Latest statistics call into question the World Health Organisation strategy, writes DR WILLIAM REVILLE
IT IS NOW 27 years since Aids first attracted attention on the international scene. Intensive campaigns to educate the public on ways to avoid contracting Aids, and programmes of scientific research to find a cure or treatments for Aids, have been running since the disease first appeared. Originally noticed in the male homosexual community of San Francisco, warnings were issued for years of the risk of a global Aids epidemic spreading among heterosexuals.
The latest statistics on Aids, Aids Epidemic Update, were published in December 2007, by the Joint United Nations Programme on HIV/ Aids through the World Health Organisation (Who). It is now admitted by Kevin de Cock, head of Who's HIV/Aids department, that the threat of a global heterosexual pandemic has disappeared. It seems the universal prevention strategy promoted by the major Aids programmes was misdirected.
Aids is caused by the HIV virus. The Who statistics report that 33.2 million people worldwide were infected with HIV in 2007, of whom 2.5 million were under 15 years old. About 2.5 million people (including 420,000 children) were newly infected with HIV in 2007, and 2.1 million people died from Aids in 2007, including 330,000 children. More than 6,800 people become infected with HIV every day and more than 5,700 people die from Aids. Globally, the HIV pandemic is the most serious infectious disease challenge to public health.
The global pattern of HIV infection shows two clear parts. A) Aids is the leading cause of death in Sub-Saharan Africa with epidemics in the general populations, especially in the southern parts, and 76 per cent of global Aids deaths in 2007 occurred here. B) Aids epidemics in the rest of the world are primarily concentrated in certain high risk groups - men who have sex with men (MSM), injecting drug users (IDU), and sex workers and their clients.
The following statistics report the numbers in millions with HIV in 2007 (first figure in brackets) and the per cent adult prevalence of HIV (second figure in brackets): Sub-Saharan Africa (22.5, 5); Middle East and North Africa (0.38, 0.3); South and SE Asia (4, 0.3); East Asia (0.8, 0.1); Oceania (0.075, 0.4); Latin America (1.6, 0.5); Caribbean (0.23, 1.0); East Europe and Central Asia (1.6, 0.9); Western and Central Europe (0.76, 0.3); North America (1.3, 0.6).
Global HIV incidence probably peaked in the late 1990s and is now in a slow decline. Sub-Saharan Africa remains most affected. This region's epidemics vary significantly in scale, with national adult HIV prevalence ranging from less than 2 per cent in some countries to more than 15 per cent in most of South Africa.
Why is the situation so bad in Sub-Saharan Africa? Many factors operate here and interact to exacerbate the situation. These include high numbers of commercial sex workers, concurrent sexual partnerships, high rates of genital herpes which cause ulcers on the genitals through which the virus can enter the body, and low rates of male circumcision, which is protective against Aids.
Outside of Sub-Saharan Africa, Aids tends to concentrate in the high-risk groups already itemised. The Centres for Disease Control in America estimated the most likely route of infection with HIV for men living with Aids in the US in 2006 was MSM (59 per cent), IDU (20 per cent), heterosexual contact (11 per cent), MSM+IDU (8 per cent), unknown (1 per cent). For women the figures were heterosexual contact (65 per cent), IDU (33 per cent), unknown (3 per cent).
By the end of 2006, Ireland had reported a cumulative total of 4,419 HIV cases. Of these, 909 had developed Aids and 397 had died. About 40 per cent of HIV cases had been infected through heterosexual contact, 32 per cent through IDU and 23 per cent through MSM. The relatively high proportion infected through heterosexual contact in Ireland seems to be explained by immigration from countries with generalised HIV epidemics. In 2006, Ireland reported 337 new HIV infections and three deaths from Aids, the lowest reported number of deaths since 1985.
It now seems the global Aids effort has spent far too much money educating people about Aids who are not at risk. A far bigger impact could be achieved by concentrating on high-risk groups and interventions known to work such as limiting the number of sexual partners and male circumcision (which cuts risk of infection by 60 per cent).
One problem area in the Aids strategy is men who have sex with men. De Cock, quoted in the Independent, says: "We face a bit of a crisis [in this area]. In the industrialised world, transmission of HIV among men who have sex with men is not declining and in some places it has increased. It is astonishing how badly we have done with men who have sex with men. It is something that is going to have to be discussed much more rigorously."
• William Reville is associate professor of biochemistry and public awareness of science officer at UCC http://understandingscience.ucc.ie