By Dr. John J. Zurlo
It has been 28 years since the first case reports of individuals with a newly recognized immunodeficiency disorder called AIDS were described. Soon thereafter, the viral cause of AIDS, the human immunodeficiency virus (HIV), was discovered. This discovery led to the development of tests that could quickly and accurately diagnose HIV infection. We then began to watch as the epidemic spread not only in the United States and other developed nations, but to a much greater extent in the developing world, particularly on the African continent where the combination of a deadly infection coupled with an often non-existent health care infrastructure resulted in untold misery and hardship.
As World AIDS Day and AIDS Awareness Month is again upon us, it is useful to take stock of our successes and challenges in addressing the AIDS epidemic.
- What can we expect from antiretroviral treatment?
- How has the epidemic changed both in the U.S. and in the rest of the world?
- Is a cure at hand?
- When can we expect to see an effective vaccine for HIV?
These all are important questions.
The advent of effective treatment for HIV infection in the mid-1990s took most people in the field by surprise. Just a few years earlier, the numbers of new AIDS cases and deaths from AIDS seemed to be rising inexorably. Yet with the new drug cocktails not only were individuals not dying, but they were gaining weight, recovering from their complications and rediscovering their sense of wellbeing. Death rates plummeted. Clearly there was a new sense of optimism including the possibility of curing HIV, with a capital “C”.
Since those early days, we have come to understand both the successes and limitations of combination antiretroviral therapy. We quickly learned that while the virus can be completely suppressed for an indefinite period of time, it still lingers in long-lived white blood cell populations. When treatment stops, the virus comes marching back. Hence a cure remains elusive. Yet treatment has become both simpler and safer. The early regimens were cumbersome and plagued with troublesome side effects. Current regimens as simple as one pill daily, while not free of side effects, have boosted the number of people living with HIV whose virus is fully controlled. Many of these individuals live completely normal lives and have the potential to live a normal life span.
Unfortunately the epidemic lives on. In the U.S. we have new data indicating that around 56,000 people were newly infected in 2006. HIV continues to affect minority populations disproportionately, especially the African-American community. New infections in gay men continue to be a problem, and concern has been raised that the hard fought gains in reducing risky behaviors among gay men have given way to more lax attitudes under the assumption that HIV can be easily treated.
Perhaps most significant is the problem of infected individuals who are undiagnosed, a group that numbers around 250,000. Not only are they spreading HIV unknowingly but they often present late in the course of their infection with advanced AIDS and die before antiretroviral therapy can take effect.
The world picture of HIV continues to be daunting, but glimmers of hope filter through. According to the World Health Organization (WHO), there were 33.4 million people living with HIV in 2008, the vast majority in sub-Saharan Africa. It’s estimated that 2.7 million new infections occurred that year. This number seems high, but it is an improvement from 1996, when new infections peaked at 3.5 million. Similarly the number of deaths in 2008 (2 million) is down from a peak of 2.2 million in 2004. These reductions have been the result in part of an increasingly coordinated effort among nations to make available and distribute antiretroviral therapies to those most in need. As of December 2008, approximately 4 million people in low-income countries most affected by HIV were receiving treatment, a tenfold rise since 2003. While we have come a long way, we clearly have an even longer way to go.
An effective, preventative HIV vaccine remains an important but elusive goal. There are two important roadblocks to successful vaccine development. One is the great genetic variability of HIV that makes it difficult to develop a one-size-fits-all effective vaccine. Even more significant is our lack of understanding of what constitutes an effective immunologic response against HIV. What seems clear is that antibodies that are stimulated by the typical vaccine are not sufficient to protect against HIV. Despite these challenges, the reports of partial success of a recently tested vaccine offer at least a ray of hope that we may be onto something important.
We have indeed come a long way since the bleak days when AIDS emerged as a modern-day plague. It is ironic that this small, deadly virus has helped unite the world community toward a common cause and could perhaps be a model for cooperation in the 21st century that transcends national boundaries. We can only hope.
Dr. John J. Zurlo is a professor of medicine in the Division of Infectious Diseases and Epidemiology at Penn State Milton S. Hershey Medical Center.