Sub-Saharan Africa has just over 10% of the world's population, but is home to almost 64% of all HIV infections, with an estimated 21.6 million to 27.4 million people living with HIV-infection. In 2005, an estimated 2.3 million to 3.1 million people in the region became newly infected, and up to 2.3 millions adults and children died of AIDS-related illnesses.

Despite these grim statistics, HIV prevalence in sub-Saharan Africa appears to be leveling off. It is thought that this stabilization is due to behavior change and increased HIV-related mortality--the numbers of people becoming infected with HIV is beginning to roughly match the numbers dying of AIDS-related illnesses.

Most sub-Saharan African countries are experiencing generalized epidemics--HIV is spreading throughout the general population, rather than being confined to populations at higher risk, such as commercial sex workers and their clients, men who have sex with men, and injecting drug users. In sub-Saharan Africa, heterosexual transmission is by far the predominant mode of HIV transmission. At the beginning of the epidemic in sub-Saharan Africa, HIV-infected men vastly outnumbered HIV-infected women; today the situation in most countries is reversed. African women are being infected at an earlier age than men, and the gap in HIV prevalence between men and women continues to grow.

Southern Africa remains the most heavily affected region within sub-Saharan Africa. In a number of countries in the region, the spread of the virus into the general population has exceeded what was previously considered possible. In Botswana, Namibia, and Swaziland, exceptionally high infection levels persist, with estimated national HIV prevalence rates as high as 33.4% in Swaziland. In Botswana, weighted antenatal clinic prevalence has remained stable at extraordinarily high rates: 36% in 2001, 35% in 2002, and 37% in 2003 and 2004. Among 30-34 year old women attending antenatal clinics, prevalence rates in 2004 were almost 50%.

South Africas epidemic also shows no evidence of slowing. Between 4.9 million and 6.1 million people in the country were living with HIV in 2005. Almost 1 in 3 pregnant women at antenatal clinics were found to be HIV-infected in 2004 and trends over time show a gradual increase in HIV prevalence. Factors responsible for the rampant epidemic in South Africa include poverty and social instability that result in family disruption; mobility linked to migratory labor systems; high levels of sexually transmitted infections; the low status of women; sexual violence; and ineffective leadership during critical periods in the spread of HIV.

Angola remains an anomaly within Southern Africa, with a relatively low adult prevalence rate of 3.7%. Surveillance in this country is spotty and epidemic data is difficult to discern. The few comprehensive reports that do exist demonstrate a growing epidemic. In Luanda, the capital, prevalence rose from 0.3% in 1986 to 4.4% in 2004.

In parts of East and Central Africa, some countries show signs of declining or stabilizing HIV prevalence rates. HIV prevalence among pregnant women in the region ranges from approximately 2% in Eritrea to 7% in Kenya, Uganda, and Tanzania. Burundi and Uganda report stabilizing epidemics, and HIV prevalence among pregnant women in Kenya has been declining, especially in urban areas. At least some of this decline seems to be due to the adoption of safer sexual practices. Studies have demonstrated fewer Kenyans engaging in intercourse with more than one sexual partner, increased condom use, and delayed sexual debut among young women. Uganda also reports continued declines in HIV prevalence rates due to the successful prevention campaign that the government waged in the late 1990s and early 2000s, although the gains that these campaigns have made are beginning to slow. In Uganda, almost 1 in 3 men reported more than one sexual partner in the previous year.

West Africa is less severely affected than other regions in sub-Saharan Africa, with national adult HIV prevalence estimates lower than 2% in several countries. Côte d'Ivoire has the highest HIV prevalence in the region at 7.1%. Significant declines in HIV prevalence among pregnant women have been observed in urban areas of Burkina Faso and Togo. However, Senegal and Ghana report increasing infection levels among antenatal clinic attendees. Nigeria, with an estimated 1.7 million to 4.2 million people living with HIV infection, is home to the third-largest population of HIV-infected people in the world. Nationally, Nigeria reports a leveling of rates among pregnant women, yet rates throughout the large country vary dramatically, ranging from 2.6% in the South to 6.1% in the North and Central regions.

Source: http://hivinsite.ucsf.edu/global?page=cr09-00-00