pyogenic granulomas as well as the skin lesions of Kaposi's sarcoma. Fever, chills, weight loss, night sweats, cellulitis and subcutaneous nodules are additional clinical manifestations. Bone lesions (predominantly osteolysis) sometimes represent the initial manifestation of the disease.