ABSTRACT
I. Introduction The syndrome of human immunodeficiency virus (HIV) is caused by one of two retroviruses of the Lentivirus genera, HIV-1, and HIV-2. HIV-1 accounts for the majority of cases globally, being easier to transmit and progressing more aggressively than HIV-2, which is found predominantly in West Africa. Following initial infection with HIV, individuals may experience a viral type illness. Then there is usually a period of clinical latency when most are unaware of their infection. As the virus replicates, it causes progressive immunosuppression, resulting in opportunistic infections, neoplasms, and other manifestations, which eventually lead to a diagnosis of acquired immunodeficiency syndrome (AIDS). The interval between infection and the development of AIDS is highly variable, but the mean duration is about 10 years in the absence of highly active antiretroviral therapy (HAART). Respiratory infections are a common manifestation of HIV infection and occur at all stages of the syndrome. They are often the first clinical manifestation of HIV infection and sometimes prompt practitioners to make the diagnosis of HIV. It was a cluster of cases of Pneumocystis jirovecci pneumonia (PCP) in young homosexual men in New York in 1981 that were among the first cases of HIV to be described.
