Rising rates of HIV infection

In the third decade of the HIV pandemic the number of infected individuals continues to increase. An estimated 38 million people world-wide, including over 2 million children, are now infected with HIV, and a record 4.8 million became infected in 2003.¹ Sub-Saharan Africa is the worst affected region: a third of the world's HIV infected population is living there. Why are infections continuing to rise, and what can be done about it?

The underlying reason for this continuing increase is socioeconomic, but the increase also represents a failure of prevention. For a large epidemic to occur in a particular country, both poverty and poor social cohesion are required. The worst epidemics are therefore occurring in countries where wars, inter-community tensions, and corruption have contributed to a disintegration of the fabric of society. HIV infection is rooted in poverty, ignorance, and a lack of autonomy of women.²

The ideal prevention would be a universally available vaccine against HIV. The presentation of negative results from the first phase III HIV vaccine programmes have led to controversial calls for a “back to basic science” approach before further, large scale trials are undertaken.³ As the underlying immunological responses required to provide protective immunity to HIV are currently unknown, the current, serendipitous approach of trying a large variety of vaccines in phase III studies will continue, although hopes for an early breakthrough are not high.

An alternative approach would be the use of microbicides to prevent transmission of infection to the recipient of HIV infected semen and possibly reduce the risk to the active partner as well. The initial studies of such an approach using the microbicide nonoxynol-9 were disappointing as this chemical was found to disrupt the vaginal mucosa. A phase II/III study with nonoxynol-9 definitively proved a lack of protection on HIV 1 transmission.⁴ Several cheap chemical alternatives are now awaiting large scale studies that will address both effectiveness and ease of use.⁵

Other preventive measures include the administration of single antiretroviral agent as pre-exposure prophylaxis in risky sexual encounters, but generating resistant virus is a serious concern. For the present, most efforts at prevention are therefore linked to trying to change behaviour.

In Thailand and Uganda, dramatic falls in the incidence of new HIV infections have coincided with concerted attempts at changing behaviours, with extensive campaigns to increase awareness of HIV and popularise the use of condoms. The fall in incidence does not prove a causal link but may be a natural consequence of the changing epidemic, with an enormous burst of infections early on coinciding with a large number of people seroconverting to HIV positivity. The lower rate of infections now may be associated with the lower rate of transmissibility during the latent “period of infection.” Therefore, although the ABC message (abstinence, be faithful, use a condom) is popular with the American government, its application in other parts of the world may not have the impact required. A range of approaches are needed tailored to the drivers of the epidemic.⁶

Until recently most authorities would not countenance treatment with antiretroviral agents on a large scale in centres with the biggest epidemics and instead advocated prevention alone, despite the comparative lack of evidence of its effectiveness. This view has been changed by the reduction in the cost of antiretroviral therapy as a result of generic manufacture and political pressure applied to the pharmaceutical companies, and by the realisation that treatment is possible in resource poor settings with rudimentary laboratory facilities. The need for close monitoring of antiretroviral treatment is the subject of a large MRC trial in southern Africa (www.ctu.mrc.ac.uk/studies/dart.asp). So far adherence rates to treatments have been high and toxicities low in resource poor settings.⁷ The widespread provision of antiretroviral treatment gives a sense of hope for people who are infected and should improve their willingness to undergo an HIV test, which may reduce the risk of transmission, and to accept measures that prevent mother to child transmission.

In the face of this global catastrophe, the epidemic in the United Kingdom seems both small and parochial. Nevertheless, the latest published figures from the Health Protection Agency show a 20% increase in the prevalence of HIV in 2003 and 2004 compared with 2002,⁸,⁹ partly because of infections acquired abroad. Some of this increase may be due to the identification of previously infected individuals. However, transmission in gay and bisexual men is increasing, as some of this high risk group revert to unprotected sex. The risk of heterosexual transmission in the United Kingdom has doubled during the past five years.

Each newly diagnosed HIV patient consumes about £12 500 ($22 600; €18 200) in healthcare costs each year. The lifetime costs of care for the current 50 000 infected individuals in the United Kingdom, with a life expectancy of 20 years, is at least £12.5bn. UNAIDS recommended that to support global HIV/AIDS programmes strong political leadership, better funding, and coordination are needed. Likewise in the United Kingdom, prioritisation of sexual health with substantial investment is essential to avoid continuing deterioration in services, rising HIV transmission, and costly consequences for tax payers.