Incidence and risk factors for HIV-1 infection—a summary of what is known and the psychiatric relevance

Abstract

The human immunodeficiency virus type 1 (HIV-1) epidemic continues to grow both within the United States and worldwide. Currently, HIV-1 disease is the greatest killer of American men and third greatest killer of women aged 25–44. The major routes of HIV-1 transmission are: (i) heterosexual and (ii) homosexual sex with infected partners; (iii) injection drug use (IDU) with a needle previously used by an infected person; and (iv) transmission from an infected mother to her infant. The HIV-1 epidemic in industrial countries initially occurred largely among homosexual men, but now 53% of American AIDS cases occur in IDUs and heterosexual/infant risk groups. While the risk of infection from a single unsafe sex or IDU act may be less than one per cent, the repeated practice of these activities by participants makes overall risk quite great. Cessation of risky drug use and/or sexual behavior is the only way to prevent transmission by these routes. Use of condoms in sex, while not 100% effective, dramatically reduces risk of sexual HIV-1 transmission, while exclusive use of clean needles (i.e., from a needle exchange program) eliminates risk for IDUs. Risk of transmission from an infected mother to infant is 20%-30% in developed countries, but can be reduced greatly by zidovudine therapy and avoidance of breast feeding. HIV-1 is not transmitted by casual contact.