Human immunodeficiency virus infection and the acquired immune deficiency syndrome: A review

We are currently witnessing a global epidemic of a group of diseases which are known as AIDS and which have in common an underlying profound impairment of the host immune system. The causative agent,human immunodeficiency virus (HIV), has been identified and testing for antibodies to this virus has demonstrated its spread into many populations around the world. HIV is now known to give rise to a wide clinical spectrum including asymptomatic infection, progressive central nervous system infection, and the fatal immune deficiency termed AIDS. The proportion of HIV-infected persons who will eventually develop AIDS cannot be known with precision at this time although it is likely to be at least 40% and could be as high as 100%. AIDS and HIV have been reported in over half of the countries in the world including the USSR and China. The global distribution follows 3 epidemiologic patterns: that of the developed countries where the virus has primarily affected homosexual/bisexual men and intravenous drug users; that of Central Africa and parts of the Caribbean where it is essentially a heterosexually transmitted disease; and that of Asia and most of Central and South America where the disease is still rare. Although HIV has been recovered from peripheral blood, semen, saliva, tears, alveolar fluid, cerebrospinal fluid, brain tissue, and cervical and vaginal secretions, there is much data to indicate that its modes of spread are limited to sexual, parenteral (i.e. contaminated needles), iatrogenic (i.e. blood and blood products, transplantation, etc.), and perinatal (i.e. mother to offspring). There is now substantial evidence to indicate that casual contact, that is the type of non-sexual personal contact that might occur in the household, school setting, or workplace, does not give rise to HIV transmission. Similarly, transmission of HIV by insect vectors, e.g. mosquitoes, has also been effectively ruled out.