Some 60 000 fewer people died of AIDS last year than in 2005, thanks mainly to the country's antiretroviral treatment campaign.

This is according to the Actuarial Society of Southern Africa (ASSA), which has been tracking and modelling the HIV/AIDS epidemic for over 25 years.

According to the new ASSA model, "the annual number of AIDS deaths in South Africa has reduced from 257 000 in 2005 to 194 000 in 2010", largely because of the "rapid expansion of the South African antiretroviral treatment programme".

The new model, ASSA2008, estimates that last year 10.9% of the South African population was infected with HIV, with 5.5 million people living with HIV.

Based on "substantial increases in condom use over the last decade, which is supported by findings from recent household surveys", ASSA2008 estimates that HIV prevalence in young people aged 15 to 24 has dropped from 9.2% in 2005 to 7.7% in 2010.

However, the society estimates that HIV prevalence in South Africans aged 15 to 49 has increased slightly from 16.4% in 2005 to 17% in 2010, partly because "HIV-infected adults surviving for longer due to antiretroviral treatment".

KwaZulu-Natal, the province worst affected by HIV, had triple the HIV prevalence rate of the least affected province, the Western Cape (almost 15%). Life expectancy in KwaZulu-Natal was 10 years lower than the Western Cape, at 53.4.

Professor Rob Dorrington, the main author of ASSA2008 and Director of the Centre for Actuarial Research at the University of Cape Town, warned that it was difficult to estimate future AIDS mortality as there is " much uncertainty regarding long-term survival rates after antiretroviral treatment initiation".

The ASSA2008 model also does not take into account recently introduced HIV prevention strategies, the most significant of these being the promotion of male circumcision. This has been shown to reduce rates of heterosexual HIV transmission by around 60% among men.