Impact of the HIV epidemic on population and household structure: the dynamics and evidence to date

Background: HIV is contracted most frequently at birth and during early adulthood. The epidemic may thus impact the demographic structure and the household structure of affected populations. Methods: This paper reviews earlier evidence of such an impact, uses demographic theory to anticipate its changes over time, and reviews the most recent evidence for indications of these changes. Results: Modest increases in the male : female ratio are beginning to show within certain age groups only (approximately 15% among 25–34 year olds). Similarly sized increases in the proportion of 15–29 year olds relative to 30–54 year olds are observed in some age pyramids. These ‘youth bulges’ are expected to fade out, whereas an aging effect phases in with the fertility impact of the epidemic. In the longer run, the size of all age groups will be reduced, but relatively less so for middle-aged adults. Proportions of orphans and widows have increased in the most affected countries. Fewer remarriage probabilities for widows were observed. Resulting increases in the proportion of female-headed households should only be temporary, as female mortality is catching up with male mortality. The number of double orphans is beginning to increase, but overall, orphans continue to live predominantly with a family member, most often the grandparents if not with the surviving parent. Conclusion: To date, the epidemic's impact on the population and household structure has been limited by demographic (aging) and social (adaptive movements of kin across households) processes that contribute to diffuse the epidemic throughout the entire population and all households.