Acquired immunodeficiency syndrome (aids)

In 1981 reports of Pneumocystis carinii pneumonia, cytomegalovirus pneumonia and Kaposi's sarcoma in intravenous drug abusers and homosexual males were the first indication of what would be termed the acquired immunodeficiency syndrome (AIDS). Two years later the human immunodeficiency virus type I (HIV-I) was recognized as the primary cause of this disease. In 1986 a second human immunodeficiency virus (HIV-II) was reported in Africa as another cause of AIDS. Both HIV-I and HIV-II are retroviruses, in particular lentiviruses, which are remarkable for their complex viral genomes. Spread of these retroviruses is through sexual contact, exposure to blood or blood products, and perinatal transmission. Initial reports centred on homosexual males practising unsafe sex, intravenous drug abusers and post-transfusion patients, particularly haemophiliacs. Current epidemiological trends suggest that the most common routes of transmission are now heterosexual contact and increasingly through illicit intravenous drug use. Pathogenetically HIV-I infection takes a protracted course as the virus targets CD4+ lymphocytes in the thymus and peripheral lymphoid reservoirs. Primarily HIV infection occasionally produces an acute illness 2- 4 weeks following infection. This is typically self-limiting, lasting from 1 to 2 weeks and patients may present with fever, adenopathy, pharyngitis, rash, myalgia or arthralgia. Generally, however, patients are asymptomatic and this period goes unrecognized. Clinically patients may remain asymptomatic for over 10 years before immunodeficiency reaches a level that permits opportunistic infection or neoplasm. The diagnosis of HIV infection is typically made by ELISA or Western blot tests.

Typical opportunistic infections include pneumocystis carinii pneumonia (Fig.1), disseminated fungal infection pulmonary (Fig.2), increased incidence of bacterial pneumonia and bronchiectasis. Neoplasms associated with HIV-I infection include Kaposis sarcoma (Fig.3), non Hodgkins lymphoma, papilloma virus-associated cervical neoplasia and invasive cervical carcinoma.

Recently combinations of antiretroviral agents including zidovudine and protease inhibitors have resulted in a successful diminution of circulating viral burden within infected hosts. This has permitted some patients to regain a competent immune status and the ability to ward off infections and neoplasms. With this advance has come some optimism that AIDS may at least be temporarily controlled. Nevertheless, estimates that over 20,000,000 patients are infected with HIV worldwide and the economic inability to provide these "drug cocktails" to a majority let alone all of these individuals suggest that the AIDS epidemic will be with us for many years.

PGO