Friday, December 7, 2007


(Source: UNAIDS. AIDS Epidemic update: December 2007. Geneva: UNAIDS, 2007, 4-6.)

Every day, over 6800 persons become infected with HIV and over 5700 persons die from AIDS, mostly because of inadequate access to HIV prevention and treatment services. The HIV pandemic remains the most serious of infectious diseases to challenge public health. Nonetheless, the current epidemiologic assessment has encouraging elements since it suggests:
- the global prevalence of HIV infection (percentage of persons infected with HIV) is remaining at the same level, although the global number of persons living with HIV is increasing because of ongoing accumulation of new infections with longer survival times, measured over a continuously growing general population;
- there are localized reductions in prevalence in specific countries;
- a reduction in HIV-associated deaths, partly attributable to the recent scaling up of treatment; and
- a reduction in the number of annual new HIV infections globally.

Examination of global and regional trends suggests the pandemic has formed two broad patterns:
- generalized epidemics sustained in the general populations of many sub-Saharan African countries, especially in the southern part of the continent; and
- epidemics in the rest of the world that are primarily concentrated among populations most at risk, such as men who have sex with men, injecting drug users, sex workers and their sexual partners.

In 2007 the estimated number of persons living with HIV is 33.2 million [30.6–36.1 million] which is greater than ever before. But it is important to note that there are two opposing influences acting on this figure. In the first place good prevention efforts reduce new infections; and, secondly, treatment scale-up reduces deaths among people with HIV.

Global HIV prevalence has been estimated to be level since 2001. Downward trends in HIV prevalence are occurring in a number of countries, where prevention efforts are showing results. Côte d’Ivoire, Kenya and Zimbabwe have all seen declines in national prevalence. In South-East Asia, the epidemics in Cambodia, Myanmar and Thailand all show declines in HIV prevalence.

The estimated number of deaths due to AIDS in 2007 was 2.1 million [1.9–2.4 million] worldwide, of which 76% occurred in sub-Saharan Africa. Declines in the past two years are partly attributable to the scaling up of antiretroviral treatment services. AIDS remains a leading cause of mortality worldwide and the primary cause of death in sub-Saharan Africa, illustrating the tremendous, long-term challenge that lies ahead for provision of treatment services, with the hugely disproportionate impact on sub-Saharan Africa ever more clear.

HIV incidence (the number of new HIV infections in a population per year) is the key factor that prevention efforts aim to reduce, since newly infected persons increase the total number of persons living with HIV; they will progress to disease and death; and are a potential source of further transmission. Global HIV incidence likely peaked in the late 1990s and in 2007 there was an estimated 2.5 million [1.8 – 4.1 million] new infections. This reduction in HIV incidence likely reflects natural trends in the epidemic as well as the result of prevention programmes bearing fruit.

A final conclusion concerns the quality and nature of strategic information relating to the pandemic and the effects of prevention efforts. Increased investments in interventions for HIV prevention, treatment and care are showing results. It is hard to adequately define the impact of specific interventions or programmes. This will require special studies in local areas, including assessments of HIV incidence, mortality, programme effectiveness and the burden of HIV infection, disease and death in children.

As the resources committed to AIDS and other major health problems continue to increase, more emphasis is required to strengthen systems to collect and analyse data and to improve the quality of such data to strategically guide programming. Despite the challenges and limitations inherent in data collection, the resources made available to the global AIDS response have enabled good quality statistical information that is superior to many other global disease estimates.

No comments: