Objective: Little is known about variations in patterns of sexual behaviour in different countries, cultures, and subpopulations that determine the spread of HIV-1. Quantitative studies are required to improve understanding.
Methods: To assess reported patterns of sexual behaviour, we administered a standardized questionnaire to 416 men and 498 women aged 15-49 years from a rural population in northwest Tanzania.
Results: Reported levels of sexual activity were highest in men and among younger age groups. The number of sexual partners and number of sex acts per unit of time were strongly correlated: men reported 10 times as many lifetime partners than women. Frequency of sexual partner exchange plateaued earlier in women (by age 25 years) than in men (by age 35 years). For the great majority, age of first intercourse was 15 years or younger; older subjects were older at first intercourse and had fewer lifetime partners than younger subjects.
Conclusions: This age-related pattern suggests that more recent birth cohorts have behaviour patterns that increase the risk of sexually transmitted infectious agents such as HIV. Preventive education programmes should be targeted at young adults, who adopt higher risk profiles of frequent partner exchange linked with first intercourse at an early age.