Evidence for heterosexual transmission and clinical manifestations of human immunodeficiency virus infection and related conditions in Lusaka, Zambia.

In a hospital-based survey in Lusaka, Zambia, 189 (17.5%) of 1078 subjects had antibodies against the human immunodeficiency virus (HIV). The prevalence of antibodies was low in subjects aged less than 20 or greater than 60 years; in men the peak prevalence (32.9%) occurred in those aged 30-35 years, and in women (24.4%) it occurred in the 20-25 year age-group. There was no significant difference in prevalence by sex after adjusting for age. High educational level was independently associated with HIV seropositivity; the antibody against HIV was found in 18.4% of blood donors and in 19.0% of hospital workers. Among patients the antibody prevalence ranged from 8.7% in antenatal women and 9.3% in orthopaedic patients to 29.2% in those attending sexually transmitted disease (STD) clinics (the prevalence being 37.3% in previous attenders and 22.8% in first-time attenders). Seropositivity rates were higher in patients with an infectious problem (23.4%) than in those without (11.4%, p = 0.0002). Herpes zoster, oral thrush, diarrhoea, tuberculosis, and weight loss were independently correlated with seropositivity. The data strongly suggest that HIV infection is prevalent in Africa and is transmitted heterosexually. The restricted distribution of seropositivity to the sexually active age-groups indicates that the epidemic, at least in this part of Africa, is newly introduced; this has substantial implications for prevention.