AIDS and the lung

Despite the numerous bacteria, fungi, virus and protozoa present in the air we breathe, our respiratory system is equipped with such efficient defence mechanisms that lung infections are a rare event. AIDS was identified for the first time when some previously healthy subjects developed pneumonia from Pneumocystis carinii; in fact the level of immune deficit induced by HIV infection is the factor that determines the risk of developing specific lung diseases, both infective and non infective. Before the advent of combined antiretroviral therapy (cART) bacterial pneumonia, tuberculosis and pneumonia from Pneumocystis carinii (PCP) - today Pneumocystis jirovencii - were the most frequent lung infections. With the advent of cART, opportunistic lung infections now remain the heritage of those subjects who do not undergo therapy, either because they are unaware of their condition of HIV infection or because they refuse or do not tolerate such polypharmacological treatments, or because their infection is due to a virus that is polyresitant to antiretroviral drugs. In any case, the large body of knowledge now acquired is useful in the clinical management of the ever increasing number of patients with immunodepression due to onco-hematological chemotherapy or to anti-rejection therapies in organ transplantation.