Complacency reversing gains in war against AIDS
Drug advances are culprits in ongoing battle
Antiretroviral drugs are creating complacency in some developed countries, reversing gains in the AIDS epidemic, said Roy M. Anderson, FRS, of Wellcome Trust Centre for the Epidemiology of Infectious Disease at the University of Oxford in Oxford, England.
"Complacency is the main worry in many Western countries for the coming decade, with increases in risk behavior already apparent in young gay men as reflected, for example, in the rise in the incidences of various sexually transmitted diseases such as rectal gonorrhea in San Francisco and a concomitant recent rise in the incidence of HIV," Anderson said in his address at the XIII International AIDS Conference in Durban, South Africa.
Anderson attributes the problem partly to the perception that AIDS is a treatable condition with the advent and success of combination drug therapies. He said the slow and steady increase in the incidence of HIV in heterosexuals and the explosive epidemic of AIDS in many Eastern European countries also are of major concern.
Success of public health campaigns varies
Public health authorities, therefore, face many challenges in the coming decade, said Anderson. Those include:
• the intensification of AIDS educational campaigns for the young;
• combating the spread of drug-resistant strains of the virus;
• promoting good adherence to recommended drug regimens for those infected and on combination drug therapy;
• finding the necessary resources for enhanced surveillance to detect a higher percentage of infections early on;
• stimulating more research in the development of vaccines.
Anderson said successful public health campaigns have reduced the impact and spread of HIV, but progress varies in different countries. While Sweden has made remarkable progress in limiting the spread, Spain and certain areas of the United States have achieved much less success, he said.
"Each country has a unique epidemic formed from varying contributions by infections in gay men, IV drug users, and heterosexuals," he said.
While little variability occurred in general patterns of the distribution of age-related sexual partner acquisition, much heterogeneity exists in patterns of mixing within and between major risk groups and the degree to which educational messages have penetrated certain sectors of society in different industrialized countries, said Anderson.
Many success stories — ranging from effective needle-exchange programs to frequent use of condoms to the reduction in the number of new sexual partners — have been recorded. Drug therapy also has significantly reduced the likelihood of vertical transmission of the virus.
"What typifies the most convincing cases is the quantitative study of behavior change, concomitant with the monitoring of HIV incidence and seroprevalence," Anderson said.
He said the widespread use of highly active antiretroviral therapy (HAART) during the past five years in developed countries has had a significant impact on the incidence of AIDS, a change concomitant with an increase in the pool of HIV-infected persons as combination therapy prolonged the lives of those infected. However, it also brings the associated risks of an enhanced net rate of transmission.
And while aggressive drug therapy could lower viremia to undetectable levels and bring improvements in immune status, even the combination of five drugs does not seem to eliminate the virus from the host, he said.
Cessation of therapy, therefore, typically results in rapid growth of the virus and associated diseases, Anderson said, while poor adherence to treatment has created multidrug-resistant strains that are difficult to treat.
"Tight adherence to prescribed drug regimens is key to long-term suppression of viral load. Since the net rate of viral evolution is proportional to total viral load, poor adherence early on post the initiation of combination therapy, when viral load is declining from high levels, carries the greatest risk of the evolution of resistance. Once viral load is very low, a short period of poor adherence is less serious," he explained.
"However, the general messages for those on treatment are that good adherence is vital, as is the adoption of safe sex practices at all times," he added.
The development of vaccines is seen as a long-term solution to the epidemic, but Anderson cautioned that the path to that goal will be difficult, largely due to the great genetic diversity of the virus and its propensity for rapid evolution.
"The clear need is for action now, at a scale and degree of international collaboration not seen before in the history of the fight against infectious disease," he said. "International collaboration and political leadership are key ingredients for promoting this goal."
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