Q and A: Does AIDS have a significant impact on population growth?

The high degree of HIV prevalence worldwide has had an impact on population growth rates. In the early 1990s, few experts predicted the current level of HIV/AIDS cases. In fact, many believed that AIDS would have little or no impact on population growth. At that time, it was difficult to predict or imagine that there would be any country with 25 percent of the population between the ages of 15 to 49 living with HIV.

Since the bubonic plague of the 14th century, no epidemic has had as strong an influence on population growth as HIV/AIDS. The plague, or Black Death, killed an estimated 25 million to 35 million people in Europe alone, a number that represented approximately one-third of its population. According to recent estimates by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO), 33.2 million people were living with HIV in 2007.

Percent of World's HIV/AIDS Cases, 2005

Note: Numbers are rounded.
Source: United Nations Population Division, Population and HIV/AIDS 2007 Wallchart.

In some regions, the impact of AIDS has been more pronounced. Africa accounts for 71 percent of the global HIV/AIDS cases, despite the fact that only 14 percent of the world's population lives there. In nine countries in Africa, at least one out of every 10 adults is HIV positive. Asia makes up the next largest proportion of all HIV/AIDS cases at 14 percent.

For some countries, the AIDS epidemic has nearly erased improvements in life expectancy achieved in the last 20 years. In southern Africa, one of the worst affected regions, life expectancy has declined from 61 to 49 years over the last two decades. The most direct impact has been the increase in the overall number of deaths. Mortality patterns of adults are much higher than they would have been if AIDS were not so prevalent. Additionally, infant and child mortality rates in some countries are higher than they would have been in the absence of AIDS.

As AIDS reshapes the distribution of deaths by age, it is affecting the population composition of many places. Between 1985 and 1990, deaths in eastern Africa were concentrated among young children and older adults, while adults ages 20 to 49 accounted for a smaller share of deaths: 16 percent. However, by the year 2010, it is expected that deaths among adults ages 20 to 49 will double, accounting for almost 30 percent of AIDS deaths. Deaths of large numbers of women in their reproductive years and the lower survival prospects of infected children will also reduce the size of the younger population. The new age and sex structure for some populations will result in lower growth rates. Still, the overall population size of affected countries is projected to increase due to relatively high fertility levels. Additionally, deaths from HIV have seen a decline in recent years due to the scale-up of antiretroviral treatment. The greatest impact of the epidemic on population growth is that the rate of growth is now slower.


Age-sex structure: The composition of a population as determined by the number or proportion of males and females in each age category. The age-sex structure of a population is the cumulative result of past trends in fertility, mortality, and migration. Information on age-sex composition is essential for the description and analysis of many types of demographic data.

Birth rate (or crude birth rate): The annual number of births per 1,000 total population.

Growth rate: The number of persons added to (or subtracted from) a population in a year due to natural increase and net migration; expressed as a percentage of the population at the beginning of the time period.

HIV/AIDS prevalence: The estimated percent of adults ages 15 to 49 living with HIV/AIDS.

Life expectancy: The average number of years a newborn infant can expect to live under current mortality levels. Most commonly cited as life expectancy at birth.

Mortality: Deaths as a component of population change.